Two last minute papers for 2009 from Palaeodiversity. This is an open access journal so these papers and others can be downloaded for free from here.
Maisch, M.V., Vega, C.S., and R.R. Schoch. 2009. No dicynodont in the Keuper – a reconsideration of the occurrence of aff. Dinodontosaurus in the Middle Triassic of Southern Germany. Palaeodiversity 2:271-278.
Abstract - An isolated humerus, attributed to a dicynodont therapsid and identified as aff. Dinodontosaurus, from the Lower Keuper (Middle Ladinian, Middle Triassic) of southwestern Germany is redescribed. An additional but smaller humerus that is similar in morphology might pertain to the same taxon. Several morphological features preclude an identification of the material as either aff. Dinodontosaurus, a dicynodont, or even a synapsid. The deltopectoral crest shows a number of tubercles, probably for muscle attachment. The supinator process is strongly developed and clearly offset from the rest of the bone. The distal articulation facet is very narrow transversely. There is no foramen entepicondyloideum. The ectepicondyle has a deeply concave distal surface, at least in the large and presumably adult specimen. An alternative identification for the two humeri proves difficult, as they do not agree with any other known tetrapod from the Lower Keuper. They bear close resemblance, however, to the humerus of the Permian temnospondyl Eryops, suggesting the presence of an as yet unknown temnospondyl.
This paper also emphasizes the importance of correctly determining taxonomic identity when using incomplete or unique specimens for biostratigraphic correlations.
Spielmann, J.A., Lucas, S.G., Heckert, A.B., Rinehart, L.F., and H. R. Richards III. 2009. Redescription of Spinosuchus caseanus (Archosauromorpha: Trilophosauridae) from the Upper Triassic of North America. Palaeodiversity 2: 283–313.
Abstract - Our reexamination of the holotype of Spinosuchus caseanus from the Upper Triassic of West Texas, in addition to the recognition of additional records of this taxon, demonstrates that it is closely related to the trilophosaurid archosauromorph Trilophosaurus and thus is included in a revised Trilophosauridae. Previous arguments suggesting that features that unite Spinosuchus and Trilophosaurus are not limited to these two taxa or are symplesiomorphies shared with a wide variety of contemporaneous Triassic archosauromorphs are not substantiated based on a detailed comparative analysis of the two taxa. The distinctive neural spine morphology of Spinosuchus allows for recognition of this taxon based on isolated vertebrae and thus increases its biostratigraphic value. Spinosuchus is restricted to strata of Adamanian age and is therefore an index taxon of the Adamanian land-vertebrate faunachron.
One interesting aspect of the new referred specimens of Spinosuchus is that they co-occur in a quarry in which the only other recovered material (cranial and postcranial) has been referred to Trilophosaurus jacobsi (Spielmann et al., 2007). Dorsal and sacral vertebrae from the quarry represent Spinosuchus, whereas all of the other material (that does not include dorsal and sacral vertebrae) where referred to T. jacobsi (i.e. there is no duplication of elements). Thus, although discounted by Spielmann et al. (2009) is seems possible that all of the material may indeed belong to a single taxon and that T. jacobsi would be a junior synonym of S. caseanus. Spielmann et al. (2009) claim that dorsal vertebrae from the quarry exist that are more similar to Trilophosaurus buettneri and not Spinosuchus, thus the taxa are not the same, but this will have to await future description of this material.
It also seems strange (and unstable) to diagnose Trilophosauridae based solely on shared vertebral laminae and not including characters of the unique skull and tooth morphology that has historically diagnosed the taxon, but again this determination will rely on future material being recovered.
Tawa hallae makes USA Today's List of "Biggest Discoveries in Science" for 2009
http://www.usatoday.com/tech/science/2009-12-29-science2009review29_ST_N.htm?loc=interstitialskip
Good to see paleontology and the anniversary of Charles Darwin's birth figured prominently.
Good to see paleontology and the anniversary of Charles Darwin's birth figured prominently.
End of the Year Happenings
I have not posted for a bit, things have been quite slow in the Triassic recently and I've been busy with the holidays. I also just joined Facebook and am trying to figure out what it is all about, however, most of my recent effort has been going towards finishing up (and starting) a group of manuscripts that are either due or that I have been wanting to get to for a long time.
I'm working on a few year end posts, which I hope to have out soon, but in the meantime I've been engrossed in Scott Sampson's recent book "Dinosaur Odyssey" (a Christmas present). I don't normally read too many general dinosaur books, usually preferring paleontologist biographies, books on historic field work, or civil war histories, but Scott's book is highly interesting and informative and I'm having a hard time putting it down. I'm only a third of the way through, but would already highly recommend it as a good current read on dinosaur paleontology. I'm also deeply honored that Scott mentions our recent Triassic work, especially on early dinosaurs.
I'm working on a few year end posts, which I hope to have out soon, but in the meantime I've been engrossed in Scott Sampson's recent book "Dinosaur Odyssey" (a Christmas present). I don't normally read too many general dinosaur books, usually preferring paleontologist biographies, books on historic field work, or civil war histories, but Scott's book is highly interesting and informative and I'm having a hard time putting it down. I'm only a third of the way through, but would already highly recommend it as a good current read on dinosaur paleontology. I'm also deeply honored that Scott mentions our recent Triassic work, especially on early dinosaurs.
Another Mystery Fossil from the Chinle
The identification of these two specimens has been bugging me for a few years now. These are the only two specimens like this that I have ever seen and they were collected from pretty much the same locality and horizon (Sonsela Member, Chinle Formation) in the Petrified Forest. They are thick bones, characterized by their triangular shape (one is missing a corner) and by a short but deep notch in what presumably is the dorsal end. It is bilaterally symmetrical, thus represents a mid-line element, and the lateral edges show possible open sutures. The photos show the tops and updersides of the two elements.
I have a working hypothesis on what I think they are (at least what bone) but I'd like to hear your opinions.
I have a working hypothesis on what I think they are (at least what bone) but I'd like to hear your opinions.I Swear I Didn't Say That! Having someone else put your foot in your mouth for you
One of the scariest things I've found about being contacted by the media regarding your scientific expertise on a particular subject is reading or hearing the end results. Quite often due to either a lack of comprehension on the part of the interviewer or some final editing what appears is not quite what you meant (or in some cases the complete opposite). It is not so easy to shrug this off in the days of "You Tube" and file sharing as this is now a permanent (and often heavily distributed) record of you saying something that you did not, especially if you do not agree with what "you said" at all. Possibly this could be embarrassing for you as well depending on how your "thoughts" are perceived by your colleagues.
Matt Wedel was the recent recipient of this type of "quote mining" as Darren Naish put it (including having his name mispelled through the entire show). He is quite angry about it and has commented here and here. Several fellow bloggers and colleagues have chimed in as well including Darren Naish and David Hone.
I discussed something similar on this blog a little over a year ago. In my situation I submitted proof corrections that were either not made or incorrectly made. Again this is a situation where something permanent is going on the record with my name on it containing errors that are distorting the information that I wished to provide.
Who 'proofs' the proofs, and who has the final say on scripted interviews? Because our names (and hence reputations) are on the line here, I think that it should be us, the scientists. I think that it is simply common courtesy to check back during final production and make sure that we are being accurately represented, as often we are providing this information also as a courtesy. Maybe it is simply best just not to answer the phone, but really that is against all we stand for as scientists. Science is meant to be shared and discussed and tested; however, it's often pretty rough to have to defend yourself for something someone else actually said.
By the way this also happens in exhibits and interpretive media for museums, National Parks, etc... As the specialist you really have to make sure you are involved in every step of production or you probably are not going to be happy with the end result. The question now is, what collectively as a group we can do about this to make sure it doesn't keep happening (there is actually some detailed discussion of such options going on right now on the various vertebrate paleontology list servers)? How do you get yourself involved in on the final production when simple common courtesy isn't happening?
Matt Wedel was the recent recipient of this type of "quote mining" as Darren Naish put it (including having his name mispelled through the entire show). He is quite angry about it and has commented here and here. Several fellow bloggers and colleagues have chimed in as well including Darren Naish and David Hone.
I discussed something similar on this blog a little over a year ago. In my situation I submitted proof corrections that were either not made or incorrectly made. Again this is a situation where something permanent is going on the record with my name on it containing errors that are distorting the information that I wished to provide.
Who 'proofs' the proofs, and who has the final say on scripted interviews? Because our names (and hence reputations) are on the line here, I think that it should be us, the scientists. I think that it is simply common courtesy to check back during final production and make sure that we are being accurately represented, as often we are providing this information also as a courtesy. Maybe it is simply best just not to answer the phone, but really that is against all we stand for as scientists. Science is meant to be shared and discussed and tested; however, it's often pretty rough to have to defend yourself for something someone else actually said.
By the way this also happens in exhibits and interpretive media for museums, National Parks, etc... As the specialist you really have to make sure you are involved in every step of production or you probably are not going to be happy with the end result. The question now is, what collectively as a group we can do about this to make sure it doesn't keep happening (there is actually some detailed discussion of such options going on right now on the various vertebrate paleontology list servers)? How do you get yourself involved in on the final production when simple common courtesy isn't happening?
Triassic Bonanza in the New Issue of the Journal of Vertebrate Paleontology
Quite a few new Triassic papers in the December issue of JVP and one Early Jurassic paper.
Middle Triassic -
Butler, R. J., Barrett, P. M., Abel, R. L., and D. J. Gower. 2009. A possible ctenosauriscid archosaur from the Middle Triassic Manda beds of Tanzania. Journal of Vertebrate Paleontology 29:1022–1031. doi: 10.1671/039.029.0404
ABSTRACT—The Lifua Member of the Manda Beds of Tanzania (Middle Triassic: ?latest Anisian) has yielded an exceptionally important assemblage of early archosaurs, including numerous well-preserved specimens. However, the majority of this material has not been described formally, frustrating attempts to incorporate it into studies on early archosaur diversity and evolution. We describe an anterior dorsal vertebra from the Lifua Member as the holotype of a new taxon, Hypselorhachis mirabilis. Hypselorhachis is characterised by the possession of an elongate neural spine that is at least 5.5 times the height of the centrum, and can be diagnosed on the basis of a single autapomorphy relating to the morphology of the prezygapophysis. Hypselorhachis is similar to other early Middle Triassic archosaurs with elongate neural spines, including Arizonasaurus, Ctenosauriscus, and Lotosaurus. It is possible that these taxa form a clade, Ctenosauriscidae, but further anatomical and phylogenetic work is required before this can be confirmed.
-After more than 50 years of being a nomen nudum and still cited in numerous papers, Hypselorhachis is finally a diagnosed valid taxon. Now we need to find more of this animal than just a single vertebra.
Botella, H., Plasencia, P., Marquez-Aliaga, A., Cuny, G., and M. Dorka. 2009. Pseudodalatias henarejensis nov. sp. a new pseudodalatiid (Elasmobranchii) from the Middle Triassic of Spain. Journal of Vertebrate Paleontology 29:1006–1012. doi: 10.1671/039.029.0425
ABSTRACT—Pseudodalatiids, a chondrichthyan family of uncertain phylogenetic affinities, have been hitherto exclusively known from the tooth-based species Pseudodalatias barnstonensis (Sykes, 1971), which has a stratigraphic range restricted to the Upper Triassic of Europe. Pseudodalatias presents a characteristic dentition which allows it to hold and cut its prey, showing a neoselachian design, but lacking the triple-layered enameloid microstructure of neoselachian teeth. The discovery of Pseudodalatias henarejensis nov. sp. in the Ladinian of Spain extends the stratigraphical range and the palaeogeographical distribution of this family. This new species also demonstrates that a cutting-clutching dentition evolved progressively in the family Pseudodalatidiidae. Pseudodalatiids are likely to represent stem-batoids or stemneoselachians rather than aberrant hybodonts.
Kemp, T. S. 2009. The endocranial cavity of a nonmammalian eucynodont, Chiniquodon theotenicus, and its implications for the origin of the mammalian brain. Journal of Vertebrate Paleontology 29:1188–1198. doi: 10.1671/039.029.0430
ABSTRACT—The braincase and endocranial cavity of a specimen of a nonmammalian eucynodont Chiniquodon is described and illustrated, and a tentative reconstruction of the gross anatomy of the brain offered. Salient features are the well-developed impression for the olfactory lobes, the extreme narrowness of the region available for the telencephalon, and the evidence for a large cerebellum. A two-step theory for the origin of the mammalian brain is proposed. The first step is represented by the nonmammalian cynodont level and consisted of enlargement of the cerebellum and possibly midbrain structures. This stage is associated with the evolution of more sophisticated neuromuscular control of the mandibular and locomotory apparatuses. The second step was the evolution of the mammalian six-layered neocortex, and did not occur until the origin of the mammals themselves. This stage was an integral part of a complex set of allometric changes associated with miniaturization. The origin of the neocortex was correlated with sensitivity to higher frequency sound, and a greater area of olfactory epithelium, both expected to result from miniaturization, and also with the availability of increased space within the cranial cavity expected as the adductor jaw musculature was relatively reduced in mass. Overall, neocortical function was associated with the high energy nocturnal foraging activity generally believed to have appertained in the first mammals, and also sophisticated social communication.
Desojo, J. B., and A. B. Arcucci. 2009. New material of Luperosuchus fractus (Archosauria: Crurotarsi) from the Middle Triassic of Argentina: The earliest known South American 'rauisuchian'. Journal of Vertebrate Paleontology 29:1311–1315. doi: 10.1671/039.029.0422
-No abstract. This short communication redescribes the holotype and referred material of Luperosuchus and provides a modern diagnosis of the taxa. As stated by the authors rproviding modern dianoses and descriptions of material historically assigned to the 'Rauisuchia' is the first step leading to a detailed phylogenetic analysis of this group as most recent workers have hypothesized that it is paraphyletic in regards to the position of crocodylomorphs.
Lower Jurassic-
Barrett, P. M. 2009. A new basal sauropodomorph dinosaur from the Upper Elliot Formation (Lower Jurassic) of South Africa. Journal of Vertebrate Paleontology 29:1032–1045. doi: 10.1671/039.029.0401
ABSTRACT—A new basal sauropodomorph dinosaur, Massospondylus kaalae sp. nov., is named on the basis of a partial skull from the upper Elliot Formation (Lower Jurassic) of the Herschel District, South Africa. It can be distinguished from Massospondylus carinatus by a combination of character states relating to the proportions of the premaxilla, the presence of a strong ridge on the dorsolateral surface of the lacrimal, and the morphology of the braincase. The description of Massospondylus kaalae further increases sauropodomorph diversity in the previously depauperate upper Elliot fauna.
-one thing that caught my attention regarding this new taxon is that the species name honors a collection manager, a usually unheralded group when it comes to having taxa named after them. What a great honor and demonstration of the appreciation all researchers should have for the people who handle paleontological collections on a day to day basis.
Middle Triassic -
Butler, R. J., Barrett, P. M., Abel, R. L., and D. J. Gower. 2009. A possible ctenosauriscid archosaur from the Middle Triassic Manda beds of Tanzania. Journal of Vertebrate Paleontology 29:1022–1031. doi: 10.1671/039.029.0404
ABSTRACT—The Lifua Member of the Manda Beds of Tanzania (Middle Triassic: ?latest Anisian) has yielded an exceptionally important assemblage of early archosaurs, including numerous well-preserved specimens. However, the majority of this material has not been described formally, frustrating attempts to incorporate it into studies on early archosaur diversity and evolution. We describe an anterior dorsal vertebra from the Lifua Member as the holotype of a new taxon, Hypselorhachis mirabilis. Hypselorhachis is characterised by the possession of an elongate neural spine that is at least 5.5 times the height of the centrum, and can be diagnosed on the basis of a single autapomorphy relating to the morphology of the prezygapophysis. Hypselorhachis is similar to other early Middle Triassic archosaurs with elongate neural spines, including Arizonasaurus, Ctenosauriscus, and Lotosaurus. It is possible that these taxa form a clade, Ctenosauriscidae, but further anatomical and phylogenetic work is required before this can be confirmed.
-After more than 50 years of being a nomen nudum and still cited in numerous papers, Hypselorhachis is finally a diagnosed valid taxon. Now we need to find more of this animal than just a single vertebra.
Botella, H., Plasencia, P., Marquez-Aliaga, A., Cuny, G., and M. Dorka. 2009. Pseudodalatias henarejensis nov. sp. a new pseudodalatiid (Elasmobranchii) from the Middle Triassic of Spain. Journal of Vertebrate Paleontology 29:1006–1012. doi: 10.1671/039.029.0425
ABSTRACT—Pseudodalatiids, a chondrichthyan family of uncertain phylogenetic affinities, have been hitherto exclusively known from the tooth-based species Pseudodalatias barnstonensis (Sykes, 1971), which has a stratigraphic range restricted to the Upper Triassic of Europe. Pseudodalatias presents a characteristic dentition which allows it to hold and cut its prey, showing a neoselachian design, but lacking the triple-layered enameloid microstructure of neoselachian teeth. The discovery of Pseudodalatias henarejensis nov. sp. in the Ladinian of Spain extends the stratigraphical range and the palaeogeographical distribution of this family. This new species also demonstrates that a cutting-clutching dentition evolved progressively in the family Pseudodalatidiidae. Pseudodalatiids are likely to represent stem-batoids or stemneoselachians rather than aberrant hybodonts.
Kemp, T. S. 2009. The endocranial cavity of a nonmammalian eucynodont, Chiniquodon theotenicus, and its implications for the origin of the mammalian brain. Journal of Vertebrate Paleontology 29:1188–1198. doi: 10.1671/039.029.0430
ABSTRACT—The braincase and endocranial cavity of a specimen of a nonmammalian eucynodont Chiniquodon is described and illustrated, and a tentative reconstruction of the gross anatomy of the brain offered. Salient features are the well-developed impression for the olfactory lobes, the extreme narrowness of the region available for the telencephalon, and the evidence for a large cerebellum. A two-step theory for the origin of the mammalian brain is proposed. The first step is represented by the nonmammalian cynodont level and consisted of enlargement of the cerebellum and possibly midbrain structures. This stage is associated with the evolution of more sophisticated neuromuscular control of the mandibular and locomotory apparatuses. The second step was the evolution of the mammalian six-layered neocortex, and did not occur until the origin of the mammals themselves. This stage was an integral part of a complex set of allometric changes associated with miniaturization. The origin of the neocortex was correlated with sensitivity to higher frequency sound, and a greater area of olfactory epithelium, both expected to result from miniaturization, and also with the availability of increased space within the cranial cavity expected as the adductor jaw musculature was relatively reduced in mass. Overall, neocortical function was associated with the high energy nocturnal foraging activity generally believed to have appertained in the first mammals, and also sophisticated social communication.
Desojo, J. B., and A. B. Arcucci. 2009. New material of Luperosuchus fractus (Archosauria: Crurotarsi) from the Middle Triassic of Argentina: The earliest known South American 'rauisuchian'. Journal of Vertebrate Paleontology 29:1311–1315. doi: 10.1671/039.029.0422
-No abstract. This short communication redescribes the holotype and referred material of Luperosuchus and provides a modern diagnosis of the taxa. As stated by the authors rproviding modern dianoses and descriptions of material historically assigned to the 'Rauisuchia' is the first step leading to a detailed phylogenetic analysis of this group as most recent workers have hypothesized that it is paraphyletic in regards to the position of crocodylomorphs.
Lower Jurassic-
Barrett, P. M. 2009. A new basal sauropodomorph dinosaur from the Upper Elliot Formation (Lower Jurassic) of South Africa. Journal of Vertebrate Paleontology 29:1032–1045. doi: 10.1671/039.029.0401
ABSTRACT—A new basal sauropodomorph dinosaur, Massospondylus kaalae sp. nov., is named on the basis of a partial skull from the upper Elliot Formation (Lower Jurassic) of the Herschel District, South Africa. It can be distinguished from Massospondylus carinatus by a combination of character states relating to the proportions of the premaxilla, the presence of a strong ridge on the dorsolateral surface of the lacrimal, and the morphology of the braincase. The description of Massospondylus kaalae further increases sauropodomorph diversity in the previously depauperate upper Elliot fauna.
-one thing that caught my attention regarding this new taxon is that the species name honors a collection manager, a usually unheralded group when it comes to having taxa named after them. What a great honor and demonstration of the appreciation all researchers should have for the people who handle paleontological collections on a day to day basis.
Phytosaurs as the Likely Trackmaker for Apatopus from the Late Triassic of North America
Padian, K., Li, C., and J. Pchelnikova. 2009. The trackmaker of Apatopus (Late Triassic: North America): implications for the evolution of archosaur stance and gait. Palaeontology (early view). doi: 10.1111/j.1475-4983.2009.00924.x
Abstract - For some decades, a major focus of research has been on how locomotor modes changed in some archosaurian reptiles from a more or less ‘sprawling’ to an ‘erect’ posture, whether there were discrete intermediate stages, and how many times ‘erect’ posture evolved. The classic paradigm for the evolution of stance and gait in archosaurs, a three-stage transition from sprawling to ‘semi-erect’ to erect posture, has been replaced by a subtler understanding of a continuum of changing limb joint angles. We suggest a further separation of terminology related to stance vs. gait so as not to entail different processes: ‘sprawling’ and ‘erect’ should refer to continua of stance; ‘rotatory’ and ‘parasagittal’ are more appropriate ends of a continuum that describes the motions of gait. We show that the Triassic trackway Apatopus best fits the anatomy and proportions of phytosaurs, based on a new reconstruction of their foot skeleton; it is less likely to have been made by another pseudosuchian or nonarchosaurian archosauromorph. Moreover, the trackmaker was performing the high walk. A phytosaurian trackmaker would imply that the common ancestor of pseudosuchians, and therefore archosaurs could approximate the high walk (depending on phylogeny), and if so, erect stance and parasagittal gait did not evolve independently in pseudosuchians and ornithosuchians, although the kinematic mechanisms differed in the two groups. It remains to be seen how far outside Archosauria, if at all, more or less erect posture and parasagittal gait may have evolved.
Abstract - For some decades, a major focus of research has been on how locomotor modes changed in some archosaurian reptiles from a more or less ‘sprawling’ to an ‘erect’ posture, whether there were discrete intermediate stages, and how many times ‘erect’ posture evolved. The classic paradigm for the evolution of stance and gait in archosaurs, a three-stage transition from sprawling to ‘semi-erect’ to erect posture, has been replaced by a subtler understanding of a continuum of changing limb joint angles. We suggest a further separation of terminology related to stance vs. gait so as not to entail different processes: ‘sprawling’ and ‘erect’ should refer to continua of stance; ‘rotatory’ and ‘parasagittal’ are more appropriate ends of a continuum that describes the motions of gait. We show that the Triassic trackway Apatopus best fits the anatomy and proportions of phytosaurs, based on a new reconstruction of their foot skeleton; it is less likely to have been made by another pseudosuchian or nonarchosaurian archosauromorph. Moreover, the trackmaker was performing the high walk. A phytosaurian trackmaker would imply that the common ancestor of pseudosuchians, and therefore archosaurs could approximate the high walk (depending on phylogeny), and if so, erect stance and parasagittal gait did not evolve independently in pseudosuchians and ornithosuchians, although the kinematic mechanisms differed in the two groups. It remains to be seen how far outside Archosauria, if at all, more or less erect posture and parasagittal gait may have evolved.
A New Late Triassic Theropod, Tawa hallae, and its Implications for Early Dinosaur Evolution
A new Late Triassic basal theropod, Tawa hallae, is described by Nesbitt et al. (2009) in a new paper out today in Science. Tawa is known from two relatively complete skeletons and other isolated material from the Hayden Quarry at Ghost Ranch New Mexico [another link]. The Hayden Quarry is in the Petrified Forest Member of the Chinle Formation.
This quarry is an absolutely spectacular site that is proving to be the most diverse locality in the Chinle Formation, even more than the famed Coelophysis Quarry (which is close geographically but higher stratigraphically). Other taxa found at this site include Dromomeron romeri, Chindesaurus bryansmalli, Eucoelophysis baldwini, a coelophysoid theropod, and a shuvosaurid as well as various aetosaurs, crocodylomorphs, rauisuchians, phytosaurs, drepanosaurs, metoposaurs, and fish (Irmis et al. 2007).
Key points of the paper:
• Tawa possesses a mix of “coelophysoid” (Neotheropoda) and herrerasaurid characters that help clarify basal saurischian relationships.
Key points of the paper:
• Tawa possesses a mix of “coelophysoid” (Neotheropoda) and herrerasaurid characters that help clarify basal saurischian relationships.
- Herrerasaurids (Herrerasaurus, Chindesaurus, Staurikosaurus) and Eoraptor are unambiguously nested within Theropoda.
- Tawa is the sister taxon to Neotheropoda (see phylogenetic reconstruction artwork and tree below).
- Coelophysoidea is found to be paraphyletic, with the hypothesis that this clade had been serving as a “phylogenetic vacuum cleaner”, picking up deep theropod synapomorphies and ceratosaur/tetanuran reversals and treating them as coelophysoid synapomorphies.
• The presence of cervical pleurocoels in Tawa supports the hypothesis that cervical air sacs predate the origin of Neotheropoda and may be ancestral for Saurischia.
• The age of the Hayden Quarry (~215-213) and comparison with the Ischigualasto fauna supports the hypothesis of the diachronous evolution of Triassic dinosaur faunas.
• The presence of Dromomeron, Chindesaurus, Tawa, and a basal neotheropod in the Hayden Quarry suggests that the North American theropod fauna was not endemic, an was the result of several dispersals of taxa from South America.
• This prevalence of dispersal among early dinosaurs and other Triassic reptile groups indicates that physical barriers did not prevent these groups from moving around Pangaea - specifically into North America. Thus the question is why didn't sauropodomorphs and ornithischians make it to North America during the Triassic? Nesbitt et al. hypothesize that they were excluded by climate.
Dentary of Tawa hallae
Reconstruction of the head of Tawa hallae.
Articulated manus of Tawa hallae
In-situ articulated limbs of Tawa hallae
Associated dentary and maxilla of Tawa hallae
Block containing skull and other bones.
Thanks to Randy Irmis and Sterling Nesbitt for providing the photos and reconstructions used here. The reconstructions are by Jorge Gonzalez.
Links to some early news articles [here] [here] [here]
Link to National Science Foundation special report with lots of additional information on Tawa, its discovery, and its finders.
REFERENCES
Irmis, R. B, Nesbitt, S. J., Padian, K., Smith, N. D., Turner, A. H, Woody, D., and A. Downs. 2007. A Late Triassic dinosauromorph assemblage from New Mexico and the rise of dinosaurs. Science 317:358–361.
Nesbitt, S. J., Smith, N. D., Irmis, R. B., Turner, A. H., Downs, A., and M. A. Norell. 2009. A complete skeleton of a Late Triassic saurischian and the early evolution of dinosaurs. Science 326:1530-1533.
Paw-talk
This is an interesting site, includes a blog and also various forums ranging from everything such as wildlife conservation to pet care and grooming. Recently I was asked some questions regarding my work and blog for a blog post on this site. You can read my cheesy answers here. I also see that Matt Wedel (Ask Dr. Vector and SVPOW) also has an interview here. Brian Switek (Laelaps) also appears to be a regular contributor. Check it out.
Thanks to Ava for the invite.
Thanks to Ava for the invite.
In Memoriam Carl Gans (1923-2009)
CNAH ANNOUNCEMENT The Center for North American Herpetology Lawrence,
Kansas http://www.cnah.org 7 December 2009
IN MEMORIAM CARL GANS (1923-2009)
. . . modified from the New York Times
Dr. Carl Gans, 86, died peacefully after a long illness in Austin, Texas, on 30 November 2009. He was born in Hamburg, Germany, where he attended the Talmud Thora Realschule, and emigrated to the United States in 1939. Here he attended GeorgeWashington High School in New York City, received a Bachelor's Degree in Mechanical Engineering from New York University in 1944, a Master's Degree in Mechanical Engineering from Columbia University in 1950, a PE License from New York State in 1950, and a Doctoral Degree in Biology from Harvard in 1957. He served in the U.S. Army in the Pacific Command in the Philippines and Japan from 1944 to 1946. Carl was a John Simon Guggenheim Memorial Fellow from 1953 to 1955 conducting reptile studies in Brazil. After working eight years with Babcock & Wilcox installing power boilers, he changed careers and became a Professor of Biology and Department Chairperson at the University of Buffalo (later SUNY) from 1958 to 1971. He moved to Ann Arbor as Professor of Biology and Chairperson of Zoology at the University of Michigan until his retirement in 1998. Carl's work and hundreds of publications were in evolutionary physiology and comparative biomechanics. He carried out his primary studies in the area of reptiles and amphibians. He became world-known as editor of the journal "Morphology" for 25 years and as the editor of the monumental 23-volume "Biology of the Reptilia," published between 1969 and 2009. His first book-length publication was "Biomechanics" in which he combined his engineering and biology backgrounds. He co-authored two biology texts used in universities throughout the United States: "A Photographic Atlas of Shark Anatomy" and"Electromyography for Experimentalists." He also wrote the popular paperback book"Reptiles of the World," translated into many languages. His library of over 20,000 items in herpetology is currently at Ben Gurion University in Israel, which also has his extensive scientific correspondence. Other of his publications may be found at the Scripps Institute, University of California, San Diego, and the Museum of Comparative Zoology at Harvard. His extensive animal collections, which he gathered on five continents over many decades, can be found at the Field Museum of Natural History, Chicago, the California Academy of Sciences, San Francisco, the Carnegie Museum of Natural History, Pittsburg, and the Museum of Comparative Zoology at Harvard.
Carl was predeceased by his wife of fifty years, Mabel Kyoko Andow. He is survived by his brother Leo Gans of Teaneck, New Jersey.
*****
Memorial donations may be made to
THE CARL GANS AWARD
As some of you may be aware, we have been fund-raising for some time to endow the "Carl Gans Award," associated with the Division of Comparative Biomechanics, Society for Integrative and Comparative Biology (SICB). This award, recently approved by the SICB Executive Committee, is the first such award for the newly founded Division of Comparative Biomechanics and honors the numerous scientific and editorial contributions to biomechanics and herpetology by Carl Gans. To date, we have raised approximately two-thirds of the $25,000 required for endowment of this award. Fortunately, matching funds ($10,000) were generously made available by the late Carl Gans, his brother Leo Gans, and Sandy Gaunt that will provide a 2-for-1 match for the first $5000 contributed, no matter how small that, in conjunction with the matching offer, will let SICB takeadvantage of this new funding opportunity and enable the award to be established financially. Contributed funds should be marked for the "Carl Gans Award" and be sent to the attention of the SICB Executive Director, Brett Burk (BBurk@BurkInc.com) at the address below. He will deposit them into an account and reserve them for the fund. Send your contribution to:
Brett J. Burk SICB Executive Director 1313 Dolley Madison Boulevard, Suite 402 McLean, Virginia 22101
Contributions can also be made online at
https://ssl4.westserver.net/birenheide/secure/sicb/cart/donations.php
Kansas http://www.cnah.org 7 December 2009
IN MEMORIAM CARL GANS (1923-2009)
. . . modified from the New York Times
Dr. Carl Gans, 86, died peacefully after a long illness in Austin, Texas, on 30 November 2009. He was born in Hamburg, Germany, where he attended the Talmud Thora Realschule, and emigrated to the United States in 1939. Here he attended GeorgeWashington High School in New York City, received a Bachelor's Degree in Mechanical Engineering from New York University in 1944, a Master's Degree in Mechanical Engineering from Columbia University in 1950, a PE License from New York State in 1950, and a Doctoral Degree in Biology from Harvard in 1957. He served in the U.S. Army in the Pacific Command in the Philippines and Japan from 1944 to 1946. Carl was a John Simon Guggenheim Memorial Fellow from 1953 to 1955 conducting reptile studies in Brazil. After working eight years with Babcock & Wilcox installing power boilers, he changed careers and became a Professor of Biology and Department Chairperson at the University of Buffalo (later SUNY) from 1958 to 1971. He moved to Ann Arbor as Professor of Biology and Chairperson of Zoology at the University of Michigan until his retirement in 1998. Carl's work and hundreds of publications were in evolutionary physiology and comparative biomechanics. He carried out his primary studies in the area of reptiles and amphibians. He became world-known as editor of the journal "Morphology" for 25 years and as the editor of the monumental 23-volume "Biology of the Reptilia," published between 1969 and 2009. His first book-length publication was "Biomechanics" in which he combined his engineering and biology backgrounds. He co-authored two biology texts used in universities throughout the United States: "A Photographic Atlas of Shark Anatomy" and"Electromyography for Experimentalists." He also wrote the popular paperback book"Reptiles of the World," translated into many languages. His library of over 20,000 items in herpetology is currently at Ben Gurion University in Israel, which also has his extensive scientific correspondence. Other of his publications may be found at the Scripps Institute, University of California, San Diego, and the Museum of Comparative Zoology at Harvard. His extensive animal collections, which he gathered on five continents over many decades, can be found at the Field Museum of Natural History, Chicago, the California Academy of Sciences, San Francisco, the Carnegie Museum of Natural History, Pittsburg, and the Museum of Comparative Zoology at Harvard.
Carl was predeceased by his wife of fifty years, Mabel Kyoko Andow. He is survived by his brother Leo Gans of Teaneck, New Jersey.
*****
Memorial donations may be made to
THE CARL GANS AWARD
As some of you may be aware, we have been fund-raising for some time to endow the "Carl Gans Award," associated with the Division of Comparative Biomechanics, Society for Integrative and Comparative Biology (SICB). This award, recently approved by the SICB Executive Committee, is the first such award for the newly founded Division of Comparative Biomechanics and honors the numerous scientific and editorial contributions to biomechanics and herpetology by Carl Gans. To date, we have raised approximately two-thirds of the $25,000 required for endowment of this award. Fortunately, matching funds ($10,000) were generously made available by the late Carl Gans, his brother Leo Gans, and Sandy Gaunt that will provide a 2-for-1 match for the first $5000 contributed, no matter how small that, in conjunction with the matching offer, will let SICB takeadvantage of this new funding opportunity and enable the award to be established financially. Contributed funds should be marked for the "Carl Gans Award" and be sent to the attention of the SICB Executive Director, Brett Burk (BBurk@BurkInc.com) at the address below. He will deposit them into an account and reserve them for the fund. Send your contribution to:
Brett J. Burk SICB Executive Director 1313 Dolley Madison Boulevard, Suite 402 McLean, Virginia 22101
Contributions can also be made online at
https://ssl4.westserver.net/birenheide/secure/sicb/cart/donations.php
Osteology of the Middle Triassic Traversodontid Andescynodon
Liu, J., and J. Powell. 2009. Osteology of Andescynodon (Cynodontia:Traversodontidae) from the Middle Triassic of Argentina. American Museum Novitates 3674:1-19.
Abstract - All available specimens of Andescynodon mendozensis and Rusconiodon mignonei are examined and restudied, and the latter species is regarded as a junior synonym of the former. The postcranial skeleton of this species is described for the first time; it generally shows primitive features of traversodontids. Andescynodon mendozensis is a small- to medium-sized traversodontid characterized by 9~11 upper postcanines in adults (fewer in larger individuals), the transverse ridge of upper postcanines lying anteriorly on the tooth, paracanine fossa penetrating the skull roof in adult; it is differentiated from Pascualgnathus by relatively flatten skull, shorter and narrower temporal region, presence of four rather than three upper incisors.
Abstract - All available specimens of Andescynodon mendozensis and Rusconiodon mignonei are examined and restudied, and the latter species is regarded as a junior synonym of the former. The postcranial skeleton of this species is described for the first time; it generally shows primitive features of traversodontids. Andescynodon mendozensis is a small- to medium-sized traversodontid characterized by 9~11 upper postcanines in adults (fewer in larger individuals), the transverse ridge of upper postcanines lying anteriorly on the tooth, paracanine fossa penetrating the skull roof in adult; it is differentiated from Pascualgnathus by relatively flatten skull, shorter and narrower temporal region, presence of four rather than three upper incisors.
A Fun Book Is Now A Fun Exhibit
The Burke Museum of Natural History and Culture is excited to announce the opening of a new fossil exhibit. Cruisin’ the Fossil Freeway is an exhibit that brings together the best of the Burke Museum's fossil collection and the fossil-inspired artwork of celebrated artist Ray Troll to explore questions about evolution, extinction, and early life on Earth. The Burke Museum collaborated with artist Ray Troll and Seattle-born paleontologist Kirk Johnson to present this new exhibit exploring the abundance of fossils in our midst and how fossils shed light on Earth's past. Cruisin' the Fossil Freeway will travel nationally after closing in Seattle in late May 2010. The exhibit opens December 19. Please take a moment to visit the exhibits website at http://www.washington.edu/burkemuseum/cruisin/index.php.
Latest Literature - November 2009
Many recent and upcoming Triassic papers, mostly from Brazil.
Marynowski, L., and B. R. T. Simoneit. 2009. Widespread Upper Triassic to Lower Jurassic wildfire records from Poland:evidence from charcoal and pyrolytic polycyclic aromatic hydrocarbons. Palaios 24:785-798. DOI: 10.2110/palo.2009.p09-044r
Abstract - Laboratory tests indicate that 15% O2, instead of 12%, is required for the propagation of a widespread forest fire, a 3% increase from what was previously assumed. The presence of widespread wildfire records in the Upper Triassic and Lower Jurassic of Central Europe suggests that the lower limit for O2 during this time was at least 15%. Wildfire records are based on the co-occurrence of charcoal fragments and elevated concentrations of pyrolytic polycyclic aromatic hydrocarbons (PAHs). In all samples charcoal fragments are large to medium-sized and angular, suggesting that they were transported by rivers only short distances after charcoalification. Calculated combustion temperatures vary with stratigraphic position and average 295 377 uC, which is characteristic for ground or near-surface wildfires. The most extensive wildfires occurred in the earliest Jurassic and their intensities successively decreased with time. Average concentrations of the sum of pyrolytic PAHs for the lowermost Jurassic Zagaje Formation reached ~1253 mg/g total organic carbon (TOC), whereas for the Upper Triassic–Lower Jurassic Skłoby Formation they did not exceed ~16 mg/g TOC. Charcoal-bearing sequences were also characterized by the presence of phenyl-PAHs (Ph-PAHs) and oxygen-containing aromatic compounds. The dominance of the more stable Ph-PAH isomers in these immature to low-maturity sedimentary rocks supports their pyrolytic origin. The oxygenated PAHs may also be derived from combustion processes.
Veiga de Oliveira, T., Schultz, C. L., and M. B. Soares. 2009. A partial skeleton of Chiniquodon (Cynodontia, Chiniquodontidae) from the Brazilian Middle Triassic. Revista Brasileira de Paleontologia 12: 113-122. doi:10.4072/rbp.2009.2.02
Abstract - In this paper, we describe new postcranial remains of Chiniquodon cf. C. theotonicus, a chiniquodontid cynodont from the Therapsid Cenozone, from the Santa Maria Formation, Middle Triassic of Southern Brazil. In the described specimen are preserved almost all presacral vertebrae, the sacral vertebrae, an incomplete pelvic girdle, the left femur, and two metapodials. Some of these bones show slight differences relative to those already described for C. theotonicus, especially in the femur and in the pelvic girdle. Since the species can actually include the materials attributed to the genera Probelesodon (except from P. sanjuanensis) and Belesodon, however, these differences may represent normal ontogenetic variation in the species rather than being of taxonomically diagnostic value.
Stock Da-Rosa, A. A., Piniero, G., Dias-Da-Silva, S. Cisneros, J. C., Feltrin, F. F., and L. W. Neto. 2009. Bica São Tomé, a new fossiliferous site for the Lower Triassic of Southern Brazil. Revista Brasileira de Paleontologia 12:67-76. doi: 10.4072/rbp.2009.1.06
Abstract - Bica São Tomé, a new fossiliferous locality for the Sanga do Cabral Formation is described from southern Brazil. It consists in orange and reddish fine sandstones with sandy and calcareous concretions and intercalated fossiliferous intraformational conglomerates. This Lower Triassic locality is particularly interesting due to very well preserved and partially articulated specimens of continental tetrapods, an unusual feature in this unit, since the fossils in other outcrops are mostly disarticulated. Temnospondyl amphibians, procolophonoid and probable archosauromorph reptiles have been found in this new Lower Triassic locality. Further studies in this locality will allow the complement and a better acknowledged of the affinities of the Sanga do Cabral fauna with those from the basal Triassic Gondwanan and Laurasian.
De Amorim Arantes, B., Soares, M. B., and C. L. Schultz. 2009. Clevosaurus brasiliensis (Lepidosauria, Sphenodontia) from the Upper Triassic of Rio Grande do sul: post-cranial anatomy and phylogenetic relationships.Revista Brasileira de Paleontologia 12: 43-54. doi:10.4072/rbp.2009.1.04
Abstract - Sphenodontia is the most abundant taxon from the Caturrita Formation (Upper Triassic) paleofauna, which is composed predominantly by microvertebrates. However, only two syncrania (UFRGS-PV0613T e UFRGS-PV0748T) were formally described by Bonaparte & Sues in 2006 so far. Based on these materials, a new species Clevosaurus brasiliensis, was erected and the Clevosauridae family was formalized being composed by Clevosaurus, Brachyrhinodon and Polysphenodon. This work presents an anatomic description of the post-cranial skeleton of C. brasiliensis based on more than 25 specimens. Among the materials, dorsal, sacral and caudal vertebrae, femora, tibiae and fibulae were identified. Generally, the post-cranial skeleton presents the typical features of the sphenodontians, and the morphology of the bones is very similar to those of other species of Clevosaurus (e.g. C. hudsoni, C. bairdi). However, the adult individuals of the Brazilian species are notably smaller than most of the other sphenodontians. The anatomic information obtained was used, together with the cranial characters, in a phylogenetic analysis to establish the position of C. brasiliensis in the Sphenodontia clade. The data matrix was built with 18 taxa and 67 characters. The resulting cladogram confirms the close relationship between the Brazilian species with Clevosaurus hudsoni and attests the consistency of the Clevosauridae family.
Bardola, T. P., Schmidt, I. D., Sommer, M. G., and C. L. Schultz. 2009. Ginkgophyta wood in petrified forest of the Upper Triassic from Rio Grande do Sul, Brazil. Revista Brasileira de Paleontologia 12:139-148. doi:10.4072/rbp.2009.2.04
Abstract - The anatomic analysis of an assemblage of silicified fossil wood fragments from the Santa Maria Formation, southern Paraná Basin, Brazil, led to the identification of parameters compatible with the morphospecies Baieroxylon cicatricum, registered and described here for the first time for the Brazilian Gondwana. The secondary wood is homogeneous, picnoxylic and characterized by the presence of growth zones. In the radial walls of the tracheids there are bordered pits in a predominantly uniserial arrangement. Typical spiral thickening is present in longitudinal radial and tangential sections. The rays are in a uniserial arrangement and homogeneous. The cross-field pits, one to four per crossfield, are inconspicuous, circular, small and randomly arranged. Phloem and cortex are unpreserved. A common pattern found on the external surface of the wood fragments corresponds to simple eye-shaped scars, which would correspond to branch connections, and hollow, double and triple eye-shaped scars in alternating arrangement, which would correspond to leaf insertions.
Cabreira, S. F., and J. C. Cisneros. in press. Tooth histology of the parareptile Soturnia caliodon from the Upper Triassic of Rio Grande do Sul, Brazil. Acta Palaeontologica Polonica in press.
Abstract - A histological analysis of the dentition of the small procolophonid parareptile Soturnia caliodon reveals detailed information concerning tooth implantation and replacement for this taxon. The presence of acrodont tooth implantation is verified, which contradicts current models for procolophonid dentition. A heterogeneous enamel layer, that reaches large thickness on the cusps, and a broad secondary dentine are also recorded. These structures provide a very stable occlusal morphology that extends the useful life of the teeth. During the process of replacement, old teeth were not pushed out but reabsorbed. The evidence indicates that Soturnia caliodon had a very low rate of tooth replacement which constitutes a valuable adaptation for its high-fibre herbivorous niche.
Marynowski, L., and B. R. T. Simoneit. 2009. Widespread Upper Triassic to Lower Jurassic wildfire records from Poland:evidence from charcoal and pyrolytic polycyclic aromatic hydrocarbons. Palaios 24:785-798. DOI: 10.2110/palo.2009.p09-044r
Abstract - Laboratory tests indicate that 15% O2, instead of 12%, is required for the propagation of a widespread forest fire, a 3% increase from what was previously assumed. The presence of widespread wildfire records in the Upper Triassic and Lower Jurassic of Central Europe suggests that the lower limit for O2 during this time was at least 15%. Wildfire records are based on the co-occurrence of charcoal fragments and elevated concentrations of pyrolytic polycyclic aromatic hydrocarbons (PAHs). In all samples charcoal fragments are large to medium-sized and angular, suggesting that they were transported by rivers only short distances after charcoalification. Calculated combustion temperatures vary with stratigraphic position and average 295 377 uC, which is characteristic for ground or near-surface wildfires. The most extensive wildfires occurred in the earliest Jurassic and their intensities successively decreased with time. Average concentrations of the sum of pyrolytic PAHs for the lowermost Jurassic Zagaje Formation reached ~1253 mg/g total organic carbon (TOC), whereas for the Upper Triassic–Lower Jurassic Skłoby Formation they did not exceed ~16 mg/g TOC. Charcoal-bearing sequences were also characterized by the presence of phenyl-PAHs (Ph-PAHs) and oxygen-containing aromatic compounds. The dominance of the more stable Ph-PAH isomers in these immature to low-maturity sedimentary rocks supports their pyrolytic origin. The oxygenated PAHs may also be derived from combustion processes.
Veiga de Oliveira, T., Schultz, C. L., and M. B. Soares. 2009. A partial skeleton of Chiniquodon (Cynodontia, Chiniquodontidae) from the Brazilian Middle Triassic. Revista Brasileira de Paleontologia 12: 113-122. doi:10.4072/rbp.2009.2.02
Abstract - In this paper, we describe new postcranial remains of Chiniquodon cf. C. theotonicus, a chiniquodontid cynodont from the Therapsid Cenozone, from the Santa Maria Formation, Middle Triassic of Southern Brazil. In the described specimen are preserved almost all presacral vertebrae, the sacral vertebrae, an incomplete pelvic girdle, the left femur, and two metapodials. Some of these bones show slight differences relative to those already described for C. theotonicus, especially in the femur and in the pelvic girdle. Since the species can actually include the materials attributed to the genera Probelesodon (except from P. sanjuanensis) and Belesodon, however, these differences may represent normal ontogenetic variation in the species rather than being of taxonomically diagnostic value.
Stock Da-Rosa, A. A., Piniero, G., Dias-Da-Silva, S. Cisneros, J. C., Feltrin, F. F., and L. W. Neto. 2009. Bica São Tomé, a new fossiliferous site for the Lower Triassic of Southern Brazil. Revista Brasileira de Paleontologia 12:67-76. doi: 10.4072/rbp.2009.1.06
Abstract - Bica São Tomé, a new fossiliferous locality for the Sanga do Cabral Formation is described from southern Brazil. It consists in orange and reddish fine sandstones with sandy and calcareous concretions and intercalated fossiliferous intraformational conglomerates. This Lower Triassic locality is particularly interesting due to very well preserved and partially articulated specimens of continental tetrapods, an unusual feature in this unit, since the fossils in other outcrops are mostly disarticulated. Temnospondyl amphibians, procolophonoid and probable archosauromorph reptiles have been found in this new Lower Triassic locality. Further studies in this locality will allow the complement and a better acknowledged of the affinities of the Sanga do Cabral fauna with those from the basal Triassic Gondwanan and Laurasian.
De Amorim Arantes, B., Soares, M. B., and C. L. Schultz. 2009. Clevosaurus brasiliensis (Lepidosauria, Sphenodontia) from the Upper Triassic of Rio Grande do sul: post-cranial anatomy and phylogenetic relationships.Revista Brasileira de Paleontologia 12: 43-54. doi:10.4072/rbp.2009.1.04
Abstract - Sphenodontia is the most abundant taxon from the Caturrita Formation (Upper Triassic) paleofauna, which is composed predominantly by microvertebrates. However, only two syncrania (UFRGS-PV0613T e UFRGS-PV0748T) were formally described by Bonaparte & Sues in 2006 so far. Based on these materials, a new species Clevosaurus brasiliensis, was erected and the Clevosauridae family was formalized being composed by Clevosaurus, Brachyrhinodon and Polysphenodon. This work presents an anatomic description of the post-cranial skeleton of C. brasiliensis based on more than 25 specimens. Among the materials, dorsal, sacral and caudal vertebrae, femora, tibiae and fibulae were identified. Generally, the post-cranial skeleton presents the typical features of the sphenodontians, and the morphology of the bones is very similar to those of other species of Clevosaurus (e.g. C. hudsoni, C. bairdi). However, the adult individuals of the Brazilian species are notably smaller than most of the other sphenodontians. The anatomic information obtained was used, together with the cranial characters, in a phylogenetic analysis to establish the position of C. brasiliensis in the Sphenodontia clade. The data matrix was built with 18 taxa and 67 characters. The resulting cladogram confirms the close relationship between the Brazilian species with Clevosaurus hudsoni and attests the consistency of the Clevosauridae family.
Bardola, T. P., Schmidt, I. D., Sommer, M. G., and C. L. Schultz. 2009. Ginkgophyta wood in petrified forest of the Upper Triassic from Rio Grande do Sul, Brazil. Revista Brasileira de Paleontologia 12:139-148. doi:10.4072/rbp.2009.2.04
Abstract - The anatomic analysis of an assemblage of silicified fossil wood fragments from the Santa Maria Formation, southern Paraná Basin, Brazil, led to the identification of parameters compatible with the morphospecies Baieroxylon cicatricum, registered and described here for the first time for the Brazilian Gondwana. The secondary wood is homogeneous, picnoxylic and characterized by the presence of growth zones. In the radial walls of the tracheids there are bordered pits in a predominantly uniserial arrangement. Typical spiral thickening is present in longitudinal radial and tangential sections. The rays are in a uniserial arrangement and homogeneous. The cross-field pits, one to four per crossfield, are inconspicuous, circular, small and randomly arranged. Phloem and cortex are unpreserved. A common pattern found on the external surface of the wood fragments corresponds to simple eye-shaped scars, which would correspond to branch connections, and hollow, double and triple eye-shaped scars in alternating arrangement, which would correspond to leaf insertions.
Cabreira, S. F., and J. C. Cisneros. in press. Tooth histology of the parareptile Soturnia caliodon from the Upper Triassic of Rio Grande do Sul, Brazil. Acta Palaeontologica Polonica in press.
Abstract - A histological analysis of the dentition of the small procolophonid parareptile Soturnia caliodon reveals detailed information concerning tooth implantation and replacement for this taxon. The presence of acrodont tooth implantation is verified, which contradicts current models for procolophonid dentition. A heterogeneous enamel layer, that reaches large thickness on the cusps, and a broad secondary dentine are also recorded. These structures provide a very stable occlusal morphology that extends the useful life of the teeth. During the process of replacement, old teeth were not pushed out but reabsorbed. The evidence indicates that Soturnia caliodon had a very low rate of tooth replacement which constitutes a valuable adaptation for its high-fibre herbivorous niche.
Anatomy of the Late Triassic Ornithischian Eocursor parvus
Richard Butler's full description of the early ornithischian Eocursor parvus is now available online in the Zoological Journal of the Linnaean Society. As detailed by Richard, this taxon is of importance not only because of its phylogenetic position, but also because it represents only one of three purported ornithischian specimens from the Triassic Period and is the best preserved.
Unlike Pisanosaurus and the unnamed jaw fragment from Argentina assigned to the Heterodontosauridae, Eocursor can clearly be demonstrated to be a bona fide ornithischian. The potential problem with this specimen, and outlined in the paper, is debate on the stratigraphic position and thus the age of the specimen. There is indeed the possibility that this specimen may actually be Jurassic in age and hopefully some future studies on the provenance and age of the specimen can be done to verify the age. Splitting hairs? Maybe, but the exact age is very important when looking at tempo and mode of early dinosaur evolution. When you only have three physical specimens of a group from a specific time period, each one is of the utmost importance.
Nonetheless, this is still an extremely important specimen and congratulations to Richard on another solid contribution to vertebrate paleontology and early dinosaur studies.
Butler, R. J. 2009. The anatomy of the basal ornithischian dinosaur Eocursor parvus from the lower Elliot Formation(Late Triassic) of South Africa. Zoological Journal of the Linnaean Society. Published early online, doi: 10.1111/j.1096-3642.2009.00631.x
Abstract - Ornithischia is a morphologically and taxonomically diverse clade of dinosaurs that originated during the Late Triassic and were the dominant large-bodied herbivores in many Cretaceous ecosystems. The early evolution of ornithischian dinosaurs is poorly understood, as a result in part of a paucity of fossil specimens, particularly during the Triassic. The most complete Triassic ornithischian dinosaur yet discovered is Eocursor parvus from the lower Elliot Formation (Late Triassic: Norian–Rhaetian) of Free State, South Africa, represented by a partial skull and relatively complete postcranial skeleton. Here, the anatomy of Eocursor is described in detail for the first time, and detailed comparisons are provided to other basal ornithischian taxa. Eocursor is a small-bodied taxon (approximately 1 m in length) that possesses a plesiomorphic dentition consisting of unworn leaf-shaped crowns, a proportionally large manus with similarities to heterodontosaurids, a pelvis that contains an intriguing mix of plesiomorphic and derived character states, and elongate distal hindlimbs suggesting well-developed cursorial ability. The ontogenetic status of the holotype material is uncertain. Eocursor may represent the sister taxon to Genasauria, the clade that includes most of ornithischian diversity, although this phylogenetic position is partially dependent upon the uncertain phylogenetic position of the enigmatic and controversial clade Heterodontosauridae.
Unlike Pisanosaurus and the unnamed jaw fragment from Argentina assigned to the Heterodontosauridae, Eocursor can clearly be demonstrated to be a bona fide ornithischian. The potential problem with this specimen, and outlined in the paper, is debate on the stratigraphic position and thus the age of the specimen. There is indeed the possibility that this specimen may actually be Jurassic in age and hopefully some future studies on the provenance and age of the specimen can be done to verify the age. Splitting hairs? Maybe, but the exact age is very important when looking at tempo and mode of early dinosaur evolution. When you only have three physical specimens of a group from a specific time period, each one is of the utmost importance.
Nonetheless, this is still an extremely important specimen and congratulations to Richard on another solid contribution to vertebrate paleontology and early dinosaur studies.
Butler, R. J. 2009. The anatomy of the basal ornithischian dinosaur Eocursor parvus from the lower Elliot Formation(Late Triassic) of South Africa. Zoological Journal of the Linnaean Society. Published early online, doi: 10.1111/j.1096-3642.2009.00631.x
Abstract - Ornithischia is a morphologically and taxonomically diverse clade of dinosaurs that originated during the Late Triassic and were the dominant large-bodied herbivores in many Cretaceous ecosystems. The early evolution of ornithischian dinosaurs is poorly understood, as a result in part of a paucity of fossil specimens, particularly during the Triassic. The most complete Triassic ornithischian dinosaur yet discovered is Eocursor parvus from the lower Elliot Formation (Late Triassic: Norian–Rhaetian) of Free State, South Africa, represented by a partial skull and relatively complete postcranial skeleton. Here, the anatomy of Eocursor is described in detail for the first time, and detailed comparisons are provided to other basal ornithischian taxa. Eocursor is a small-bodied taxon (approximately 1 m in length) that possesses a plesiomorphic dentition consisting of unworn leaf-shaped crowns, a proportionally large manus with similarities to heterodontosaurids, a pelvis that contains an intriguing mix of plesiomorphic and derived character states, and elongate distal hindlimbs suggesting well-developed cursorial ability. The ontogenetic status of the holotype material is uncertain. Eocursor may represent the sister taxon to Genasauria, the clade that includes most of ornithischian diversity, although this phylogenetic position is partially dependent upon the uncertain phylogenetic position of the enigmatic and controversial clade Heterodontosauridae.
The Osteology and Relationships of Vancleavea campi (Reptilia: Archosauriformes)
Um...OK, this came out a bit earlier than I expected and is now available online from the Journal of the Linnaean Society. This is the long awaited full description of this taxon, which supersedes my 2008 publication which came out when this paper was in press and therefore not cited. Sterling felt that the new PEFO material should be dealt with in a separate publication, but unfortunately I did not get it out in time for him to use, and to ask him and his coauthors to go back through this manuscript in the proof stages and add info from my paper would have been too much. So we are left with a weird case in which two papers come out on the same taxon and neither cite each other, but I assure you that we were all aware of each other's work before anyone questions ethics. Sterling did compare the GR material to one of the PEFO specimens; whereas I did not describe or code any of the Ghost Ranch material, thus this new paper is up to date in that regard. 
I guarantee you that this is one of the most bizarre archosauriforms you may ever encounter, see the above reconstruction courtesy of Sterling Nesbitt. Enigmatic since its initial discovery in 1962 (from Petrified Forest National Park) and initial description by Long and Murry in 1995, recent collection of better specimens has elucidated its osteology and broader relationships. Vancleavea is actually common at most levels of the Chinle Formation; however, due to the scrappy nature of most of the materials it is difficult to compare specimens across stratigraphic levels. Are we looking at one species or several? I congratulate Sterling, Michelle, Bryan, and Alex on a great discovery and paper.
Nesbitt, S. J., Stocker, M. R., Small, B. J., and A. Downs. 2009. The osteology and relationships of Vancleavea campi(Reptilia: Archosauriformes). Zoological Journal of the Linnaean Society 157:814–864 doi: 10.1111/j.1096-3642.2009.00530.x
Vancleavea campi Long & Murry, 1995, from the Late Triassic of western North America, represents the latest surviving non-archosaurian archosauriform known to date. We present here a detailed comparative description based on a nearly complete, articulated skeleton from the Coelophysis Quarry in north-central New Mexico and other fragmentary specimens. The unique combination of morphological features of Vancleavea is unparalleled within Reptilia; it has four unique morphologies of imbricated osteoderms covering the entire body, a short, highly ossified skull, relatively small limbs and morphological features consistent with a semi-aquatic lifestyle. Vancleavea is placed in a rigorous phylogenetic analysis examining the relationships of non-archosaurian archosauriforms, and is found to be more closely related to Archosauria than both Erythrosuchus and Proterosuchus, but outside of the crown group. The analysis confirms previously hypothesized relationships, which found Euparkeria to be the closest sister taxon of Archosauria. It is not clear whether specimens referred to Vancleavea campi represent a single species-level taxon or a clade of closely related taxa that lived through much of the Late Triassic of North America, given the poor fossil record of the taxon.
I guarantee you that this is one of the most bizarre archosauriforms you may ever encounter, see the above reconstruction courtesy of Sterling Nesbitt. Enigmatic since its initial discovery in 1962 (from Petrified Forest National Park) and initial description by Long and Murry in 1995, recent collection of better specimens has elucidated its osteology and broader relationships. Vancleavea is actually common at most levels of the Chinle Formation; however, due to the scrappy nature of most of the materials it is difficult to compare specimens across stratigraphic levels. Are we looking at one species or several? I congratulate Sterling, Michelle, Bryan, and Alex on a great discovery and paper.
Nesbitt, S. J., Stocker, M. R., Small, B. J., and A. Downs. 2009. The osteology and relationships of Vancleavea campi(Reptilia: Archosauriformes). Zoological Journal of the Linnaean Society 157:814–864 doi: 10.1111/j.1096-3642.2009.00530.x
Vancleavea campi Long & Murry, 1995, from the Late Triassic of western North America, represents the latest surviving non-archosaurian archosauriform known to date. We present here a detailed comparative description based on a nearly complete, articulated skeleton from the Coelophysis Quarry in north-central New Mexico and other fragmentary specimens. The unique combination of morphological features of Vancleavea is unparalleled within Reptilia; it has four unique morphologies of imbricated osteoderms covering the entire body, a short, highly ossified skull, relatively small limbs and morphological features consistent with a semi-aquatic lifestyle. Vancleavea is placed in a rigorous phylogenetic analysis examining the relationships of non-archosaurian archosauriforms, and is found to be more closely related to Archosauria than both Erythrosuchus and Proterosuchus, but outside of the crown group. The analysis confirms previously hypothesized relationships, which found Euparkeria to be the closest sister taxon of Archosauria. It is not clear whether specimens referred to Vancleavea campi represent a single species-level taxon or a clade of closely related taxa that lived through much of the Late Triassic of North America, given the poor fossil record of the taxon.
Cruxicheiros newmanorum, a new Middle Jurassic Theropod from England
Benson, R. B. J., and J. D. Radley. in press. A new large-bodied theropod dinosaur from the Middle Jurassic of Warwickshire, United Kingdom. Acta Palaeontologica Polonica, available online 20 Nov 2009.
Abstract - Previously undocumented postcranial material from the Chipping Norton Limestone Formation (Middle Jurassic: Lower Bathonian) of Cross Hands Quarry, near Little Compton, Warwickshire represents a new large-bodied theropod dinosaur, distinct from the contemporaneous Megalosaurus bucklandii. Cruxicheiros newmanorum gen. et sp. nov. is diagnosed by a single autapomorphy, the presence of a proximomedially inclined ridge within the groove that marks the lateral extent of the posterior flange of the femoral caput (trochanteric fossa). C. newmanorum shows three tetanuran features: widely separated cervical zygapophyses, a swollen ridge on the lateral surface of the iliac blade and an anterior spur of the caudal neural spines. However, due to fragmentary preservation its affinities within Tetanurae remain uncertain: phylogenetic analysis places it as the most basal tetanuran, the most basal megalosauroid (= spinosauroid) or the most basal neotetanuran.
Abstract - Previously undocumented postcranial material from the Chipping Norton Limestone Formation (Middle Jurassic: Lower Bathonian) of Cross Hands Quarry, near Little Compton, Warwickshire represents a new large-bodied theropod dinosaur, distinct from the contemporaneous Megalosaurus bucklandii. Cruxicheiros newmanorum gen. et sp. nov. is diagnosed by a single autapomorphy, the presence of a proximomedially inclined ridge within the groove that marks the lateral extent of the posterior flange of the femoral caput (trochanteric fossa). C. newmanorum shows three tetanuran features: widely separated cervical zygapophyses, a swollen ridge on the lateral surface of the iliac blade and an anterior spur of the caudal neural spines. However, due to fragmentary preservation its affinities within Tetanurae remain uncertain: phylogenetic analysis places it as the most basal tetanuran, the most basal megalosauroid (= spinosauroid) or the most basal neotetanuran.
Galileo's Fingers Reportedly Resurface After a Century
Interesting, yet slightly bizarre, story out today. Especially the part that discusses how this type of dismemberment is commonly done with Catholic saints, whose body parts purportedly possess sacred powers.
http://www.cnn.com/2009/WORLD/europe/11/23/galileo.fingers/index.html
BTW...doesn't "Galileo's Fingers" sound like a good name for a rock band?
http://www.cnn.com/2009/WORLD/europe/11/23/galileo.fingers/index.html
BTW...doesn't "Galileo's Fingers" sound like a good name for a rock band?
Petrified Forest Landmarks - Eagle Nest Rock
For the first 35 years of its existence as a National Monument, one of the major attractions of the Petrified Forest was Eagle Nest Rock in Jasper Forest. As seen below in an undated National Park Service photo. Eagle Nest Rock was a erosional pillar of sandstone in the Jasper Forest bed of the Sonsela Member (Chinle Formation).
The photo [NPS] below is a closer view, showing how remarkable (and delicate) this feature was. It stood about 15 feet (5 meters) tall.
A gravel road detoured off of the main park road and wound its way through the Jasper Forest (numerous petrified logs) turned to the southwest and at its terminus curved around Eagle Nest Rock.
This was a very popular attraction and visitors (and park rangers) would climb up and have their photo taken next to the pillar. The photo [courtesy of the UCMP]. below was taken of Clyde Polacca (of the Hopi Reservation) in 1923 by Charles L. Camp during his paleontological research of the Petrified Forest area
Sadly Eagle Nest Rock "landmark in the First Forest, fell January 25 and 26 [1941] following a month of considerable rain and some high winds.” - Howard R. Stagner, monthly naturalist report.
The old Jasper Forest road was closed afterwards to protect fossil resources (petrified wood) and now only an overlook exists from which you cannot see the Eagle Nest Rock site. The old road was never removed and you can still follow it today. Below is a reshoot of Camp's photo from 2006.
New Blog
Back at the beginning of the year I had this post on my American Civil War interests. Much of this stems from the letters and diary I have from an ancestor who fought in the war. I've been researching these letters and his regiment for almost 20 years now in hopes of someday putting it in book form. I've realized that this is not going to happen anytime soon, so what I have decided to do in the meantime is put portions of this research in blog form to share with other enthusiasts.
So I am happy to announce the launch of a new blog titled "three month men" which essentially is a study of the First Connecticut Volunteer Regiment in the American Civil War, chiefly through the words of one of the participants. What will be presented is my ancestor's role in the American Civil War, portraying events from the end of 1860 through the days after the First Battle of Bull Run in April of 1861. I will present excerpts from his diary and letters and the posts will be ordered chronologically and cover a day or two of time. Thus I hope that people will be interested in following his story as the blog progresses. Furthermore, I hope to provide information on a poorly known military unit. As this will truly be a side project I hope to post new material once a week or biweekly. If any of my Triassic readers have a soft spot for American history, in particular the Civil War, I welcome you to follow along. I hope that you will find it of interest.
www.threemonthmen.blogspot.com
So I am happy to announce the launch of a new blog titled "three month men" which essentially is a study of the First Connecticut Volunteer Regiment in the American Civil War, chiefly through the words of one of the participants. What will be presented is my ancestor's role in the American Civil War, portraying events from the end of 1860 through the days after the First Battle of Bull Run in April of 1861. I will present excerpts from his diary and letters and the posts will be ordered chronologically and cover a day or two of time. Thus I hope that people will be interested in following his story as the blog progresses. Furthermore, I hope to provide information on a poorly known military unit. As this will truly be a side project I hope to post new material once a week or biweekly. If any of my Triassic readers have a soft spot for American history, in particular the Civil War, I welcome you to follow along. I hope that you will find it of interest.
www.threemonthmen.blogspot.com
Ectothermic Bovids? Is Nothing Sacred?
OK...this is pretty far out from the Triassic, but really interesting so I thought I'd share.
Kohler, M., and S. Moya-Sola. 2009. Physiological and life history strategies of a fossil large mammal in a resource-limited environment. Early online, PNAS. doi: 10.1073/pnas.0813385106
Abstract - Because of their physiological and life history characteristics, mammals exploit adaptive zones unavailable to ectothermic reptiles. Yet, they perform best in energy-rich environments because their high and constant growth rates and their sustained levels of resting metabolism require continuous resource supply. In resource limited ecosystems such as islands, therefore, reptiles frequently displace mammals because their slow and flexible growth rates and low metabolic rates permit them to operate effectively with low energy flow. An apparent contradiction of this general principle is the long-term persistence of certain fossil large mammals on energy-poor Mediterranean islands. The purpose of the present study is to uncover the developmental and physiological strategies that allowed fossil large mammals to cope with the low levels of resource supply that characterize insular ecosystems. Long-bone histology of Myotragus, a Plio-Pleistocene bovid from the Balearic Islands, reveals lamellar-zonal tissue throughout the cortex, a trait exclusive to ectothermic reptiles. The bone microstructure indicates that Myotragus grew unlike any other mammal but similar to crocodiles at slow and flexible rates, ceased growth periodically, and attained somatic maturity extremely late by ~12 years. This developmental pattern denotes that Myotragus, much like extant reptiles, synchronized its metabolic requirements with fluctuating resource levels. Our results suggest that developmental and physiological plasticity was crucial to the survival of this and, perhaps, other large mammals on resource-limited Mediterranean Islands, yet it eventually led to their extinction through a major predator, Homo sapiens.
This is open access from:
www.pnas.orgcgidoi10.1073pnas.0813385106
Kohler, M., and S. Moya-Sola. 2009. Physiological and life history strategies of a fossil large mammal in a resource-limited environment. Early online, PNAS. doi: 10.1073/pnas.0813385106
Abstract - Because of their physiological and life history characteristics, mammals exploit adaptive zones unavailable to ectothermic reptiles. Yet, they perform best in energy-rich environments because their high and constant growth rates and their sustained levels of resting metabolism require continuous resource supply. In resource limited ecosystems such as islands, therefore, reptiles frequently displace mammals because their slow and flexible growth rates and low metabolic rates permit them to operate effectively with low energy flow. An apparent contradiction of this general principle is the long-term persistence of certain fossil large mammals on energy-poor Mediterranean islands. The purpose of the present study is to uncover the developmental and physiological strategies that allowed fossil large mammals to cope with the low levels of resource supply that characterize insular ecosystems. Long-bone histology of Myotragus, a Plio-Pleistocene bovid from the Balearic Islands, reveals lamellar-zonal tissue throughout the cortex, a trait exclusive to ectothermic reptiles. The bone microstructure indicates that Myotragus grew unlike any other mammal but similar to crocodiles at slow and flexible rates, ceased growth periodically, and attained somatic maturity extremely late by ~12 years. This developmental pattern denotes that Myotragus, much like extant reptiles, synchronized its metabolic requirements with fluctuating resource levels. Our results suggest that developmental and physiological plasticity was crucial to the survival of this and, perhaps, other large mammals on resource-limited Mediterranean Islands, yet it eventually led to their extinction through a major predator, Homo sapiens.
This is open access from:
www.pnas.orgcgidoi10.1073pnas.0813385106
Aardonyx celestae, a New Transistional Sauropodomorph from the Early Jurassic of South Africa
Yates, A. M., Bonnan, M. F., Neveling, J., Chinsamy, A., and M. G. Blackbeard. 2009. A new transitional sauropodomorph dinosaur from the Early Jurassic of South Africa and the evolution of sauropod feeding and quadrupedalism. Proceedings of the Royal Society B. doi:10.1098/rspb.2009.1440. Published online
Abstract - Aardonyx celestae gen. et sp. nov. is described from the upper Elliot Formation (Early Jurassic)of South Africa. It can be diagnosed by autapomorphies of the skull, particularly the jaws, cervical column, forearm and pes. It is found to be the sister group of a clade of obligatory quadrupedal sauropodomorphs (Melanorosaurus + Sauropoda) and thus lies at the heart of the basal sauropodomorph–sauropod transition. The narrow jaws of A. celestae retain a pointed symphysis but appear to have lacked fleshy cheeks. Broad, U-shaped jaws were previously thought to have evolved prior to the loss of gape-restricting cheeks. However, the narrow jaws of A. celestae retain a pointed symphysis but appear to have lacked fleshy cheeks, demonstrating unappreciated homoplasy in the evolution of the sauropod bulk-browsing apparatus. The limbs of A. celestae indicate that it retained a habitual bipedal gait although incipient characters associated with the pronation of the manus and the adoption of a quadrupedal gait are evident through geometric morphometric analysis (using thin-plate splines) of the ulna and femur. Cursorial ability appears to have been reduced and the weight bearing axis of the pes shifted to a medial, entaxonic position, falsifying the hypothesis that entaxony evolved in sauropods only after an obligate quadrupedal gait had been adopted.
Abstract - Aardonyx celestae gen. et sp. nov. is described from the upper Elliot Formation (Early Jurassic)of South Africa. It can be diagnosed by autapomorphies of the skull, particularly the jaws, cervical column, forearm and pes. It is found to be the sister group of a clade of obligatory quadrupedal sauropodomorphs (Melanorosaurus + Sauropoda) and thus lies at the heart of the basal sauropodomorph–sauropod transition. The narrow jaws of A. celestae retain a pointed symphysis but appear to have lacked fleshy cheeks. Broad, U-shaped jaws were previously thought to have evolved prior to the loss of gape-restricting cheeks. However, the narrow jaws of A. celestae retain a pointed symphysis but appear to have lacked fleshy cheeks, demonstrating unappreciated homoplasy in the evolution of the sauropod bulk-browsing apparatus. The limbs of A. celestae indicate that it retained a habitual bipedal gait although incipient characters associated with the pronation of the manus and the adoption of a quadrupedal gait are evident through geometric morphometric analysis (using thin-plate splines) of the ulna and femur. Cursorial ability appears to have been reduced and the weight bearing axis of the pes shifted to a medial, entaxonic position, falsifying the hypothesis that entaxony evolved in sauropods only after an obligate quadrupedal gait had been adopted.
Defining Silesauridae
The new paper by Max Langer and collaborators (Langer et al., 2009) provides a phylogenetic definition for the clade Silesauridae. Silesaurids are gracile, quadrupedal, hebivorous/omnivorous dinosauriforms whose first announcement in 2003 (Dzik, 2003) generated a large amount of interest in early dinosaur phylogeny. In fact there were at least five presentations at this years SVP meeting alone that dealt with silesaurs.
Langer et al. (2009) define Silesauridae as "all archosaurs closer to Silesaurus opolensis, than to Heterodontosaurus tucki and Marasuchus lilloensis". Currently it is pretty much agreed that Silesauridae contains Silesaurus opolensis, Sacisaurus agudoensis, Eucoelophysis baldwini, and Pseudolagosuchus major (Nesbitt et al., 2005; Ezcurra, 2006; Irmis et al., 2007b; Langer et al., 2009). Silesaurus also possibly contains Lewisuchus admixtus, Technosaurus smalli, and an isolated specimen from Petrified Forest National Park (Irmis et al., 2005; Parker et al., 2006; Nesbitt et al., 2007; Langer et al., 2009).
Since their first publication it has been debated whether this clade represent dinosauriforms (e.g., Parker et al., 2006; Irmis et al., 2007a; Nesbitt et al., 2007) or possibly basal ornithischians (e.g., Ferigolo and Langer, 2007; Dzik and Sulej, 2007). Currently there is much more support for placement as the sister taxon of Dinosauria (Ezcurra, 2006; Irmis et al. 2007b, Langer et al., 2009). Nonetheless, silesaurids most likely filled an ecological niche later filled by ornithischian and thus possibly supressed early ornithischian diversity through the Late Triassic.
REFERENCES
Dzik, J. 2003. A beaked herbivorous archosaur with dinosaur affinities from the early Late Triassic of Poland. Journal of Vertebrate Paleontology 23:556-574.
Dzik, J., and T. Sulej. 2007. A review of the Early Triassic Krasiejow biota from Silesia, Poland. Paleontologia Polonica 64:3-27.
Ezcurra, M. D. 2006. A review of the systematic position of the dinosauriform archosaur Eucoelophysis baldwini from the Upper Triassic of New Mexico, U.S.A. Geodiversitas 28:649-684.
Ferigolo, J. and M. Langer. 2007. A late Triassic dinosauriform from south Brazil and the origin of the ornithischian predentary bone. Historical Biology 19:23-33.
Irmis, R. B., Parker, W. G., and S. N. Nesbitt, 2005. Critical review of the Late Triassic dinosaur record, part 2: Ornithischia. Society of Vertebrate Paleontology 25(3):73A.
Irmis, R. B., Parker, W. G., Nesbitt, S. J., and J. Liu, 2007. Early ornithischian dinosaurs: the Triassic Record. Historical Biology 19:3-22.
Irmis, R. B., Nesbitt, S. J., Padian, K., Smith, N. D., Turner, A. H., Woody, D., and A. Downs. 2007. A Late Triassic dinosauromorph assemblage from New Mexico and the rise of dinosaurs. Science 317:358-361.
Nesbitt, S. N., Irmis, R. B., and W. G. Parker, 2005. Critical review of the Late Triassic dinosaur record, part 3: Saurischians of North America. Society of Vertebrate Paleontology 25(3):96A.
Nesbitt, S. J., Irmis, R. B., and W. G. Parker. 2007. A critical reevaluation of the Late Triassic dinosaur taxa of North America. Journal of Systematic Palaeontology 5:209-243.
Parker, W. G., Irmis, R. B., and S. J. Nesbitt. 2006. Review of the Late Triassic dinosaur record from Petrified Forest National Park, Arizona. Museum of Northern Arizona Bulletin 62:160-161.
Langer et al. (2009) define Silesauridae as "all archosaurs closer to Silesaurus opolensis, than to Heterodontosaurus tucki and Marasuchus lilloensis". Currently it is pretty much agreed that Silesauridae contains Silesaurus opolensis, Sacisaurus agudoensis, Eucoelophysis baldwini, and Pseudolagosuchus major (Nesbitt et al., 2005; Ezcurra, 2006; Irmis et al., 2007b; Langer et al., 2009). Silesaurus also possibly contains Lewisuchus admixtus, Technosaurus smalli, and an isolated specimen from Petrified Forest National Park (Irmis et al., 2005; Parker et al., 2006; Nesbitt et al., 2007; Langer et al., 2009).
Since their first publication it has been debated whether this clade represent dinosauriforms (e.g., Parker et al., 2006; Irmis et al., 2007a; Nesbitt et al., 2007) or possibly basal ornithischians (e.g., Ferigolo and Langer, 2007; Dzik and Sulej, 2007). Currently there is much more support for placement as the sister taxon of Dinosauria (Ezcurra, 2006; Irmis et al. 2007b, Langer et al., 2009). Nonetheless, silesaurids most likely filled an ecological niche later filled by ornithischian and thus possibly supressed early ornithischian diversity through the Late Triassic.
REFERENCES
Dzik, J. 2003. A beaked herbivorous archosaur with dinosaur affinities from the early Late Triassic of Poland. Journal of Vertebrate Paleontology 23:556-574.
Dzik, J., and T. Sulej. 2007. A review of the Early Triassic Krasiejow biota from Silesia, Poland. Paleontologia Polonica 64:3-27.
Ezcurra, M. D. 2006. A review of the systematic position of the dinosauriform archosaur Eucoelophysis baldwini from the Upper Triassic of New Mexico, U.S.A. Geodiversitas 28:649-684.
Ferigolo, J. and M. Langer. 2007. A late Triassic dinosauriform from south Brazil and the origin of the ornithischian predentary bone. Historical Biology 19:23-33.
Irmis, R. B., Parker, W. G., and S. N. Nesbitt, 2005. Critical review of the Late Triassic dinosaur record, part 2: Ornithischia. Society of Vertebrate Paleontology 25(3):73A.
Irmis, R. B., Parker, W. G., Nesbitt, S. J., and J. Liu, 2007. Early ornithischian dinosaurs: the Triassic Record. Historical Biology 19:3-22.
Irmis, R. B., Nesbitt, S. J., Padian, K., Smith, N. D., Turner, A. H., Woody, D., and A. Downs. 2007. A Late Triassic dinosauromorph assemblage from New Mexico and the rise of dinosaurs. Science 317:358-361.
Nesbitt, S. N., Irmis, R. B., and W. G. Parker, 2005. Critical review of the Late Triassic dinosaur record, part 3: Saurischians of North America. Society of Vertebrate Paleontology 25(3):96A.
Nesbitt, S. J., Irmis, R. B., and W. G. Parker. 2007. A critical reevaluation of the Late Triassic dinosaur taxa of North America. Journal of Systematic Palaeontology 5:209-243.
Parker, W. G., Irmis, R. B., and S. J. Nesbitt. 2006. Review of the Late Triassic dinosaur record from Petrified Forest National Park, Arizona. Museum of Northern Arizona Bulletin 62:160-161.
New Paper on the Origin and Early Evolution of Dinosaurs
Langer, M.C., Ezcurra, M.D., Bittencourt, J.S., and F.E. Novas. 2009. The origin and early evolution of dinosaurs. Biological Reviews 84:1-56. doi:10.1111/j.1469-185X.2009.00094.x
ABSTRACT-The oldest unequivocal records of Dinosauria were unearthed from Late Triassic rocks(approximately 230 Ma)accumulated over extensional rift basins in southwestern Pangea. The better known of these are Herrerasaurus ischigualastensis, Pisanosaurus mertii, Eoraptor lunensis, and Panphagia protos from the Ischigualasto Formation, Argentina, and Staurikosaurus pricei and Saturnalia tupiniquim from the Santa Maria Formation, Brazil. No uncontroversial dinosaur body fossils are known from older strata, but the Middle Triassic origin of the lineage may be inferred from both the footprint record and its sister-group relation to Ladinian basal dinosauromorphs. These include the typical Marasuchus lilloensis, more basal forms such as Lagerpeton and Dromomeron, as well as silesaurids: a possibly monophyletic group composed of Mid-Late Triassic forms that may represent immediate sister taxa to dinosaurs. The first phylogenetic definition to fit the current understanding of Dinosauria as a node-based taxon solely composed of mutually exclusive Saurischia and Ornithischia was given as ‘‘all descendants of the most recent common ancestor of birds and Triceratops’’. Recent cladistic analyses of early dinosaurs agree that Pisanosaurus mertii is a basal ornithischian; that Herrerasaurus ischigualastensis and Staurikosaurus pricei belong in a monophyletic Herrerasauridae; that herrerasaurids, Eoraptor lunensis, and Guaibasaurus candelariensis are saurischians; that Saurischia includes two main groups, Sauropodomorpha and Theropoda; and that Saturnalia tupiniquim is a basal member of the sauropodomorph lineage. On the contrary, several aspects of basal dinosaur phylogeny remain controversial, including the position of herrerasaurids, E. lunensis, and G. candelariensis as basal theropods or basal saurischians, and the affinity and/or validity of more fragmentary taxa such as Agnosphitys cromhallensis, Alwalkeria maleriensis, Chindesaurus bryansmalli, Saltopus elginensis, and Spondylosoma absconditum. The identification of dinosaur apomorphies is jeopardized by the incompleteness of skeletal remains attributed to most basal dinosauromorphs, the skulls and forelimbs of which are particularly poorly known. Nonetheless, Dinosauria can be diagnosed by a suite of derived traits, most of which are related to the anatomy of the pelvic girdle and limb. Some of these are connected to the acquisition of a fully erect bipedal gait, which has been traditionally suggested to represent a key adaptation that allowed, or even promoted, dinosaur radiation during Late Triassic times. Yet, contrary to the classical ‘‘competitive’’ models, dinosaurs did not gradually replace other terrestrial tetrapods over the Late Triassic. In fact, the radiation of the group comprises at least three landmark moments, separated by controversial (Carnian Norian, Triassic-Jurassic) extinction events. These are mainly characterized by early diversification in Carnian times, a Norian increase in diversity and (especially) abundance, and the occupation of new niches from the Early Jurassic onwards. Dinosaurs arose from fully bipedal ancestors, the diet of which may have been carnivorous or omnivorous. Whereas the oldest dinosaurs were geographically restricted to south Pangea, including rare ornithischians and more abundant basal members of the saurischian lineage, the group achieved a nearly global distribution by the latest Triassic, especially with the radiation of saurischian groups such as ‘‘prosauropods’’ and coelophysoids.
ABSTRACT-The oldest unequivocal records of Dinosauria were unearthed from Late Triassic rocks(approximately 230 Ma)accumulated over extensional rift basins in southwestern Pangea. The better known of these are Herrerasaurus ischigualastensis, Pisanosaurus mertii, Eoraptor lunensis, and Panphagia protos from the Ischigualasto Formation, Argentina, and Staurikosaurus pricei and Saturnalia tupiniquim from the Santa Maria Formation, Brazil. No uncontroversial dinosaur body fossils are known from older strata, but the Middle Triassic origin of the lineage may be inferred from both the footprint record and its sister-group relation to Ladinian basal dinosauromorphs. These include the typical Marasuchus lilloensis, more basal forms such as Lagerpeton and Dromomeron, as well as silesaurids: a possibly monophyletic group composed of Mid-Late Triassic forms that may represent immediate sister taxa to dinosaurs. The first phylogenetic definition to fit the current understanding of Dinosauria as a node-based taxon solely composed of mutually exclusive Saurischia and Ornithischia was given as ‘‘all descendants of the most recent common ancestor of birds and Triceratops’’. Recent cladistic analyses of early dinosaurs agree that Pisanosaurus mertii is a basal ornithischian; that Herrerasaurus ischigualastensis and Staurikosaurus pricei belong in a monophyletic Herrerasauridae; that herrerasaurids, Eoraptor lunensis, and Guaibasaurus candelariensis are saurischians; that Saurischia includes two main groups, Sauropodomorpha and Theropoda; and that Saturnalia tupiniquim is a basal member of the sauropodomorph lineage. On the contrary, several aspects of basal dinosaur phylogeny remain controversial, including the position of herrerasaurids, E. lunensis, and G. candelariensis as basal theropods or basal saurischians, and the affinity and/or validity of more fragmentary taxa such as Agnosphitys cromhallensis, Alwalkeria maleriensis, Chindesaurus bryansmalli, Saltopus elginensis, and Spondylosoma absconditum. The identification of dinosaur apomorphies is jeopardized by the incompleteness of skeletal remains attributed to most basal dinosauromorphs, the skulls and forelimbs of which are particularly poorly known. Nonetheless, Dinosauria can be diagnosed by a suite of derived traits, most of which are related to the anatomy of the pelvic girdle and limb. Some of these are connected to the acquisition of a fully erect bipedal gait, which has been traditionally suggested to represent a key adaptation that allowed, or even promoted, dinosaur radiation during Late Triassic times. Yet, contrary to the classical ‘‘competitive’’ models, dinosaurs did not gradually replace other terrestrial tetrapods over the Late Triassic. In fact, the radiation of the group comprises at least three landmark moments, separated by controversial (Carnian Norian, Triassic-Jurassic) extinction events. These are mainly characterized by early diversification in Carnian times, a Norian increase in diversity and (especially) abundance, and the occupation of new niches from the Early Jurassic onwards. Dinosaurs arose from fully bipedal ancestors, the diet of which may have been carnivorous or omnivorous. Whereas the oldest dinosaurs were geographically restricted to south Pangea, including rare ornithischians and more abundant basal members of the saurischian lineage, the group achieved a nearly global distribution by the latest Triassic, especially with the radiation of saurischian groups such as ‘‘prosauropods’’ and coelophysoids.
More Free PDFs
Paläontologische Zeitschrift, now published by Springer, is offering open access for the month of November only.
http://www.springerlink.com/content/0031-0220?sa_campaign=email/PROM/PSE11800_V1
The New Mexico Museum of New Mexico and Science is also offering free PDFs of many of its published bulletins. Obviously there are lots of free Triassic PDFs here but the one that I highly recommend is Bulletin #4 (Long and Murry, 1995 - Late Triassic Carnian and Norian Tetrapods from the Southwestern United States). Although becoming dated it is still one of the quintessential references for anyone interested in Late Triassic vertebrates of the American southwest (and one of the most cited Triassic references ever). This has been out of print for awhile and those who have copies know that they were poorly bound and thus most existing copies are in tatters. Here is your chance to get the volume in its entirety.
http://econtent.unm.edu/cdm4/document.php?CISOROOT=/bulletins&CISOPTR=659&REC=6
BTW...you'll have to turn off your pop-up blocker to get the bulletin.
http://www.springerlink.com/content/0031-0220?sa_campaign=email/PROM/PSE11800_V1
The New Mexico Museum of New Mexico and Science is also offering free PDFs of many of its published bulletins. Obviously there are lots of free Triassic PDFs here but the one that I highly recommend is Bulletin #4 (Long and Murry, 1995 - Late Triassic Carnian and Norian Tetrapods from the Southwestern United States). Although becoming dated it is still one of the quintessential references for anyone interested in Late Triassic vertebrates of the American southwest (and one of the most cited Triassic references ever). This has been out of print for awhile and those who have copies know that they were poorly bound and thus most existing copies are in tatters. Here is your chance to get the volume in its entirety.
http://econtent.unm.edu/cdm4/document.php?CISOROOT=/bulletins&CISOPTR=659&REC=6
BTW...you'll have to turn off your pop-up blocker to get the bulletin.
Tyrannosauroid from the Bathonian (Middle Jurassic) of England
Important new Jurassic paper for those of you not subscribed to the VRTPALEO listserve...
RAUHUT, O.W.M., A.C. MILNER, and S. MOORE-FAY. 2009. Cranial osteology and phylogenetic position of the theropod dinosaur Proceratosaurus bradleyi(Woodward, 1910) from the Middle Jurassic of England. Zoological Journal of the Linnean Society Early View doi: 10.1111/j.1096-3642.2009.00591.x
ABSTRACT
The cranial osteology of the small theropod dinosaur Proceratosaurus from the Bathonian of Minchinhampton, England, is described in detail, based on new preparation and computed tomography (CT) scan images of the type, and only known, specimen. Proceratosaurus is an unusual theropod with markedly enlarged external nares and a cranial crest starting at the premaxillary-nasal junction. The skull is highly pneumatic, with pneumatized nasals, jugals, and maxillae, as well as a highly pneumatic braincase, featuring basisphenoid, anterior tympanic, basipterygoid, and carotid recesses. The dentition is unusual, with small premaxillary teeth and much larger lateral teeth, with a pronounced size difference of the serrations between the mesial and distal carina. The first dentary tooth is somewhat procumbent and flexed anteriorly. Phylogenetic analysis places Proceratosaurus in the Tyrannosauroidea, in a monophyletic clade Proceratosauridae, together with the Oxfordian Chinese taxon Guanlong. The Bathonian age of Proceratosaurus extends the origin of all clades of basal coelurosaurs back into the Middle Jurassic, and provides evidence for an early, Laurasia-wide, dispersal of the Tyrannosauroidea during the late Middle to Late Jurassic.
RAUHUT, O.W.M., A.C. MILNER, and S. MOORE-FAY. 2009. Cranial osteology and phylogenetic position of the theropod dinosaur Proceratosaurus bradleyi(Woodward, 1910) from the Middle Jurassic of England. Zoological Journal of the Linnean Society Early View doi: 10.1111/j.1096-3642.2009.00591.x
ABSTRACT
The cranial osteology of the small theropod dinosaur Proceratosaurus from the Bathonian of Minchinhampton, England, is described in detail, based on new preparation and computed tomography (CT) scan images of the type, and only known, specimen. Proceratosaurus is an unusual theropod with markedly enlarged external nares and a cranial crest starting at the premaxillary-nasal junction. The skull is highly pneumatic, with pneumatized nasals, jugals, and maxillae, as well as a highly pneumatic braincase, featuring basisphenoid, anterior tympanic, basipterygoid, and carotid recesses. The dentition is unusual, with small premaxillary teeth and much larger lateral teeth, with a pronounced size difference of the serrations between the mesial and distal carina. The first dentary tooth is somewhat procumbent and flexed anteriorly. Phylogenetic analysis places Proceratosaurus in the Tyrannosauroidea, in a monophyletic clade Proceratosauridae, together with the Oxfordian Chinese taxon Guanlong. The Bathonian age of Proceratosaurus extends the origin of all clades of basal coelurosaurs back into the Middle Jurassic, and provides evidence for an early, Laurasia-wide, dispersal of the Tyrannosauroidea during the late Middle to Late Jurassic.
Enigmatic Triassic Fossils - Agnosphitys cromhallensis
Alton Dooley over at Updates from the VPL has some excellent photos of the holotype material of Agnosphitys cromhallensis from the Upper Triassic fissure fills of England. The name, 'unknown begetter', reflects upon the unclear phylogentic relationships of this taxon. The original describers, Fraser et al. (2002), considered it to be a dinosauromorph more derived than Eoraptor and Herrerasaurus, but just outside of Dinosauria. It is known from an isolated left ilium, a left maxilla, a right humerus and a left astragalus. There is also a referred tooth. The association of this material was questioned with Langer (2004) considering it a nomen dubium.
The ilium possesses a distinct brevis shelf and 'open' ventral portion of the acetabulum (so it was slightly perforated), yet only has scars for two sacrals. The subrectangular deltopectoral crest on the humerus is typical for dinosauromorphs and the astragalus is very similar to that of basal saurischians (Nesbitt et al., 2007). Thus these specimens contain a melange of basal and derived characters making its phylogenetic placement uncertain (Fraser et al., 2002). This is also a very small animal as the humerus length is under 35mm. Unfortunately, more material needs to be found to elucidate the relationships of this animal, but what is present is not only very well preserved but extremely interesting.
REFERENCES
Fraser, N. C., Padian, K., Walkden, G. M., and Davis, A. L. M. 2002. Basal dinosauriform remains from Britain and the diagnosis of the Dinosauria. Palaeontology 45:79–95.
Langer, M.C. 2004. Basal Saurischia. In: Weishampel, D.B., Dodson, P., & Osmolska, H. (Eds.). The Dinosauria (2nd Edition). Berkeley: University of California Press. Pp. 25–46.
Nesbitt, S. J., Irmis, R. B. & Parker, W. G. 2007. A critical re-evaluation of the Late Triassic dinosaur taxa of North America. Journal of Systematic Palaeontology 5, 209-243.
The ilium possesses a distinct brevis shelf and 'open' ventral portion of the acetabulum (so it was slightly perforated), yet only has scars for two sacrals. The subrectangular deltopectoral crest on the humerus is typical for dinosauromorphs and the astragalus is very similar to that of basal saurischians (Nesbitt et al., 2007). Thus these specimens contain a melange of basal and derived characters making its phylogenetic placement uncertain (Fraser et al., 2002). This is also a very small animal as the humerus length is under 35mm. Unfortunately, more material needs to be found to elucidate the relationships of this animal, but what is present is not only very well preserved but extremely interesting.
REFERENCES
Fraser, N. C., Padian, K., Walkden, G. M., and Davis, A. L. M. 2002. Basal dinosauriform remains from Britain and the diagnosis of the Dinosauria. Palaeontology 45:79–95.
Langer, M.C. 2004. Basal Saurischia. In: Weishampel, D.B., Dodson, P., & Osmolska, H. (Eds.). The Dinosauria (2nd Edition). Berkeley: University of California Press. Pp. 25–46.
Nesbitt, S. J., Irmis, R. B. & Parker, W. G. 2007. A critical re-evaluation of the Late Triassic dinosaur taxa of North America. Journal of Systematic Palaeontology 5, 209-243.
Why I Use Pseudosuchia Instead of Crurotarsi for the Crocodile-line Archosaurs
This issue was briefly mentioned on the Vertebrate Paleontology List-server about a week ago and I feel like discussing this a bit further. A quick perusal of archosaurian literature will show that there is a dichotomy in the nomenclature when referring to the lineage of Archosauria that leads to the crocodylians. Some workers will refer to this clade as Pseudosuchia and others as Crurotarsi, with the latter seeming to be the most popular. However, I along with some of my closest Triassic collaborators prefer Pseudosuchia over Crurotarsi, and often when I review papers I will suggest that workers using Crurotarsi switch. Why? Well for me it comes down to two issues, priority and stability.
This problem has been reviewed by several workers, such as Brochu (1997) and most recently Senter (2005). Gauthier and Padian (1985) defined Pseudosuchia as "crocodiles and all archosaurs closer to crocodiles than to birds"; however, Pseudosuchia has a much longer history dating back to the late 1800s, and although it has always had the intent of containing non-dinosaurian archosaurs, the membership of this clade has changed through the years and at some points even included some of what are now considered to be non-dinosaurian ornithodirans (the bird-line clade).
Several authors disliked Gauthier and Padian's (1985) redefining of what they considered to be an "ill-defined and misused" name. Furthermore, the name is in a sense contradictory as Pseudosuchia means "false-crocodiles" yet includes crocodiles as members. Accordingly Benton and Clark (1988) suggested a new name, "Crocodylotarsi", and although they did not explicitly define this clade they inferred that it was the same as Pseudosuchia. Sereno and Arcucci (1990) proposed a third name, Crurotarsi, which Sereno (1991) defined as "Parasuchia, Ornithosuchidae, Prestosuchus, Suchia, and all decendents of their common ancestor".
However, just because a group once contained members that have since been recognized as belonging to other groups does not warrant abandonment. Indeed if this were the case very few names would be valid, including Dinosauria. Likewise, contradictory names also are not grounds for dismissal, for example the name phytosaur means 'plant-reptile' although they surely ate everything but. Despite this we are still stuck with the contradictory name. Furthermore, there is no confusion among modern workers as to the meaning of Pseudosuchia, so statements to the contrary are moot. When I say something is a pseudosuchian, those familiar with archosaurs clearly understand what I mean.
Crocodylotarsi has been used by some workers but has since fallen out of usage with most modern workers using either Pseudosuchia or Crurotarsi. As all three groups currently have the same membership it has been argued by some that Pseudosuchia should be used as it has precedence. I agree in principle that the first defined name should have priority and this is the reason that I use Pseudosuchia instead of Crocodylotarsi. However, as noted by Brochu (1997) and Senter (2005) the definitions of Pseudosuchia and Crurotarsi are not the same.
Pseudosuchia is stem-based and thus is flexible to future changes, as any archosaur that is not an ornithodiran is included in this group. Crurotarsi, however, is defined as a node-based taxon and thus has an explicit membership, most notably phytosaurs (parasuchians), ornithosuchids, Prestosuchus, aetosaurs, "rauisuchians", and crocodylomorphs. This definition is much less flexible. In fact let's just suppose that the basal most group of crurotarsans, the phytosaurs, fell outside of the crown-clade Archosauria, and were instead considered to be derived archosauriforms. What would happen to Pseudosuchia and Crurotarsi? The content of Pseudosuchia would be pretty much the same except that phytosaurs would no longer be constituents. In contrast, because the base of Crurotarsi is specified by phytosaurs, Crurotarsi would now include phytosaurs plus all of Archosauria. Thus dinosaurs (including birds) would be Crurotarsans by definition. As you can see this definition is much less stable, another reason why I prefer and highly recommend that all workers use Pseudosuchia over Crurotarsi. Admit it, having to say "non-phytosaurian and non-ornithiodiran crurotarsan" is pretty clunky!
Actually, if this ever did happen ;), in my eyes Crurotarsi might actually now be a useful name when discussing phytosaurs, as you could now simply say that phytosaurs are the basalmost crurotarsans and still be correct. This is probably just slightly more explicit than simply saying they are derived archosauriforms.
For much more detail on this issue read Brochu (1997) and Senter (2005). You can also check out this page for a different opinion.
REFERENCES
Benton, M.J., and J.M. Clark. 1988. Archosaur phylogeny and the relationships of the Crocodylia. Pp. 295–338 in M.J. Benton (ed.). The Phylogeny and Classifi cation of the Tetrapods, Volume 1: Amphibians, Reptiles, Birds. Clarendon Press, Oxford.
Brochu, C.J. 1997. Synonymy, Redundancy, and the name of the crocodile stem group. Journal of Vertebrate Paleontology 17:448-449.
Gauthier, J., and K. Padian. 1985. Phylogenetic, functional, and aerodynamic analyses of the origin of birds and their flight. Pp. 185–197 in M.K. Hecht, J.H. Ostrom, G. Viohl, and P.
Wellnhofer (eds.). The Beginnings of Birds. Freunde des Jura- Museums, Eichstätt.
Senter, P. 2005. Phylogenetic taxonomy and the names of the major archosaurian (Reptilia) clades. PaleoBios 25:1–7.
Sereno, P.C. 1991. Basal archosaurs: phylogenetic relationships and functional implications. Society of Vertebrate Paleontology Memoir 2:1–53.
Sereno, P.C., and A.B. Arcucci. 1990. The monophyly of crurotarsal archosaurs and the origin of bird and crocodile ankle joints. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen
180:21–52.
Phytosaur Taxonomy Flowchart
I remember sitting down one evening back in 2001 and putting this together. It proceeds through time from left to right. This is why nobody wants to research phytosaur taxonomy!
Rhaetian Magneto-biostratigraphy from the Southern Alps (Italy): Constraints on Triassic Chronology
This is fairly significant as it argues for quite a long Rhaetian Stage of the latest Triassic. If this is correct it means that a sizable portion of the upper part of the Chinle Formation could actually be Rhaetian in age. Not bad considering not too long ago workers were arguing if the Rhaetian was really even applicable outside of the marine realm.
Muttoni, G., Kent, D.V., Jadoul, F., Olsen, P.E., Rigo, M., Galli, M.T., and A. Nicora. 2009. Rhaetian magneto-biostratigraphy from the Southern Alps (Italy): Constraints on Triassic chronology. Palaeogeography, Palaeoclimatology, Palaeoecology. doi: 10.1016/j.palaeo.2009.10.014.
ABSTRACT: New Late Triassic-earliest Jurassic magneto-biostratigraphic data have been obtained from three overlapping sections in the Southern Alps, Italy (Costa Imagna, Brumano, Italcementi Quarry), comprised of ~ 520 m of shallow marine carbonates outcropping in stratigraphic continuity. Characteristic magnetic components of presumed depositional age record a sequence of 9 normal and reverse polarity magnetozones (as defined by at least three stratigraphically superposed samples) linked by conodont and palynofloral evidence from this study and the literature to Rhaetian to Triassic–Jurassic boundary age. This represents a significantly larger number of polarity zones than previously recognized in more condensed
Rhaetian sections from the literature, and by inference represents more time. These data are placed in a broader Late Triassic temporal framework by means of correlations to published magneto-biostratigraphic data from the Tethyan marine Pizzo Mondello section and the Newark astronomical polarity time scale (APTS). This framework is consistent with a position of the
Norian–Rhaetian boundary (as defined at Brumano and Pizzo Mondello by the first appearance of Misikella posthernsteini) within Newark magnetozones E17r–E19r in the ~ 207–210 Ma time interval, in basic agreement with the position originally estimated in the Newark using pollen biostratigraphy (E18 at 208–209 Ma). This framework is also consistent with the position of
the Triassic–Jurassic boundary interval (placed at Italcementi Quarry at the acme of Kraeuselisporites reissingeri coincident with a negative carbon isotope excursion) correlative to just above Newark magnetozone E23r and just below the oldest CAMP lavas dated at ~ 202 Ma. Hence, we estimate the duration of the Rhaetian to be ~ 5.5–8.5 Myr (or even longer if the
Triassic–Jurassic boundary is instead placed above the negative carbon isotope excursion as at Kuhjoch, which is the designated GSSP for the base of the Hettangian), and encompassing 9 magnetozones. This duration contrasts with a duration of ~ 2 Myr and only ~ 4 magnetozones in several alternative published magneto-biostratigraphic schemes.
Muttoni, G., Kent, D.V., Jadoul, F., Olsen, P.E., Rigo, M., Galli, M.T., and A. Nicora. 2009. Rhaetian magneto-biostratigraphy from the Southern Alps (Italy): Constraints on Triassic chronology. Palaeogeography, Palaeoclimatology, Palaeoecology. doi: 10.1016/j.palaeo.2009.10.014.
ABSTRACT: New Late Triassic-earliest Jurassic magneto-biostratigraphic data have been obtained from three overlapping sections in the Southern Alps, Italy (Costa Imagna, Brumano, Italcementi Quarry), comprised of ~ 520 m of shallow marine carbonates outcropping in stratigraphic continuity. Characteristic magnetic components of presumed depositional age record a sequence of 9 normal and reverse polarity magnetozones (as defined by at least three stratigraphically superposed samples) linked by conodont and palynofloral evidence from this study and the literature to Rhaetian to Triassic–Jurassic boundary age. This represents a significantly larger number of polarity zones than previously recognized in more condensed
Rhaetian sections from the literature, and by inference represents more time. These data are placed in a broader Late Triassic temporal framework by means of correlations to published magneto-biostratigraphic data from the Tethyan marine Pizzo Mondello section and the Newark astronomical polarity time scale (APTS). This framework is consistent with a position of the
Norian–Rhaetian boundary (as defined at Brumano and Pizzo Mondello by the first appearance of Misikella posthernsteini) within Newark magnetozones E17r–E19r in the ~ 207–210 Ma time interval, in basic agreement with the position originally estimated in the Newark using pollen biostratigraphy (E18 at 208–209 Ma). This framework is also consistent with the position of
the Triassic–Jurassic boundary interval (placed at Italcementi Quarry at the acme of Kraeuselisporites reissingeri coincident with a negative carbon isotope excursion) correlative to just above Newark magnetozone E23r and just below the oldest CAMP lavas dated at ~ 202 Ma. Hence, we estimate the duration of the Rhaetian to be ~ 5.5–8.5 Myr (or even longer if the
Triassic–Jurassic boundary is instead placed above the negative carbon isotope excursion as at Kuhjoch, which is the designated GSSP for the base of the Hettangian), and encompassing 9 magnetozones. This duration contrasts with a duration of ~ 2 Myr and only ~ 4 magnetozones in several alternative published magneto-biostratigraphic schemes.
Just In Case You Missed This One
This came out about three weeks ago in PLoS ONE. Pretty cool study showing how different types of dinosaurs would negotiate a particularily difficult terrain.
Wilson, J. A., Marsicano, C. A., and R. M. H. Smith. 2009. Dynamic Locomotor Capabilities Revealed by Early Dinosaur Trackmakers from Southern Africa. PLoS ONE 4(10): e7331. doi:10.1371/journal.pone.0007331.
ABSTRACT
Background
A new investigation of the sedimentology and ichnology of the Early Jurassic Moyeni tracksite in Lesotho, southern Africa has yielded new insights into the behavior and locomotor dynamics of early dinosaurs.
Methodology/Principal Findings
The tracksite is an ancient point bar preserving a heterogeneous substrate of varied consistency and inclination that includes a ripple-marked riverbed, a bar slope, and a stable algal-matted bar top surface. Several basal ornithischian dinosaurs and a single theropod dinosaur crossed its surface within days or perhaps weeks of one another, but responded to substrate heterogeneity differently. Whereas the theropod trackmaker accommodated sloping and slippery surfaces by gripping the substrate with its pedal claws, the basal ornithischian trackmakers adjusted to the terrain by changing between quadrupedal and bipedal stance, wide and narrow gauge limb support (abduction range = 31°), and plantigrade and digitigrade foot posture.
Conclusions/Significance
The locomotor adjustments coincide with changes in substrate consistency along the trackway and appear to reflect ‘real time’ responses to a complex terrain. It is proposed that these responses foreshadow important locomotor transformations characterizing the later evolution of the two main dinosaur lineages. Ornithischians, which shifted from bipedal to quadrupedal posture at least three times in their evolutionary history, are shown to have been capable of adopting both postures early in their evolutionary history. The substrate-gripping behavior demonstrated by the early theropod, in turn, is consistent with the hypothesized function of pedal claws in bird ancestors.
Wilson, J. A., Marsicano, C. A., and R. M. H. Smith. 2009. Dynamic Locomotor Capabilities Revealed by Early Dinosaur Trackmakers from Southern Africa. PLoS ONE 4(10): e7331. doi:10.1371/journal.pone.0007331.
ABSTRACT
Background
A new investigation of the sedimentology and ichnology of the Early Jurassic Moyeni tracksite in Lesotho, southern Africa has yielded new insights into the behavior and locomotor dynamics of early dinosaurs.
Methodology/Principal Findings
The tracksite is an ancient point bar preserving a heterogeneous substrate of varied consistency and inclination that includes a ripple-marked riverbed, a bar slope, and a stable algal-matted bar top surface. Several basal ornithischian dinosaurs and a single theropod dinosaur crossed its surface within days or perhaps weeks of one another, but responded to substrate heterogeneity differently. Whereas the theropod trackmaker accommodated sloping and slippery surfaces by gripping the substrate with its pedal claws, the basal ornithischian trackmakers adjusted to the terrain by changing between quadrupedal and bipedal stance, wide and narrow gauge limb support (abduction range = 31°), and plantigrade and digitigrade foot posture.
Conclusions/Significance
The locomotor adjustments coincide with changes in substrate consistency along the trackway and appear to reflect ‘real time’ responses to a complex terrain. It is proposed that these responses foreshadow important locomotor transformations characterizing the later evolution of the two main dinosaur lineages. Ornithischians, which shifted from bipedal to quadrupedal posture at least three times in their evolutionary history, are shown to have been capable of adopting both postures early in their evolutionary history. The substrate-gripping behavior demonstrated by the early theropod, in turn, is consistent with the hypothesized function of pedal claws in bird ancestors.
Proof! Dinosaurs and People Co-existed!
Now I've seen it with my own two eyes, a place where dinosaurs and humans co-habitate. Here is a close-up of part of the village.
Notice the crude stone construction and lack of straight lines and 90 degree angles.
Here is one of the dinosaurs, a large 'brontosaur' with some kind of transport device on its back. Actually the dinosaur is the transport device.
Here is one of the 'human' inhabitants. Notice the primitive feature of on three digit on the pes...and a seriously large snozolla.
Here is a human powered mechanical transport.
Some kind of primitive service station. Fossils using fossil fuels. Ironic!
Notice the crude stone construction and lack of straight lines and 90 degree angles.Here is one of the dinosaurs, a large 'brontosaur' with some kind of transport device on its back. Actually the dinosaur is the transport device.
Here is one of the 'human' inhabitants. Notice the primitive feature of on three digit on the pes...and a seriously large snozolla.
Here is a human powered mechanical transport.
Some kind of primitive service station. Fossils using fossil fuels. Ironic!Watch out for the active volcano (presumably Mesozoic) and the large pterosaur! I wonder what the pterosaurs eat here?
Ah Ha! Question answered. Better watch the kids in the open.
Or maybe this is more appropriate? What a menu. I can't believe the humans in this place eat dinosaur meat. What more proof do you need for their co-existance?
They have giant snakes too! This place is not the safest little town.
At least some slightly modern technology.
For those of you who have not seen one of these places, it is a Bedrock Village, one of two small little theme parks built in the U.S. in the 1960s and based on the TV show, The Flintstones. This one in in Valle, Arizona, about 25 miles south of the Grand Canyon. The is another in South Dakota. The one in Arizona is a bit hokey, but my kids really enjoyed it, especially climbing through the giant snake, which is actually a tunnel. The show was primetime TV in the early 1960s and reruns through my childhood, a staple of Saturday morning cartoons. I wonder if they are still on the air?
Ah Ha! Question answered. Better watch the kids in the open.Or maybe this is more appropriate? What a menu. I can't believe the humans in this place eat dinosaur meat. What more proof do you need for their co-existance?
They have giant snakes too! This place is not the safest little town.At least some slightly modern technology.
For those of you who have not seen one of these places, it is a Bedrock Village, one of two small little theme parks built in the U.S. in the 1960s and based on the TV show, The Flintstones. This one in in Valle, Arizona, about 25 miles south of the Grand Canyon. The is another in South Dakota. The one in Arizona is a bit hokey, but my kids really enjoyed it, especially climbing through the giant snake, which is actually a tunnel. The show was primetime TV in the early 1960s and reruns through my childhood, a staple of Saturday morning cartoons. I wonder if they are still on the air?
I remember hearing somewhere that The Flintstones represent a large percentage Americans' only experience with 'prehistoric life' and of course it shows co-habitation of humans and dinosaurs mixed with 'stone age' versions of modern technology, which many bought into. They should have put a disclaimer at the end of each show that it is pure fiction and does not depict accurate events in life history.
End of Blogpost Disclaimer: If you have gotten this far and still believe that dinosaurs and humans did indeed co-exist you need to do yourself a big favor. Go down to your local Community College and take a Historical Geology class (and read this post). Please do pay attention, you won't regret it. Yabba-Dabba-Doo.
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