Most analyses of taxonomic diversity and morphological disparity in the fossil record use a taxic approach, in which the researcher simply counts numbers of known taxa and uses these data for comparison. However, because the fossil record is spotty how can we be sure that these data are not affected by collecting biases? Phylogentic analyses provide a useful tool, because they project 'ghost lineages' depicting where these missing data may occur. Brusatte et al. (2008) looked at taxonomic diversity vs. morphological disparity in Triassic archosaurs using a taxic methodology. In that study they found that diversity and rates of morphological change were decoupled in regards to comparisons between Triassic pseudosuchians and ornithodirans.
In this paper Brusatte et al. provide a methodology for correcting the data phylogenetically, which for the most part consists of determining the character states for nodes within the MPTs and then adding these 'ancestors' to the diversity vs. disparity analysis. They look at several case studies and find for the Triassic archosaur study generally the same overall results as Brusatte et al. (2008).
Brusatte, S. L., Montanari, S., Yi, H.-y., and M. A. Norell. 2011. Phylogenetic corrections for morphological disparity analysis: new methodology and case studies. Paleobiology 37:1-22. DOI: 10.1666/09057.1Abstract - Taxonomic diversity and morphological disparity are different measures of biodiversity that together can describe large-scale evolutionary patterns. Diversity measures are often corrected by extending lineages back in time or adding additional taxa necessitated by a phylogeny, but disparity analyses focus on observed taxa only. This is problematic because some morphologies required by phylogeny are not included, some of which may help fill poorly sampled time bins. Moreover the taxic nature of disparity analyses makes it difficult to compare disparity measures with phylogenetically corrected diversity or morphological evolutionary rate curves. We present a general method for using phylogeny to correct measures of disparity, by including reconstructed ancestors in the disparity analysis. We apply this method to discrete character data sets focusing on Triassic archosaurs, Cenozoic carnivoramorph mammals, and Cretaceous–Cenozoic euarchontogliran mammals. Phylogenetic corrections do not simply mirror the taxic disparity patterns, but affect the three analyses in heterogeneous ways. Adding reconstructed ancestors can inflate morphospace, and the amount and direction of expansion differs depending on the taxonomic group in question. In some cases phylogenetic corrections give a temporal disparity curve indistinguishable from the taxic trend, but in other cases disparity is elevated in earlier time intervals relative to later bins, due to the extension of unsampled morphologies further back in time. The phylogenetic disparity curve for archosaurs differs little from the taxic curve, supporting a previously documented pattern of decoupled disparity and rates of morphological change in dinosaurs and their early contemporaries. Although phylogenetic corrections should not be used blindly, they are helpful when studying clades with major unsampled gaps in their fossil records.
REFERENCE
Brusatte, S.L., Benton, M.J., Ruta, M., and G.T. Lloyd. 2008. Superiority, competition, and opportunism in the evolutionary radiation of dinosaurs. Science 321:1485-1488.
Leonerasaurus taquetrensis, a New Derived Sauropodomorph from the Early Jurassic (or Late Triassic?) of Argentina
I'm not even going to attempt to delve into this new paper here because Adam Yates is back and has the detailed write-up at Dracovenator!
All of these recent sauropodomorph finds have me totally fired up to find one in the Chinle Formation this summer! (but I'll settle for the skull of Chindesaurus).
Pol, D., Garrido, A., and I. A. Cerda. 2011. A New Sauropodomorph Dinosaur from the Early Jurassic of Patagonia and the Origin and Evolution of the Sauropod-type Sacrum. PLoS ONE 6(1): e14572. doi:10.1371/journal.pone.0014572
ABSTRACT
Background
The origin of sauropod dinosaurs is one of the major landmarks of dinosaur evolution but is still poorly understood. This drastic transformation involved major skeletal modifications, including a shift from the small and gracile condition of primitive sauropodomorphs to the gigantic and quadrupedal condition of sauropods. Recent findings in the Late Triassic–Early Jurassic of Gondwana provide critical evidence to understand the origin and early evolution of sauropods.
Methodology/Principal Findings
A new sauropodomorph dinosaur, Leonerasaurus taquetrensis gen. et sp. nov., is described from the Las Leoneras Formation of Central Patagonia (Argentina). The new taxon is diagnosed by the presence of anterior unserrated teeth with a low spoon-shaped crown, amphicoelous and acamerate vertebral centra, four sacral vertebrae, and humeral deltopectoral crest low and medially deflected along its distal half. The phylogenetic analysis depicts Leonerasaurus as one of the closest outgroups of Sauropoda, being the sister taxon of a clade of large bodied taxa composed of Melanorosaurus and Sauropoda.
Conclusions/Significance
The dental and postcranial anatomy of Leonerasaurus supports its close affinities with basal sauropods. Despite the small size and plesiomorphic skeletal anatomy of Leonerasaurus, the four vertebrae that compose its sacrum resemble that of the large-bodied primitive sauropods. This shows that the appearance of the sauropod-type of sacrum predated the marked increase in body size that characterizes the origins of sauropods, rejecting a causal explanation and evolutionary linkage between this sacral configuration and body size. Alternative phylogenetic placements of Leonerasaurus as a basal anchisaurian imply a convergent acquisition of the sauropod-type sacrum in the new small-bodied taxon, also rejecting an evolutionary dependence of sacral configuration and body size in sauropodomorphs. This and other recent discoveries are showing that the characteristic sauropod body plan evolved gradually, with a step-wise pattern of character appearance.
All of these recent sauropodomorph finds have me totally fired up to find one in the Chinle Formation this summer! (but I'll settle for the skull of Chindesaurus).
Pol, D., Garrido, A., and I. A. Cerda. 2011. A New Sauropodomorph Dinosaur from the Early Jurassic of Patagonia and the Origin and Evolution of the Sauropod-type Sacrum. PLoS ONE 6(1): e14572. doi:10.1371/journal.pone.0014572
ABSTRACT
Background
The origin of sauropod dinosaurs is one of the major landmarks of dinosaur evolution but is still poorly understood. This drastic transformation involved major skeletal modifications, including a shift from the small and gracile condition of primitive sauropodomorphs to the gigantic and quadrupedal condition of sauropods. Recent findings in the Late Triassic–Early Jurassic of Gondwana provide critical evidence to understand the origin and early evolution of sauropods.
Methodology/Principal Findings
A new sauropodomorph dinosaur, Leonerasaurus taquetrensis gen. et sp. nov., is described from the Las Leoneras Formation of Central Patagonia (Argentina). The new taxon is diagnosed by the presence of anterior unserrated teeth with a low spoon-shaped crown, amphicoelous and acamerate vertebral centra, four sacral vertebrae, and humeral deltopectoral crest low and medially deflected along its distal half. The phylogenetic analysis depicts Leonerasaurus as one of the closest outgroups of Sauropoda, being the sister taxon of a clade of large bodied taxa composed of Melanorosaurus and Sauropoda.
Conclusions/Significance
The dental and postcranial anatomy of Leonerasaurus supports its close affinities with basal sauropods. Despite the small size and plesiomorphic skeletal anatomy of Leonerasaurus, the four vertebrae that compose its sacrum resemble that of the large-bodied primitive sauropods. This shows that the appearance of the sauropod-type of sacrum predated the marked increase in body size that characterizes the origins of sauropods, rejecting a causal explanation and evolutionary linkage between this sacral configuration and body size. Alternative phylogenetic placements of Leonerasaurus as a basal anchisaurian imply a convergent acquisition of the sauropod-type sacrum in the new small-bodied taxon, also rejecting an evolutionary dependence of sacral configuration and body size in sauropodomorphs. This and other recent discoveries are showing that the characteristic sauropod body plan evolved gradually, with a step-wise pattern of character appearance.
Coal Combustion as a Contributor to the End-Permian Extinction
A break from one fingered dinosaurs and the speculations of use for such a limb. This is a new article regarding a possible contributor to end-Permian marine extinctions. A popular news article is here.
Grasby, S. E., Sanei, H. and B. Beauchamp. 2011. Catastrophic dispersion of coal fly ash into oceans during the latest Permian extinction. Nature Geoscience. Published online 23 January 2011 http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1069.html
Abstract - During the latest Permian extinction about 250 Myr ago, more than 90% of marine species went extinct, and biogeochemical cycles were disrupted globally. The cause of the disruption is unclear, but a link between the eruption of the Siberian Trap flood basalts and the extinction has been suggested on the basis of the rough coincidence of the two events. The flood basalt volcanism released CO2. In addition, related thermal metamorphism of Siberian coal measures and organic-rich shales led to the emission of methane, which would have affected global climate and carbon cycling, according to model simulations. This scenario is supported by evidence for volcanic eruptions and gas release in the Siberian Tunguska Basin, but direct indicators of coal combustion have not been detected. Here we present analyses of terrestrial carbon in marine sediments that suggest a substantial amount of char was deposited in Permian aged rocks from the Canadian High Arctic immediately before the mass extinction. Based on the geochemistry and petrology of the char, we propose that the char was derived from the combustion of Siberian coal and organic-rich sediments by flood basalts, which was then dispersed globally. The char is remarkably similar to modern coal fly ash, which can create toxic aquatic conditions when released as slurries. We therefore speculate that the global distribution of ash could have created toxic marine conditions.
Grasby, S. E., Sanei, H. and B. Beauchamp. 2011. Catastrophic dispersion of coal fly ash into oceans during the latest Permian extinction. Nature Geoscience. Published online 23 January 2011 http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1069.html
Abstract - During the latest Permian extinction about 250 Myr ago, more than 90% of marine species went extinct, and biogeochemical cycles were disrupted globally. The cause of the disruption is unclear, but a link between the eruption of the Siberian Trap flood basalts and the extinction has been suggested on the basis of the rough coincidence of the two events. The flood basalt volcanism released CO2. In addition, related thermal metamorphism of Siberian coal measures and organic-rich shales led to the emission of methane, which would have affected global climate and carbon cycling, according to model simulations. This scenario is supported by evidence for volcanic eruptions and gas release in the Siberian Tunguska Basin, but direct indicators of coal combustion have not been detected. Here we present analyses of terrestrial carbon in marine sediments that suggest a substantial amount of char was deposited in Permian aged rocks from the Canadian High Arctic immediately before the mass extinction. Based on the geochemistry and petrology of the char, we propose that the char was derived from the combustion of Siberian coal and organic-rich sediments by flood basalts, which was then dispersed globally. The char is remarkably similar to modern coal fly ash, which can create toxic aquatic conditions when released as slurries. We therefore speculate that the global distribution of ash could have created toxic marine conditions.
More Evidence for Long Norian and Rhaetian Stages
Carnian-Norian boundary: ~226.6 Ma;
Lacian-Alaunian boundary: ~216.4 Ma (fairly equivalent to the old Carnian/Norian boundary);
Alaunian-Sevatian 1 boundary: 211.8 Ma;
Norian Rhaetian boundary: ~209.8 Ma.
Thus according to these data the early Norian is approximately 10 million years long, the middle Norian is 4.5 million years old, and the late Norian is 2 million years old for an approximately 17 million year long Norian stage. The Rhaetian is approximately 9 million years long.
Proposed biostratigraphic data from palynomorphs and conchostracans suggesting a shorter Norian are refuted.
Hüsing, S. K.,
Abstract - The Global Stratotype Section and Point (GSSP) for the Rhaetian Stage has recently been proposed at Steinbergkogel in Austria. We re-sampled the Steinbergkogel sections (STK-A and STK-B + C) in high-resolution to establish a robust magnetostratigraphy that allows global correlation. The palaeomagnetic signal at Steinbergkogel is composed of three components, which can be separated by thermal demagnetization. The highest temperature component, revealed between 280/300 and maximum 600 °C is of dual polarity and is interpreted as primary. Rock magnetic experiments showed that the signal is carried by magnetite. Our results allow correlation between the two individual Steinbergkogel outcrops. Subsequently, we correlate the two key biostratigraphic horizons for the base of the Rhaetian, the FO of M. hernsteini and the FAD of M. posthernsteini to other sections of the Tethys domain. The correlation to the astronomically dated continental successions of the Newark basin indicates that these positions for the base of the Rhaetian are most likely determined in chrons E16n and E16r, respectively. This correlation is confirmed by cyclostratigraphic control on the marine Pizzo Mondello (Italy) section, where a combination of long period Milankovitch cycles (~ 175-Myr) and short-eccentricity cycles (~ 100-kyr) provide additional correlation constraints, respectively supporting a long duration of the Rhaetian. Our study implies that the Norian and Rhaetian Stages have durations of ~ 17 and ~ 9 Myr.
REFERENCES
Muttoni, G., Kent, D.V., Jadoul, F., Olsen, P.E., Rigo, M., Galli, M.T., and A. Nicora. 2010. Rhaetian magneto-biostratigraphy from the Southern Alps (Italy): constraints on Triassic chronology. Palaeogeography, Palaeoclimatology, Palaeoecology 285: 1–16.
Muttoni, G., Kent, D.V., Olsen, P.E., Di Stefano, P., Lowrie, W., Bernasconi, S.M., and F. M. Hernandez. 2004. Tethyan magnetostratigraphy from Pizzo Mondello (Sicily)and correlation to the Late Triassic Newark astrochronological polarity time scale. Geological Society of America Bulletin 116: 1043–1058.
Agathoxylon, the Wood Morphogenus Previously Known as Araucarioxylon
We've known for a couple of years now that the name Araucarioxylon, used for the majority of the petrified wood from the Chinle Formation is illigitimate. Savidge (2007) reexamined the type specimens of Araucarioxylon arizonicum, and assigned it to a new genus, Pullisilvaxylon arizonicum. Problematic is that the type specimen is from the Black Forest Bed, which is much younger than the main log bearing horizon in Petrified Forest National Park where thousands of colorful logs have been referred to A. arizonicum for over a century.
Complicating this problem is that the majority of this wood has been almost completely agatized, obliterating the cellular structures used to make taxonomic assignments. Furthermore, Savidge (2007) found that there are actually several wood taxa at this horizon, in fact almost every specimen sampled turns out to be new. Thus, park staff are at a loss when asked what the name the main type of fossil wood in the park is, and most just simply still continue to use the invalid name Araucarioxylon.
Philippe, in this new paper, suggests that a better name for the morphogenus is Agathoxylon. However, I would be hesitant to refer the large amounts of currently unnamed wood to this genus as he also suggests that eventually it should be restricted to a single species. Furthermore, because of the restriction of the type of P. arizonicum, the majority of Chinle wood lacks a direct assignment to a species-group name. This is a mess that probably will never be resolved because of the poor preservation of the wood structures, thus the majority of Chinle wood will simply be referrable to Araucariaceae indeterminate (or maybe even a more inclusive clade or rank?).
Philippe, M., in press. How many species of Araucarioxylon? C. R. Palevol (2011), doi:10.1016/j.crpv.2010.10.010
Abstract - Fossil wood, similar to that of modern Araucariaceae, has been known for a long time, and is usually called Araucarioxylon. More than 400 morphospecies have been described, whereas this wood type displays few characteristic features. This taxonomical profusion is compounded by nomenclatural problems, Araucarioxylon being an illegitimate name. The status of the wood morphogenus, the infrageneric structure and the names that apply to the taxa designated for fossil woods of the Araucarioxylon-type are discussed. A database with 428 morphospecies designated for Araucarioxylon-type of wood is analyzed. The name Agathoxylon Hartig seems to be the most appropriate for the corresponding morphogenus. Albeit theoretically several hundred morphospecies could be recognized within this group, it is at least as probable that only one should be retained.
REFERENCES
Savidge, R.A. 2006. Xylotomic evidence for two new conifers and a ginkgo within the Late Triassic Chinle Formation of Petrified Forest National Park, Arizona, USA, 147–149. In Parker, W.G., Ash, S.R. & Irmis, R.B. (eds) A century of research at Petrified Forest National Park: geology and paleontology. Museum of Northern Arizona Bulletin 62.
Savidge, R. A. 2007. Wood anatomy of Late Triassic trees in Petrified Forest National Park, Arizona, USA, in relation to Araucarioxylon arizonicum Knowlton, 1889. Bulletin of Geosciences 82:301–328.
Savidge, R.A. & Ash, S.R. 2006. Arboramosa semicircumtrachea, an unusual Late Triassic tree in Petrified Forest National Park, Arizona, USA, 65–81. In Parker, W.G., Ash, S.R. & Irmis, R.B. (eds) A century of research at Petrified Forest National Park: geology and paleontology. Museum of Northern Arizona Bulletin 62.
Complicating this problem is that the majority of this wood has been almost completely agatized, obliterating the cellular structures used to make taxonomic assignments. Furthermore, Savidge (2007) found that there are actually several wood taxa at this horizon, in fact almost every specimen sampled turns out to be new. Thus, park staff are at a loss when asked what the name the main type of fossil wood in the park is, and most just simply still continue to use the invalid name Araucarioxylon.
Philippe, in this new paper, suggests that a better name for the morphogenus is Agathoxylon. However, I would be hesitant to refer the large amounts of currently unnamed wood to this genus as he also suggests that eventually it should be restricted to a single species. Furthermore, because of the restriction of the type of P. arizonicum, the majority of Chinle wood lacks a direct assignment to a species-group name. This is a mess that probably will never be resolved because of the poor preservation of the wood structures, thus the majority of Chinle wood will simply be referrable to Araucariaceae indeterminate (or maybe even a more inclusive clade or rank?).
Philippe, M., in press. How many species of Araucarioxylon? C. R. Palevol (2011), doi:10.1016/j.crpv.2010.10.010
Abstract - Fossil wood, similar to that of modern Araucariaceae, has been known for a long time, and is usually called Araucarioxylon. More than 400 morphospecies have been described, whereas this wood type displays few characteristic features. This taxonomical profusion is compounded by nomenclatural problems, Araucarioxylon being an illegitimate name. The status of the wood morphogenus, the infrageneric structure and the names that apply to the taxa designated for fossil woods of the Araucarioxylon-type are discussed. A database with 428 morphospecies designated for Araucarioxylon-type of wood is analyzed. The name Agathoxylon Hartig seems to be the most appropriate for the corresponding morphogenus. Albeit theoretically several hundred morphospecies could be recognized within this group, it is at least as probable that only one should be retained.
REFERENCES
Savidge, R.A. 2006. Xylotomic evidence for two new conifers and a ginkgo within the Late Triassic Chinle Formation of Petrified Forest National Park, Arizona, USA, 147–149. In Parker, W.G., Ash, S.R. & Irmis, R.B. (eds) A century of research at Petrified Forest National Park: geology and paleontology. Museum of Northern Arizona Bulletin 62.
Savidge, R. A. 2007. Wood anatomy of Late Triassic trees in Petrified Forest National Park, Arizona, USA, in relation to Araucarioxylon arizonicum Knowlton, 1889. Bulletin of Geosciences 82:301–328.
Savidge, R.A. & Ash, S.R. 2006. Arboramosa semicircumtrachea, an unusual Late Triassic tree in Petrified Forest National Park, Arizona, USA, 65–81. In Parker, W.G., Ash, S.R. & Irmis, R.B. (eds) A century of research at Petrified Forest National Park: geology and paleontology. Museum of Northern Arizona Bulletin 62.
Paleobiological Implications of Basal Ichthyosaur from Histological Data
Kolb, C., Sánchez-Villagra, M. R., and T. M. Scheyer. 2011. The palaeohistology of the basal ichthyosaur Mixosaurus Baur, 1887 (Ichthyopterygia, Mixosauridae) from the Middle Triassic: Palaeobiological implications. Comptes Rendus Palevol doi:10.1016/j.crpv.2010.10.008
Abstract - Here, we provide the first bone histological examination of an ontogenetic series of the basal ichthyosaur Mixosaurus encompassing postnatal to large adult specimens. Growth marks are present in sampled humeri, a femur, a fibula, as well as in other skeletal elements (gastral ribs). Ontogenetic changes are traceable throughout stylo- and zeugopodial development, but interior remodelling and resorption deleted part of the internal growth record in the primary cortex. Mixosaurus humeri started as flat structures consisting of a core of endochondral woven bone and residual calcified cartilage, whereas growth continued by deposition of periosteal fibrolamellar and parallel-fibred bone. Unlike the fast-growing post-Triassic ichthyosaurs that lack growth marks, microstructural and life history data are now becoming available for a basal ichthyosaur. The high growth rate of Mixosaurus may indicate that higher metabolic rates characterised small, non-thunniform ichthyosaurs, as had been suggested already for post-Triassic, cruising forms.
Abstract - Here, we provide the first bone histological examination of an ontogenetic series of the basal ichthyosaur Mixosaurus encompassing postnatal to large adult specimens. Growth marks are present in sampled humeri, a femur, a fibula, as well as in other skeletal elements (gastral ribs). Ontogenetic changes are traceable throughout stylo- and zeugopodial development, but interior remodelling and resorption deleted part of the internal growth record in the primary cortex. Mixosaurus humeri started as flat structures consisting of a core of endochondral woven bone and residual calcified cartilage, whereas growth continued by deposition of periosteal fibrolamellar and parallel-fibred bone. Unlike the fast-growing post-Triassic ichthyosaurs that lack growth marks, microstructural and life history data are now becoming available for a basal ichthyosaur. The high growth rate of Mixosaurus may indicate that higher metabolic rates characterised small, non-thunniform ichthyosaurs, as had been suggested already for post-Triassic, cruising forms.
Direct U-Pb Dating of Fossil Bone Material and Does the Presence of Paleocene Dinosaurs Even Matter?
Interesting paper, the focus of which is twofold: 1) demonstate the applicability of new U-Pb dating technology on fossil bone material; and 2) support the hypothesis that some non-avian dinosaurs survived into the earliest Paleocene. I'll need someone with more background on radioisotopic dating techniques to evaluate this paper for me, especially regarding aspects of Pb loss, diagenetic recrystallization, etc., but the implications are exciting if indeed this technique can be used to directly date fossil materials.
I think the idea of Paleocene dinosaurs will be debated for a long time, but really what does it matter? It is not as if non-avian dinosaurs made it into the Paleocene, that they made it very far in. Our base geologic timescales are based upon stratigraphic ranges of marine organisms, which are only now starting to be well calibrated. Correlation of these intervals between the marine and terrestrial realms is tricky at best and I would not be surprised if as we get more precision and accuracy in our dating techniques we find that there is a little slop around boundary defining events (i.e. extinctions of major terrestrial groups) and the exact dates defining the marine-defined boundaries.
But does it really matter if the last non-avian dinosaurs died out entirely by the exact last day of the Cretaceous, or if a few locally squeezed into the earliest Paleocene? These dates are so similar in relation to the overall earth timescale that they are pretty much simultaneous and really have no bearing on our ideas regarding the extinction of non-avian dinosaur. Same goes for the Triassic, if we find a phytosaur in the very earliest Jurassic strata is this really significant other than for general bean counting? I for one would not be surprised one bit if such a specimen was found; however, these data would not offer much in resolving the real question, which is why these major extinctions occurred in the first place.
Fassett, J.E., Heaman, L.M., and A. Simonetti. 2011. Direct U-Pb dating of Cretaceous and Paleocene dinosaur bones, San Juan Basin, New Mexico. Geology 39:159-162. doi: 10.1130/G31466.1
Abstract - Vertebrate fossils have been important for relative dating of terrestrial rocks for decades, but direct dating of these fossils has heretofore been unsuccessful. In this study we employ recent advances in laser ablation in situ U-Pb dating techniques to directly date two dinosaur fossils from the San Juan Basin of northwestern New Mexico and southwestern Colorado, United States. A Cretaceous dinosaur bone collected from just below the Cretaceous-Paleogene interface yielded a U-Pb date of 73.6 ± 0.9 Ma, in excellent agreement with a previously determined 40Ar/39Ar date of 73.04 ± 0.25 Ma for an ash bed near this site. The second dinosaur bone sample from Paleocene strata just above the Cretaceous-Paleogene interface yielded a Paleocene U-Pb date of 64.8 ± 0.9 Ma, consistent with palynologic, paleomagnetic, and fossil-mammal biochronologic data. This first successful direct dating of fossil vertebrate bone provides a new methodology with the potential to directly obtain accurate dates for any vertebrate fossil.
I think the idea of Paleocene dinosaurs will be debated for a long time, but really what does it matter? It is not as if non-avian dinosaurs made it into the Paleocene, that they made it very far in. Our base geologic timescales are based upon stratigraphic ranges of marine organisms, which are only now starting to be well calibrated. Correlation of these intervals between the marine and terrestrial realms is tricky at best and I would not be surprised if as we get more precision and accuracy in our dating techniques we find that there is a little slop around boundary defining events (i.e. extinctions of major terrestrial groups) and the exact dates defining the marine-defined boundaries.
But does it really matter if the last non-avian dinosaurs died out entirely by the exact last day of the Cretaceous, or if a few locally squeezed into the earliest Paleocene? These dates are so similar in relation to the overall earth timescale that they are pretty much simultaneous and really have no bearing on our ideas regarding the extinction of non-avian dinosaur. Same goes for the Triassic, if we find a phytosaur in the very earliest Jurassic strata is this really significant other than for general bean counting? I for one would not be surprised one bit if such a specimen was found; however, these data would not offer much in resolving the real question, which is why these major extinctions occurred in the first place.
Fassett, J.E., Heaman, L.M., and A. Simonetti. 2011. Direct U-Pb dating of Cretaceous and Paleocene dinosaur bones, San Juan Basin, New Mexico. Geology 39:159-162. doi: 10.1130/G31466.1
Abstract - Vertebrate fossils have been important for relative dating of terrestrial rocks for decades, but direct dating of these fossils has heretofore been unsuccessful. In this study we employ recent advances in laser ablation in situ U-Pb dating techniques to directly date two dinosaur fossils from the San Juan Basin of northwestern New Mexico and southwestern Colorado, United States. A Cretaceous dinosaur bone collected from just below the Cretaceous-Paleogene interface yielded a U-Pb date of 73.6 ± 0.9 Ma, in excellent agreement with a previously determined 40Ar/39Ar date of 73.04 ± 0.25 Ma for an ash bed near this site. The second dinosaur bone sample from Paleocene strata just above the Cretaceous-Paleogene interface yielded a Paleocene U-Pb date of 64.8 ± 0.9 Ma, consistent with palynologic, paleomagnetic, and fossil-mammal biochronologic data. This first successful direct dating of fossil vertebrate bone provides a new methodology with the potential to directly obtain accurate dates for any vertebrate fossil.
Eoraptor is a Sauropodomorph, and a New Basal Dinosaur, Eodromaeus murphi, from the Late Triassic of Argentina
The last decade has seen a renaissance in the study of basal dinosaurs and as a result of the resurgence in study we have seen a bunch of new dinosaur taxa coming from the Upper Triassic of North and South America (see excellent syntheses by Langer et al. 2010, and Brusatte et al., 2010). These include the stem-sauropodomorphs Saturnalia, Panphagia, and most recently Chromigosaurus (Langer, 2003; Martinez and Alcober, 2009; Ezcurra, 2010). Other new early dinosaurs include the herrerasaurid Sanjuansaurus, and the basal theropod Tawa (Nesbitt et al. 2010; Alcober and Martinez, 2010). We have also seen updated description and discussion of older taxa such as Chindesaurus and Pisanosaurus as well as the discovery and reinvestigation of numerous dinosauromorphs (e.g., Dzik, 2003; Ferigolo and Langer, 2007; Irmis et al., 2007a, b; Nesbitt et al., 2007, 2009, 2010). Furthermore, a plethora of phylogentic studies are attempting to work out the relationships of all of these taxa (e.g., Langer, 2004; Langer and Benton, 2006; Ezcurra, 2006, 2010; Irmis et al., 2007; Upchurch et al., 2007; Yates, 2007; Martinez and Alcobar, 2009; Nesbitt et al., 2009).
One point of contention in all of these analyses is the phylogenetic position of Eoraptor lunensis from the Upper Triassic Ischigualasto Formation. Originally considered the basal most theropod (e.g., Sereno et al. 1993), recent analysis have supported this hypothesis (Ezcurra, 2006, 2010; Nesbitt et al., 2009) or cast it as a basal saurischian outside of Eusaurischia (e.g., Langer, 2004; Langer and Benton, 2004; Upchurch et al., 2007; Yates, 2007; Martinez and Alcober, 2009).
A new paper out today in Science by Martinez et al. describes a new basal theropod taxon, Eodromaeus murphi, from the Ischigualasto Formation. This new taxon is known by much of the skeleton and represents the new theropod previously mentioned by Martinez et al. (2008). A phylogenetic analysis places Eodromaeus within Theropoda as the sister taxon to Neotheropoda (a position previously held by Tawa, which in this new analysis is a neotheropod) and the sister taxon to the herrerasaurid theropods.
Very striking in this analysis is the recovery of Eoraptor lunensis not only as a Eusaurischian but as a stem-sauropodomorph in a polytomy with Panphagia and Saturnalia (thus it would be a saturnaliine according to Ezcurra 2010; Guaibasaurus and Chromogisaurus were not included in the analysis). This positioning for Eoraptor had previously been alluded to by Martinez and Alcobar (2009), but this is the first time it has been supported by a phylogenetic analysis.
I'm sure this new analysis will cause quite a debate among basal dinosaur workers, especially regarding the ideas of taxon sampling and character inclusion/codings in phylogenetic analyses. The analysis by Martinez et al. excludes lots of incomplete/poorly known taxa as well as taxa that these authors percieve as being too far out phylogentically to have consequence to the question of basal dinosaur relationships. The character matrix is an updated version of Sereno (1999) and does not utilize many characters found in other studies such as Langer and Benton (2006), Ezcurra (2006), and Nesbitt et al. (2009). I don't really have a horse in this race given that I don't have a basal dinosaur analysis that I am personally working on, but as someone outside looking in, it is really difficult to compare across these various analyses given the strong differences in datasets being utilized. Hopefully we will see a consensus at some point.
Nonetheless, if Eoraptor is indeed found to be a basal sauropodomorph, this is of great interest because it gets us a step closer to seeing what the common ancestor of theropods and sauropodomorphs may have looked like.
Some other neat tidbits and conclusions from the paper:
-Like Eoraptor, Eodromaeous possesses a small row of teeth on the palatal ramus of the pterygoid.
-A new radioisotopic date for the top of the Ischigualasto Formation constrains the majority of the formation between 231.4 Ma and 225.9Ma, thus the Ischigualasto Formation spans the Carnian/Norian boundary and does not overlap with dinosaur bearing strata in North America supporting the hypothesis of Irmis and Mundil, 2008, 2010. The previously reported date of ~217 Ma for the middle of the formation by Shipman (2004) and Currie et al (2009) has been considered unreliable because of a lack of stratigraphic control and the inability to reproduce the methodology.
-The Ischigualasto is divided into three biozones based on vertebrate fossil occurrences. One of the boundaries is supposed to represent the Carnian/Norian boundary, although it seems to me that these boundaries are somewhat ambiguous as they all depend on negative evidence.
-Placing the vertebrate occurrences in stratigraphic order suggests to the authors that rhynchosaurs went extinct at the Carnian/Norian boundary. Interestingly they also propose that dinosaurs went extinct locally and did not reappear in the area until deposition of the Los Colorados Formation later in the Norian.
Martinez, R. N., Sereno, P. C., Alcober, O. A., Colombi, C. E., Renne, P. R., Montañez, I. P., and B. S. Currie. 2011. A Basal Dinosaur from the Dawn of the Dinosaur Era in Southwestern Pangaea. Science 331:206-210 DOI: 10.1126/science.1198467.
Abstract - Upper Triassic rocks in northwestern Argentina preserve the most complete record of dinosaurs before their rise to dominance in the Early Jurassic. Here, we describe a previously unidentified basal theropod, reassess its contemporary Eoraptor as a basal sauropodomorph, divide the faunal record of the Ischigualasto Formation with biozones, and bracket the formation with 40Ar/39Ar ages. Some 230 million years ago in the Late Triassic (mid Carnian), the earliest dinosaurs were the dominant terrestrial carnivores and small herbivores in southwestern Pangaea. The extinction of nondinosaurian herbivores is sequential and is not linked to an increase in dinosaurian diversity, which weakens the predominant scenario for dinosaurian ascendancy as opportunistic replacement.
New Scientist article by Jeff Hecht here. Other links at Live Science and the BBC.
One point of contention in all of these analyses is the phylogenetic position of Eoraptor lunensis from the Upper Triassic Ischigualasto Formation. Originally considered the basal most theropod (e.g., Sereno et al. 1993), recent analysis have supported this hypothesis (Ezcurra, 2006, 2010; Nesbitt et al., 2009) or cast it as a basal saurischian outside of Eusaurischia (e.g., Langer, 2004; Langer and Benton, 2004; Upchurch et al., 2007; Yates, 2007; Martinez and Alcober, 2009).
A new paper out today in Science by Martinez et al. describes a new basal theropod taxon, Eodromaeus murphi, from the Ischigualasto Formation. This new taxon is known by much of the skeleton and represents the new theropod previously mentioned by Martinez et al. (2008). A phylogenetic analysis places Eodromaeus within Theropoda as the sister taxon to Neotheropoda (a position previously held by Tawa, which in this new analysis is a neotheropod) and the sister taxon to the herrerasaurid theropods.
Very striking in this analysis is the recovery of Eoraptor lunensis not only as a Eusaurischian but as a stem-sauropodomorph in a polytomy with Panphagia and Saturnalia (thus it would be a saturnaliine according to Ezcurra 2010; Guaibasaurus and Chromogisaurus were not included in the analysis). This positioning for Eoraptor had previously been alluded to by Martinez and Alcobar (2009), but this is the first time it has been supported by a phylogenetic analysis.
I'm sure this new analysis will cause quite a debate among basal dinosaur workers, especially regarding the ideas of taxon sampling and character inclusion/codings in phylogenetic analyses. The analysis by Martinez et al. excludes lots of incomplete/poorly known taxa as well as taxa that these authors percieve as being too far out phylogentically to have consequence to the question of basal dinosaur relationships. The character matrix is an updated version of Sereno (1999) and does not utilize many characters found in other studies such as Langer and Benton (2006), Ezcurra (2006), and Nesbitt et al. (2009). I don't really have a horse in this race given that I don't have a basal dinosaur analysis that I am personally working on, but as someone outside looking in, it is really difficult to compare across these various analyses given the strong differences in datasets being utilized. Hopefully we will see a consensus at some point.
Nonetheless, if Eoraptor is indeed found to be a basal sauropodomorph, this is of great interest because it gets us a step closer to seeing what the common ancestor of theropods and sauropodomorphs may have looked like.
Some other neat tidbits and conclusions from the paper:
-Like Eoraptor, Eodromaeous possesses a small row of teeth on the palatal ramus of the pterygoid.
-A new radioisotopic date for the top of the Ischigualasto Formation constrains the majority of the formation between 231.4 Ma and 225.9Ma, thus the Ischigualasto Formation spans the Carnian/Norian boundary and does not overlap with dinosaur bearing strata in North America supporting the hypothesis of Irmis and Mundil, 2008, 2010. The previously reported date of ~217 Ma for the middle of the formation by Shipman (2004) and Currie et al (2009) has been considered unreliable because of a lack of stratigraphic control and the inability to reproduce the methodology.
-The Ischigualasto is divided into three biozones based on vertebrate fossil occurrences. One of the boundaries is supposed to represent the Carnian/Norian boundary, although it seems to me that these boundaries are somewhat ambiguous as they all depend on negative evidence.
-Placing the vertebrate occurrences in stratigraphic order suggests to the authors that rhynchosaurs went extinct at the Carnian/Norian boundary. Interestingly they also propose that dinosaurs went extinct locally and did not reappear in the area until deposition of the Los Colorados Formation later in the Norian.
Martinez, R. N., Sereno, P. C., Alcober, O. A., Colombi, C. E., Renne, P. R., Montañez, I. P., and B. S. Currie. 2011. A Basal Dinosaur from the Dawn of the Dinosaur Era in Southwestern Pangaea. Science 331:206-210 DOI: 10.1126/science.1198467.
Abstract - Upper Triassic rocks in northwestern Argentina preserve the most complete record of dinosaurs before their rise to dominance in the Early Jurassic. Here, we describe a previously unidentified basal theropod, reassess its contemporary Eoraptor as a basal sauropodomorph, divide the faunal record of the Ischigualasto Formation with biozones, and bracket the formation with 40Ar/39Ar ages. Some 230 million years ago in the Late Triassic (mid Carnian), the earliest dinosaurs were the dominant terrestrial carnivores and small herbivores in southwestern Pangaea. The extinction of nondinosaurian herbivores is sequential and is not linked to an increase in dinosaurian diversity, which weakens the predominant scenario for dinosaurian ascendancy as opportunistic replacement.
New Scientist article by Jeff Hecht here. Other links at Live Science and the BBC.
Teumbaita sulcognathus, a new Rhynchosaur from the Late Triassic of Brazil
Another late 2010 paper. I like the detailed locality data given showing the local stratigraphic position of specimens collected from these areas.
Montefeltro, F. C., Langer, M. C., and C. L. Schultz. 2010. Cranial anatomy of a new genus of hyperodapedontine rhynchosaur (Diapsida, Archosauromorpha) from the Upper Triassic of southern Brazil. Earth and Environmental Science Transactions of the Royal Society of Edinburgh 101: 27–52. DOI: 10.1017/S1755691010009060
Abstract - Detailed description of the cranial anatomy of the rhynchosaur previously known as Scaphonyx sulcognathus allows its assignment to a new genus Teyumbaita. Two nearly complete skulls and a partial skull have been referred to the taxon, all of which come from the lower part of the Caturrita Formation, Upper Triassic of Rio Grande do Sul, southern Brazil. Cranial autapomorphies of Teyumbaita sulcognathus include anterior margin of nasal concave at midline, prefrontal separated from the ascending process of the maxilla, palatal ramus of pterygoid expanded laterally within palatines, dorsal surface of exoccipital markedly depressed, a single tooth lingually displaced from the main medial tooth-bearing area of the maxilla, and a number of other characters (such as skull broader than long; a protruding orbital anterior margin; anguli oris extending to anterior ramus of the jugal; bar between the orbit and the lower temporal fenestra wider than 0·4 of the total orbital opening; mandibular depth reaching more than 25 of the total length) support its inclusion in Hyperodapedontinae. T. sulcognathus is the only potential Norian rhynchosaur, suggesting that the group survived the end-Carnian extinction event.
Montefeltro, F. C., Langer, M. C., and C. L. Schultz. 2010. Cranial anatomy of a new genus of hyperodapedontine rhynchosaur (Diapsida, Archosauromorpha) from the Upper Triassic of southern Brazil. Earth and Environmental Science Transactions of the Royal Society of Edinburgh 101: 27–52. DOI: 10.1017/S1755691010009060
Abstract - Detailed description of the cranial anatomy of the rhynchosaur previously known as Scaphonyx sulcognathus allows its assignment to a new genus Teyumbaita. Two nearly complete skulls and a partial skull have been referred to the taxon, all of which come from the lower part of the Caturrita Formation, Upper Triassic of Rio Grande do Sul, southern Brazil. Cranial autapomorphies of Teyumbaita sulcognathus include anterior margin of nasal concave at midline, prefrontal separated from the ascending process of the maxilla, palatal ramus of pterygoid expanded laterally within palatines, dorsal surface of exoccipital markedly depressed, a single tooth lingually displaced from the main medial tooth-bearing area of the maxilla, and a number of other characters (such as skull broader than long; a protruding orbital anterior margin; anguli oris extending to anterior ramus of the jugal; bar between the orbit and the lower temporal fenestra wider than 0·4 of the total orbital opening; mandibular depth reaching more than 25 of the total length) support its inclusion in Hyperodapedontinae. T. sulcognathus is the only potential Norian rhynchosaur, suggesting that the group survived the end-Carnian extinction event.
2010 Paper on the Osteology of the Procolophonid Leptopleuron lacertinum Owen
Thanks to Ian Corfe for bringing this to my attention:
Säilä, L. K. 2010. Osteology of Leptopleuron lacertinum Owen, a procolophonoid parareptile from the Upper Triassic of Scotland, with remarks on ontogeny, ecology and affinities. Earth and Environmental Science Transactions of the Royal Society of Edinburgh, 101, 1–25.
Abstract - The Late Triassic reptile Leptopleuron lacertinum Owen, 1851 is described for the first time in full anatomical detail, based on newly produced silicone and plastic casts of the numerous specimens preserved as natural moulds. Previously, only the braincase has been described from these detailed casts. Leptopleuron is reconstructed as a 270-mm-long reptile with a long tail, although it is possible that even the largest known specimens were still sub-adults. Within Procolophonoidea, Leptopleuron is distinguished by the following non-braincase autapomorphies: two flattened, triangular spines of equal size on the quadratojugal; V-shaped groove on the jugal; the anterior tip of the jugal in contact with the posterolateral extension of the nasal; minimal contact between the jugal and the postorbital; frontals narrow anterior to the orbitotemporal openings; the vomerine dentition consisting of a tall and a short pair of fangs; broad medial ridge of pleurocentra of the dorsal vertebrae divided into three separate ridges by two deep grooves on each pleurocentrum; distinct three-fold depression pattern on the ventral side of ischium; and the first phalanx on the fifth pedal digit being long and slim. Leptopleuron shares some features with living sand lizards and might have lived a burrowing lifestyle. The dentition and body shape of Leptopleuron imply it ate a diet of fibrous plant material or hard-shelled invertebrates.
Säilä, L. K. 2010. Osteology of Leptopleuron lacertinum Owen, a procolophonoid parareptile from the Upper Triassic of Scotland, with remarks on ontogeny, ecology and affinities. Earth and Environmental Science Transactions of the Royal Society of Edinburgh, 101, 1–25.
Abstract - The Late Triassic reptile Leptopleuron lacertinum Owen, 1851 is described for the first time in full anatomical detail, based on newly produced silicone and plastic casts of the numerous specimens preserved as natural moulds. Previously, only the braincase has been described from these detailed casts. Leptopleuron is reconstructed as a 270-mm-long reptile with a long tail, although it is possible that even the largest known specimens were still sub-adults. Within Procolophonoidea, Leptopleuron is distinguished by the following non-braincase autapomorphies: two flattened, triangular spines of equal size on the quadratojugal; V-shaped groove on the jugal; the anterior tip of the jugal in contact with the posterolateral extension of the nasal; minimal contact between the jugal and the postorbital; frontals narrow anterior to the orbitotemporal openings; the vomerine dentition consisting of a tall and a short pair of fangs; broad medial ridge of pleurocentra of the dorsal vertebrae divided into three separate ridges by two deep grooves on each pleurocentrum; distinct three-fold depression pattern on the ventral side of ischium; and the first phalanx on the fifth pedal digit being long and slim. Leptopleuron shares some features with living sand lizards and might have lived a burrowing lifestyle. The dentition and body shape of Leptopleuron imply it ate a diet of fibrous plant material or hard-shelled invertebrates.
Looking Closely at the Correlation Between Marine Species Loss and Ecosystem Collapse and Recovery
Whiteside, J. H., and P. D. Ward. 2011. Ammonoid diversity and disparity track episodes of chaotic carbon cycling during the early Mesozoic. Geology 39: 99-102. doi: 10.1130/G31401.1
Abstract - Episodes of mass extinction represent the largest events of biodiversity loss known in the geologic record, and may provide tests of biodiversity-ecosystem stability hypotheses. Here we present the first correlation between ammonoid diversity and disparity and ecosystem stability as represented by stable carbon isotopic records spanning the end-Permian through end-Triassic mass extinctions. Ammonoid generic richness from a single biogeographic realm shows that nearly all taxa disappeared coincident with major carbon isotopic shifts to lighter values. The intervals following these two major mass extinctions were characterized by multiple positive-negative couplets of chaotic carbon cycling and were composed of low-richness ammonoid faunas characterized by higher proportions of passively floating, non-swimming morphotypes than before or after. In contrast, richness was highest during intervals of stable carbon isotope values. We propose that these “chaotic carbon episodes” reflect the breakdown of functional redundancy in the ecosystem, and that the post-extinction carbon cycle did not stabilize until redundancy was restored.
Press release for this article here.
Abstract - Episodes of mass extinction represent the largest events of biodiversity loss known in the geologic record, and may provide tests of biodiversity-ecosystem stability hypotheses. Here we present the first correlation between ammonoid diversity and disparity and ecosystem stability as represented by stable carbon isotopic records spanning the end-Permian through end-Triassic mass extinctions. Ammonoid generic richness from a single biogeographic realm shows that nearly all taxa disappeared coincident with major carbon isotopic shifts to lighter values. The intervals following these two major mass extinctions were characterized by multiple positive-negative couplets of chaotic carbon cycling and were composed of low-richness ammonoid faunas characterized by higher proportions of passively floating, non-swimming morphotypes than before or after. In contrast, richness was highest during intervals of stable carbon isotope values. We propose that these “chaotic carbon episodes” reflect the breakdown of functional redundancy in the ecosystem, and that the post-extinction carbon cycle did not stabilize until redundancy was restored.
Press release for this article here.
Koskinonodon it is!
Mueller (2007) noted that the name Buettneria Case 1922, for the large Late Triassic metoposaurid from the United States, was preoccupied, and recommended the next available name Koskinonodon Branson and Mehl 1929 as the replacement name for this taxon.
Subsequently Lucas et al. (2007) petitioned the International Committee of Zoological Nomenclature (ICZN) to conserve this name. Details of the case and comments are available here (click expand on Case 3420). The final opinion can be found here.
Main Reference:
Mueller, B. D. 2006. Koskinonodon Branson and Mehl, 1929, a replacement name for the preoccupied temnospondyl Buettneria Case, 1922. Journal of Vertebrate Paleontology 27:225.
Subsequently Lucas et al. (2007) petitioned the International Committee of Zoological Nomenclature (ICZN) to conserve this name. Details of the case and comments are available here (click expand on Case 3420). The final opinion can be found here.
Main Reference:
Mueller, B. D. 2006. Koskinonodon Branson and Mehl, 1929, a replacement name for the preoccupied temnospondyl Buettneria Case, 1922. Journal of Vertebrate Paleontology 27:225.
New Ichtyosaur Material from the Middle Triassic of China
First Triassic themed paper of 2011.
Liu, J., Aitchison, J.C.,Sun, Y.-Y., Zhang, Q.-Y., Zhou, C.-Y., and T. Lv. 2011. New Mixosaurid Ichthyosaur Specimen from the Middle Triassic of SW China: Further Evidence for the Diapsid Origin of Ichthyosaurs. Journal of Paleontology 85(1):32-36. doi: 10.1666/09-131.1
Abstract - Recent cladistic analyses have all suggested a diapsid origin of ichthyosaurs. However, an intermediate evolutionary stage of the lower temporal region of ichthyosaurian skull between basal diapsids and derived ichthyosaurs has been absent from the fossil record. Here we describe the cranial skeleton of a new mixosaurid ichthyosaur specimen with a well-preserved lower temporal region from the Anisian Guanling Formation of eastern Yunnan. It is characterized by the most primitive lower temporal region within known ichthyosaurs. The primitive characters of the lower temporal region include both external and internal separation between the jugal and the quadratojugal, an anterior process of the quadratojugal, an apparent posteroventral process of the jugal, and a large lower temporal opening surrounded by the jugal, the postorbital, the squamosal, and the quadratojugal. The lower temporal region of this specimen provides the most direct evidence to the diapsid origin of ichthyosaurs. It also suggests that the disappearance of the lower temporal fenestra is caused initially by the reduction of the lower temporal arcade rather than the enlargement of the surrounding bones.
Liu, J., Aitchison, J.C.,Sun, Y.-Y., Zhang, Q.-Y., Zhou, C.-Y., and T. Lv. 2011. New Mixosaurid Ichthyosaur Specimen from the Middle Triassic of SW China: Further Evidence for the Diapsid Origin of Ichthyosaurs. Journal of Paleontology 85(1):32-36. doi: 10.1666/09-131.1
Abstract - Recent cladistic analyses have all suggested a diapsid origin of ichthyosaurs. However, an intermediate evolutionary stage of the lower temporal region of ichthyosaurian skull between basal diapsids and derived ichthyosaurs has been absent from the fossil record. Here we describe the cranial skeleton of a new mixosaurid ichthyosaur specimen with a well-preserved lower temporal region from the Anisian Guanling Formation of eastern Yunnan. It is characterized by the most primitive lower temporal region within known ichthyosaurs. The primitive characters of the lower temporal region include both external and internal separation between the jugal and the quadratojugal, an anterior process of the quadratojugal, an apparent posteroventral process of the jugal, and a large lower temporal opening surrounded by the jugal, the postorbital, the squamosal, and the quadratojugal. The lower temporal region of this specimen provides the most direct evidence to the diapsid origin of ichthyosaurs. It also suggests that the disappearance of the lower temporal fenestra is caused initially by the reduction of the lower temporal arcade rather than the enlargement of the surrounding bones.
Triassic Literature Recap - 2010
It's time again to list all of the literature published on Triassic vertebrate paleontology in 2010. Most of these papers were announced on this site; however, some slipped through the cracks. Even with those inclusions this list is not entirely exhaustive given the sheer volume of work out there and the plethora of scientific journals.
Temnospondyl studies cooled off a little in 2010 compared with past years, while synapsids and pterosaurs remained hot. Permo-Triassic and end Triassic extinction interval studies continue on a rapid pace. In the world of dinosaurs we had a new herrerrasaur, Sanjuansaurus, and found out that Azendohsaurus was not. I'm always thrilled when new aetosaur papers our published and in 2010 we had a new species of Stagonolepis, an armor histology study, two papers on Typothorax, and a revision of Lucasuchus hunti. Amazingly there were actually two new papers this year dealing with phytosaurs, including a new taxon from the Petrified Forest. The most prominent Triassic reference this year, however, was the new book, "Triassic Life on Land: The great transition" by Hans Sues and Nick Fraser. I encourage all Triassophiles who have not yet picked up this book to do so.
In 2009 the most prolific Triassic author for vertebrate paleontology papers was Cesar Schultz with six papers. This year it is Spencer Lucas with eight. Sterling Nesbitt is right behind with six. Let's hope 2011 is as productive for Triassic research as the past years.
Abdala, F., and Ribeiro, A.M. 2010. Distribution and diversity patterns of Triassic cynodonts (Therapsida, Cynodontia) in Gondwana. Palaeogeography, Palaeoclimatology, Palaeoecology 286:202-217.
Alcober, O. A., and Martinez, R. N. 2010. A new herrerasaurid (Dinosauria, Saurischia) from the Upper Triassic of Ischigualasto Formation of northwestern Argentina. ZooKeys 63: 55-81.
Allington-Jones, L., Braddy, S. J., and Trueman, C. N. 2010. Palaeoenvironmental implications of the ichnology and geochemistry of the Westbury Formation (Rhaetian), Westburyon- Severn, South-West England. Palaeontology 53:491-506.
Benson, R. B. J., Butler, R. J., Lindgren, J., and Smith, A. S. 2010. Mesozoic marine tetrapod diversity: mass extinctions and temporal heterogeneity in geological megabiases affecting vertebrates. Proceedings of the Royal Society, Series B 277:820-834.
Benton, M. J. 2010. Archosaur remains from the Otter Sandstone Formation (Middle Triassic, late Anisian) of Devon, southern UK. Proceedings of the Geologists' Association (early online), doi:10.1016/j.pgeola.2010.08.004.
Bonaparte, J. F., Schultz, C. L., and M. B. Soares. 2010. Pterosauria from the Late Triassic of Southern Brazil, pp. 63-71 in Bandyopadhyay, S. (ed.), New Aspects of Mesozoic Biodiversity, Lecture Notes in Earth Sciences 132, Springer-Verlag Berlin/ Heidelberg, DOI: 10.1007/978-3-642-10311-7
Botha-Brink, J., and Angielczyk, K. D. 2010. Do extraordinarily high growth rates in Permo-Triassic dicynodonts (Therapsida, Anomodontia) explain theic success before and after the end-Permian extinction? Zoological Journal of the Linnean Society 160: 341-365.
Böttcher, R. 2010. Description of the shark egg capsule Palaeoxyris friessi n. sp. From the Ladinian (Middle Triassic) of SW Germany and discussion of all known egg capsules from the Triassic of the Germanic Basin. Palaeodiversity 3: 123–139.
Brinkmann, W., Romano, C., Bucher, H,. Ware, D., and Jenks, J. 2010. Palaeobiogeography and stratigraphy of advanced gnathostomian fishes (Chondrichthyes and Osteichthyes) in the Early Triassic and from selected Anisian Localities (Report 1863-2009). Zentrallblatt fur Geologie und Palaontologie Teil II, Heft, 5/6: 765-812.
Brusatte, S. L., Niedzwiedzki, G., and Butler, R. J. 2010. Footprints pull origin and disversification of dinosaur stem lineage deep into the Early Triassic. Proceedings of the Royal Society, Series B., published on line, 7pp.
Brusatte, S. L., Benton, M. J., Desojo, J. B., Langer, M. C. 2010. The higher-level phylogeny of Archosauria (Tetrapoda: Diapsida). Journal of Systematic Palaeontology 8:3-47.
Brusatte, S. J., Nesbitt, S. J., Irmis, R. B., Butler, R. J., Benton, M. J., and Norell, M. A. 2010. The origin and early radiation of dinosaurs. Earth-Science Reviews 101:68-100.
Budziszewska-Karwowska, E., Bujok, A., and Sadlok, G. 2010. Bite marks on an Upper Triassic dicynodontid tibia from Zawiercie, Krakow-Czestochowa upland, Southern Poland. Palaios 25: 415-421.
Buchwitz, M. and S. Voigt. 2010. Peculiar carapace structure of a Triassic chroniosuchian implies evolutionary shift in trunk flexibility. Journal of Vertebrate Paleontology 30:1697-1708.
Cerda, I. A., and J. B. Desojo. 2010: Dermal armour histology of aetosaurs (Archosauria: Pseudosuchia), from the Upper Triassic of Argentina and Brazil. Lethaia, DOI: 10.1111/j.1502-3931.2010.00252.x.
Cisneros, J. C., and Ruta, M. 2010. Morphological diversity and biogeography of procolophonids (Amniota: Parareptilia). Journal of Systematic Palaeontology 8:607-625.
Cisneros, J. C., Cabral, U. G., Beer, F de, Damiani, R., and Fortier D. C. 2010 Spondarthritis in the Triassic. PLoS ONE 5, 5 pp.
Deenen, M. H. L., Ruhl, M., Bonis, N. R., Krigsman, W., Kuerschner, W. M. Reitsma, M., and van Bergen, M. J. 2010. A new chronology for the end-Triassic mass extinction. Earth and Planetary Sciences Letters 291: 113-125.
Dias-Da-Silva, S., and Milner, A. R. 2010. The pustulated temnospondyl revisited-a plagiosternine plagiosaurid from the Lower Triassic of Brazil. Acta Palaeontlogica Polonica 55: 561-563.
Diedrich, C. J. 2010. Palaeoecology of Placodus gigas (Reptilia) and other placodontids -- Middle Triassic macroalgae feeders in the Germanic basin of central Europe--and evidence for convergent evolution with Sirenia. Palaeogeography, Palaeoclimatology, Palaeoecology 285:287-306.
Ezcurra, M. D. 2010. Biogeography of Triassic tetrapods: evidence for provincialism and driven sympatric cladogensis in the early evolution of modern tetrapod lineages. Proceedings of the Royal Society, Series B 277:2547-2552.
Ezcurra, M. D. 2010. A new early dinosaur (Saurischia: Sauropodomorpha) from the Late Triassic of Argentina: a reassessment of dinosaur origin and phylogeny. Journal of Systematic Paleontology 8: 371-425.
Ezcurra, M. D., Lecuona, A., and Martinelli, A. 2010. A new basal archosauriform diapsid from the Lower Triassic of Argentina. Journal of Vertebrate Paleontology 30: 1433-1450.
Fischer, J., Axsmith, B. J., and Ash, S. R. 2010. First unequivocal record of the hybodont shark egg capsule Palaeoxyris in the Mesozoic of North America: Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 255: 327-344.
Flynn, J. J., Nesbitt, S. J., Parrish, M., Raniovohartmanana, L., and Wyss, A. R. 2010. A new species of Azendohsaurus (Diapaida: Archosauromorpha) from the Triassic Isalo Group of Southwestern Madagascar: cranium and mandible. Palaeontology 53:660-688.
Fröbisch, J., Angiekczyk, K. D., and Sidor, C. A. 2010. The Triassic dicynodont Kombuisia (Synapsida, Anomodontia) from Antarctica, a refuge from the terrestrial Permian-Triassic mass extinction. Naturwissenschaften 97: 187-196.
Gand, G., De la Horra, R., Galan-Abellan, B., Lopez-Gomez, J., Barrenechea, J. F., Arche, A., and Isabel Benito, M. 2010. New ichnites from the Middle Triassic of the Iberian Ranges (Spain): paleonenvironmental and paleogeographical implications: Historical Biology 22: 40-56.
Gao, K.-Q., Fox, R. C., Zhou, C.-F., and Li, D.-Q. 2010. A new nomammalian eucynodont (Synapsida: Therapsida) from the Triassic of Northern Gansu Province, China, and its biostratigraphic and biogeographic lmplications. American Museum Novitates 3685, 25pp.
Giordano, N., Rigo, M., Ciarapica G. & Bertinelli A. 2010. New biostratigraphical constraints for the Norian ⁄Rhaetian boundary: data from Lagonegro Basin, Southern Apennines, Italy. Lethaia, 10.1111/j.1502-3931.2010.00219.x.
Green, J. L., Schweitzer, M. H., and Lamm, E.-T. 2010. Limb bone histology and growth in Placerias hesternus (Therapsida: Anomodontia) from the Upper Triassic of North America. Palaeontology 53: 347-364.
Heckert, A. B., Lucas, S. G., Rinehart, L. F., Celeskey, M. D., Spielmann, J. A., and Hunt, A. P. 2010. Articulated skeletons of the aetosaur Typothorax coccinarum Cope (Archosauria: Stagonolepididae) from the Upper Triassic Bull Canyon Formation (Revueltian: Early-Mid Norian), eastern New Mexico, USA. Journal of Vertebrate Paleontology 30: 619-642.
Hu, S.-x,. Zhang, Q.-y., Chen, Z.-Q., Zhou, C.-y., Lü, T., Xie, T., Wen, W., Huang, J. -y., and M. J. Benton, 2010. The Luoping biota: exceptional preservation, and new evidence on the Triassic recovery from end-Permian mass extinction. Proceedings of the Royal Society: B (advance online publication) doi: 10.1098/rspb.2010.2235
Irmis, R. B., and Whiteside, J. H., 2010. Newly integrated approaches to studying Late Triassic terrestrial ecosystems. Palaios 25: 689-691.
Irmis, R. B., Martz, J. W., Parker, W. G., and Nesbitt, S. J. 2010. Re-evaluating the correlation between Late Triassic terrestrial vertebrate biostratigraphy and the GSSP-defined marine stages. Albertiana 38:40-52.
Jaisnoski, S. G., Rayfield, E. J., and Chinsamy, A. 2010. Mechanics of the scarf premaxilla-nasal suture in the snout of Lystrosaurus. Journal of Vertebrate Palaeontology 30:1283-1288.
Kammerer, C. F., Flynn, J. J., Ranivoharimanana, L. and A. R. Wyss. 2010. The first record of a probainognathian (Cynodontia: Chiniquodontidae) from the Triassic of Madagascar. Journal of Vertebrate Paleontology 30:1889-1894.
Kemp, T. 2010. New Perspectives on the Evolution of Late Palaeozoic and Mesozoic Terrestrial Tetrapods; pp. 1-26 in S. Bandyopadhyay (ed.), New Aspects of Mesozoic Biodiversity, Lecture Notes in Earth Sciences 132, DOI 10.1007/978-3-642-10311-7
Kimmig, J., and G. Arp. 2010. Phytosaur remains from the Norian Arnstadt Formation (Leine Valley, Germany), with reference to European phytosaur habitats. Palaeodiversity 3: 215–224.
Klein, N. 2010. Long bone histology of sauropterygia from the Lower Muschelkalk of the Germanic Basin Provides unexpected implications for phylgeny. PLoS ONE 5, 25 pp.
Klein, H., and Lucas, S. G. 2010. Tetrapod footprints - their use in biostratigraphy and biochronology of the Triassic; pp. 419-446 in Lucas, S.G. (ed.) The Triassic Timescale, Geological Society of London, Special Publications.
Klein, H., and Lucas, S. G. 2010. The Triassic footprint record of crocodylomorphs-a critical re-evaluation. New Mexico Museum of Natural History and Science Bulletin 51:55-60.
Klein, H., Voigt, S., Hminna, A., Saber, H., Schneider, J., and D. Hmich. 2010. Early Triassic Archosaur-Dominated Footprint Assemblage from the Argana Basin (Western High Atlas, Morocco). Ichnos 17:1–13. DOI: 10.1080/10420940.2010.510030
Langer, M. C. , Montefeltro, F. C. , Hone, D. E. , Whatley, R. and C. L. Schultz. 2010. On Fodonyx spenceri and a new rhynchosaur from the Middle Triassic of Devon. Journal of Vertebrate Paleontology 30:1884 -1888.
Liu, J., and Sues, H.-D. 2010. Dentition and tooth replacement of Boreogomphodon (Cynodontia: Traversodontidae) from the Upper Triassic of North Carolina, USA. Vertebrata PalAsiatica 40: 169-184.
Liu, J., and Olsen, P. 2010. The phylogenetic relationships of Eucynodontia (Amniota: Synapsada). Journal of Mammal Evolution 17: 151-176.
Liutkus, C. M., Beard, J. S., Fraser, N. C., and Ragland, P. C. 2010. Use of fine-scale stratigraphy and chemostratigraphy to evaluate conditions of deposition and preservation of a Triassic Lagerstätte, south-central Virginia. Journal of Paleolimnology 44: 645-666.
Lopez-Arbarello, A., Rauhut, O.W.M, and E. Cerdeno. 2010. The Triassic fish faunas of the Cuyana Basin, western Argentina. Palaeontology 53:249-276.
Lucas, S. G., Spielmann, J. A., Klein, H., and Lerner, A. J. 2010. Ichnology of the Upper Triassic (Apachean) Redonda Formation, east-central New Mexico. New Mexico Museum of Natural History and Science Bulletin 47:1-74.
Lucas, S. G., Rinehart, L. F., Krainer, K., Spielmann, J. A., and A. B. Heckert. 2010. Taphonomy of the Lamy amphibian quarry: A Late Triassic bonebed in New Mexico, U.S.A. Palaeogeography, Palaeoclimatology, Palaeoecology 298:388–398.
Lyson, T. R., Bever, G. S., Bhullar, B. S., Joyce, W. G., and Gauthier, J. G. 2010. Transitional fossils and the origin of turtles. Biology Letters, published on line, 4pp.
Maisch, M. W. and Kapitzke, M. 2010. A presumably marine phytosaur (Reptilia: Archosauria) from the pre-planorbis beds (Hettangian) of England. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 257: 373–379.
Mallison, H. 2010. The digital Plateosaurus 1: body mass, mass distribution and posture assessd using CAD and CAE on a digitally mounted complete skeleton. Palaeontologia Electronica 13.2.8A.
Mallison, H. 2010. The digital Plateosaurus II: An assessment of the range of motion of the limbs and vertebral column and of previous reconstructions using a digital skeletal mount. Acata Palaeontologica Polonica 55: 433-458.
Mannion, P. D., and Upchurch, P. 2010. Completeness metrics and the quality of the sauropodomorph fossil record through geological and historical time. Paleobiology 36:283-302.
Marsicano, C.A., Mancuso, A.C., Palma, R.M., and Krapovickas, V. 2010. Tetrapod tracks in a marginal lacustrine setting (Middle Triassic, Argentina): taphonomy and significance. Palaeogeography, Palaeoclimatology, Palaeoecology 291:388-399.
Martin, T., Sun, G., and Mosbrugger, V. 2010. Triassic-Jurassic biodiversity, ecosystems, and climate in the Junggar Basin, Xinjinag, northwest China. Palaeobiodiveristy and Palaeoenvironments 90:171-173.
Martinelli, A. G. 2010. On the postcanine dentition of Pascualgnathus polanskii Bonaparte (Cynodontia, Traversodontidae) from the Middle Triassic of Argentina. Geobios 43:629–638.
Mitchell, J. S., Heckert, A. B., and H.-D. Sues. 2010. Grooves to tubes: evolution of the venom delivery system in a Late Triassic “reptile”. Naturwissenschaften 97:1117-1121.
Modesto, S. P., and Botha-Brink, J. 2010. A burrow cast with Lystrosaurus skeletal remains from the Lower Triassic of South Africa. Palaios 25: 274-281.
Modesto, S. P., Scott, D. M., Botha-Brink, J, and Reisz, R. R. 2010. A new and unusual procolophonid parareptile from the Lower Triassic Katberg Formation of South Africa. Journal of Vertebrate Paleontology 30: 715-723.
Mukherjee, D., Ray, S., and Sengupta, D. P. 2010. Preliminary observations on the bone microstucture, growth patterns, and life habits of some Triassic temnospondyls from India. Journal of Vertebrate Paleontology 30: 78-93.
Nesbitt, S. J., and D. W. E. Hone. 2010. An external mandibular fenestra and other archosauriform character states in basal pterosaurs. Palaeodiversity 3: 225–233.
Nesbitt, S. J., Sidor, C. A., Irmis, R. B., Angielcyzk, K. D., Smith, R. M. H., and Tsuji, L. A. 2010. Ecologically distinct dinosaurian sister group shows early diversification of Ornithodira. Nature 464: 95-98.
Nicolas, M., and Rubidge, B. S. 2010. Changes in Permo-Triassic terrestrial tetrapod ecological representation in the Beaufort Group (Karoo Supergroup) of South Africa. Lethaia 43: 45-59.
Novikov, I. V. 2010. New data on Trematosauroid Labyrinthodonts of Eastern Europe: 2. Trematosaurus galae sp. nov.: cranial morphology. Paleontological Journal 44: 457-467.
de Oliveira, T. V., Sores, M. B., and Schultz, C. L. 2010. Trucidocynodon riograndensis gen. nov. et sp. nov. (Eucynodontia), a new cynodont from the Brazilian Upper Triassic (Santa Maria Formation). Zootaxa 2382, 71pp.
Osi, A. 2010: Feeding-related characters in basal pterosaurs: implications for jaw mechanism, dental function and diet. Lethaia, DOI: 10.1111/j.1502-3931.2010.00230.x.
Padian, K., Li, C., and Pchelnikova, J. 2010. The trackmaker of Apatopus (Late Triassic, North America): Implications for the evolution of archosaur stance and gait. Palaeontology 53: 175-189.
Parker, W. G., and Martz, J. W. 2010. Using positional homology in aetosaur (Archosauria: Pseudosuchia) osteoderms to evaluate the taxonomic status of Lucasuchus hunti. Journal of Vertebrate Paleontology 30: 1100-1108.
Piechowski, R., and Dzik, J. 2010. The axial skeleton of Silesaurus opolensis. Journal of Vertebrate Paleontology 30: 1127-1141.
Ray, S., Bandyopadhyay, S., and R. Appana. 2010. Bone Histology of a Kannemeyeriid Dicynodont Wadiasaurus: Palaeobiological Implications; pp. 73-89 in S. Bandyopadhyay (ed.), New Aspects of Mesozoic Biodiversity, Lecture Notes in Earth Sciences 132, DOI 10.1007/978-3-642-10311-7
Renesto, S. 2010. A new specimen of Nothosaurus from the Latest Anisian (Middle Triassic) Besano Formation (Grenzbitumenzone) of Italy: Rivista Italiana di Paleontologia e Stratigrafia 116: 245-260.
Renesto, S., Spielmann, J. A., Lucas, S. G., and Spagnoli, G. T. 2010. The taxonomy and paleobiology of the Late Triassic (Carnian-Norian: Adamanian-Apachean) drepanosaurs (Diapsida: Archosauromorpha: Drepanosauromorpha). New Mexico Museum of Natural History and Science Bulletin 46:1-81.
Rieppel, O., Jiang, D.-Y., Fraser, N. C., Hao, W.-C., Motani, R., Sun, Y.-L., and Sun, Z.-Y. 2010. Tanystropheus cf. T. longobardicus from the Early Late Triassic of Guizhou Province, Southwestern China. Journal of Vertebrate Paleontology 30: 1082-1089.
Rowe, T. B., Sues, H.-D., and R. Reisz. 2010. Dispersal and diversity in the earliest North American sauropodomorph dinosaurs, with a description of a new taxon. Proceedings of the Royal Society B, First Cite. doi:10.1098/rspb.2010.1867
Saila, L. K. 2010. Osteology of Leptopleuron lacertinum Owen, a procolophonoid parareptile from the Upper Triassic of Scotland, with remarks on ontogeny, ecology and affinities. Earth and Environmental Science Transactions of the Royal Society of Edinburgh, 101, 1–25.
Sanchez, S., Germain, D., De Ricqles, A., Abourachid, A., Goussard, F. and Tafforeau, P. 2010. Limb-bone histology of temnospondyls: implications for understanding the diversification of palaeoecologies and patterns of locomotion of Permo-Triassic tetrapods. Journal of Evolutionary Biology, early online. doi:10.1111/j.1420-9101.2010.02081.x
Santucci, V. L., and Kirkland, J. I. 2010. An overview of National Park Service Paleontological Resources from the Parks and Mounuments in Utah; pp. 589-623 in Sprinkel, D. A,. Chidsey, T. C., and Anderson, P. B. (eds.), Geology of Utah’s Parks and Monuments, Utah Geological Association Publication 28.
Scheyer, T. M. 2010. New interpretation of the postcranial skeleton and overall body shape of the placodont Cymodus hildegradis Peyer, 1931 (Reptilia, Sauropterygia). Palaentologia Electronica 13.2.15A.
Schoch, R. R., Voigt, S., and Buchwitz, M. 2010. A chroniosuchid from the Triassic of Kyrgyzstan and analysis of chroniosuchian relationships. Zoological Journal of the Linnean Society 160:515-530.
Schoch, R. R., Nesbitt, S., Müller, J., Lucas, S. G., and Boy, J. A., 2010. The reptile assemblage from the Moenkopi Formation (Middle Triassic) of New Mexico. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 255: 345-369.
Spielmann, J. A., and Lucas, S. G. 2010. Typothorax coccinarum (Archosauria: Stagonolepididae) from the Upper Triassic (Revueltian) Petrified Forest Formation, El Puertocito, Canon del Cobre, Rio Arriba County, New Mexico. New Mexico Museum of Natural History and Science Bulletin 49: 221-229.
Stocker, M. R. 2010. A new taxon of phytosaur (Archosauria: Pseudosuchia) from the Late Triassic (Norian) Sonsela Member (Chinle Formation) in Arizona, and a critical reevaluation of Leptosuchus Case, 1922. Palaeontology 53: 997-1022.
Sues, H.-D., and N. C. Fraser. 2010. Triassic life on land: The Great Transition. Columbia University Press, New York, 229p.
Sues, H.-D., and Hopson, J. A. 2010. Anatomy and phylogenetic relationships of Boreogomphodon jeffersoni (Cynodontia: Gomphodontia) from the Upper Triassic of Virginia. Journal of Vertebrate Paleontology 30: 1202-1220.
Sulej, T. 2010. The skull of an early Late Triassic aetosaur and the evolution of the stagonolepidid archosaurian reptiles. Zoological Journal of the Linnean Society 158:860-881.
Sullivan, C. 2010. The role of the calcaneal 'heel' as a propulsive lever in basal archosaurs and extant monitor lizards. Journal of Vertebrate Paleontology 30: 1422-1432.
Tanimoto, M., Utsunomiya, S., and Fujimoto, T. 2010. Osteichthyan teeth from the Early Triassic Taho Formation of Ehime Prefecture, Southwest Japan. Konseki 33: 49-52.
Tintori, A., Sun, Z.-Y., Lombardo, C., Jiang, D.-Y., Sun, Y.-L., and Hao, W.-C., 2010. A new basal neopterygian from the Middle Triassic of Luoping County (South China). Rivista Italiana di Paleontologia e Stratigrafia 116 (2).
Tourania, A., Benaouissa, N.,Gand, G., Bourquinc, S., Jalil, N.-E., Broutind,J., Battail, B., Germaine, D., Khaldounea, F., Soumaya, S., Steyere, J. S., and R. . 2010. Evidence of an Early Triassic age (Olenekian) in Argana Basin (High Atlas, Morocco) based on new chirotherioidtraces. Comptes Rendus Palevol, early online.
Trotteyn, M. J. and J. A. Haro. 2010. The braincase of a specimen of Proterochampsa Reig (Archosauriformes: Proterochampsidae) from the Late Triassic of Argentina. Paläontologische Zeitschrift. Published on-line May 11 2010. DOI 10.1007/s12542-010-0068-7
Witzmann, F., Scholz, H., Mueller, J., and N. Kardjilov. 2010. Sculpture and vascularization of dermal bones, and the implications for the physiology of basal tetrapods. Zoological Journal of the Linnean Society 160:302-340.
Zhao, L.-J., Sato, T., Liu, J., Li, C., and X.-C. Wu. 2010. A new skeleton of Miodentosaurus brevis (Diapsida:Thalattosauria) with a further study of the taxon. Vertebrata PalAsiatica 48:1-10.
Temnospondyl studies cooled off a little in 2010 compared with past years, while synapsids and pterosaurs remained hot. Permo-Triassic and end Triassic extinction interval studies continue on a rapid pace. In the world of dinosaurs we had a new herrerrasaur, Sanjuansaurus, and found out that Azendohsaurus was not. I'm always thrilled when new aetosaur papers our published and in 2010 we had a new species of Stagonolepis, an armor histology study, two papers on Typothorax, and a revision of Lucasuchus hunti. Amazingly there were actually two new papers this year dealing with phytosaurs, including a new taxon from the Petrified Forest. The most prominent Triassic reference this year, however, was the new book, "Triassic Life on Land: The great transition" by Hans Sues and Nick Fraser. I encourage all Triassophiles who have not yet picked up this book to do so.
In 2009 the most prolific Triassic author for vertebrate paleontology papers was Cesar Schultz with six papers. This year it is Spencer Lucas with eight. Sterling Nesbitt is right behind with six. Let's hope 2011 is as productive for Triassic research as the past years.
Abdala, F., and Ribeiro, A.M. 2010. Distribution and diversity patterns of Triassic cynodonts (Therapsida, Cynodontia) in Gondwana. Palaeogeography, Palaeoclimatology, Palaeoecology 286:202-217.
Alcober, O. A., and Martinez, R. N. 2010. A new herrerasaurid (Dinosauria, Saurischia) from the Upper Triassic of Ischigualasto Formation of northwestern Argentina. ZooKeys 63: 55-81.
Allington-Jones, L., Braddy, S. J., and Trueman, C. N. 2010. Palaeoenvironmental implications of the ichnology and geochemistry of the Westbury Formation (Rhaetian), Westburyon- Severn, South-West England. Palaeontology 53:491-506.
Benson, R. B. J., Butler, R. J., Lindgren, J., and Smith, A. S. 2010. Mesozoic marine tetrapod diversity: mass extinctions and temporal heterogeneity in geological megabiases affecting vertebrates. Proceedings of the Royal Society, Series B 277:820-834.
Benton, M. J. 2010. Archosaur remains from the Otter Sandstone Formation (Middle Triassic, late Anisian) of Devon, southern UK. Proceedings of the Geologists' Association (early online), doi:10.1016/j.pgeola.2010.08.004.
Bonaparte, J. F., Schultz, C. L., and M. B. Soares. 2010. Pterosauria from the Late Triassic of Southern Brazil, pp. 63-71 in Bandyopadhyay, S. (ed.), New Aspects of Mesozoic Biodiversity, Lecture Notes in Earth Sciences 132, Springer-Verlag Berlin/ Heidelberg, DOI: 10.1007/978-3-642-10311-7
Botha-Brink, J., and Angielczyk, K. D. 2010. Do extraordinarily high growth rates in Permo-Triassic dicynodonts (Therapsida, Anomodontia) explain theic success before and after the end-Permian extinction? Zoological Journal of the Linnean Society 160: 341-365.
Böttcher, R. 2010. Description of the shark egg capsule Palaeoxyris friessi n. sp. From the Ladinian (Middle Triassic) of SW Germany and discussion of all known egg capsules from the Triassic of the Germanic Basin. Palaeodiversity 3: 123–139.
Brinkmann, W., Romano, C., Bucher, H,. Ware, D., and Jenks, J. 2010. Palaeobiogeography and stratigraphy of advanced gnathostomian fishes (Chondrichthyes and Osteichthyes) in the Early Triassic and from selected Anisian Localities (Report 1863-2009). Zentrallblatt fur Geologie und Palaontologie Teil II, Heft, 5/6: 765-812.
Brusatte, S. L., Niedzwiedzki, G., and Butler, R. J. 2010. Footprints pull origin and disversification of dinosaur stem lineage deep into the Early Triassic. Proceedings of the Royal Society, Series B., published on line, 7pp.
Brusatte, S. L., Benton, M. J., Desojo, J. B., Langer, M. C. 2010. The higher-level phylogeny of Archosauria (Tetrapoda: Diapsida). Journal of Systematic Palaeontology 8:3-47.
Brusatte, S. J., Nesbitt, S. J., Irmis, R. B., Butler, R. J., Benton, M. J., and Norell, M. A. 2010. The origin and early radiation of dinosaurs. Earth-Science Reviews 101:68-100.
Budziszewska-Karwowska, E., Bujok, A., and Sadlok, G. 2010. Bite marks on an Upper Triassic dicynodontid tibia from Zawiercie, Krakow-Czestochowa upland, Southern Poland. Palaios 25: 415-421.
Buchwitz, M. and S. Voigt. 2010. Peculiar carapace structure of a Triassic chroniosuchian implies evolutionary shift in trunk flexibility. Journal of Vertebrate Paleontology 30:1697-1708.
Cerda, I. A., and J. B. Desojo. 2010: Dermal armour histology of aetosaurs (Archosauria: Pseudosuchia), from the Upper Triassic of Argentina and Brazil. Lethaia, DOI: 10.1111/j.1502-3931.2010.00252.x.
Cisneros, J. C., and Ruta, M. 2010. Morphological diversity and biogeography of procolophonids (Amniota: Parareptilia). Journal of Systematic Palaeontology 8:607-625.
Cisneros, J. C., Cabral, U. G., Beer, F de, Damiani, R., and Fortier D. C. 2010 Spondarthritis in the Triassic. PLoS ONE 5, 5 pp.
Deenen, M. H. L., Ruhl, M., Bonis, N. R., Krigsman, W., Kuerschner, W. M. Reitsma, M., and van Bergen, M. J. 2010. A new chronology for the end-Triassic mass extinction. Earth and Planetary Sciences Letters 291: 113-125.
Dias-Da-Silva, S., and Milner, A. R. 2010. The pustulated temnospondyl revisited-a plagiosternine plagiosaurid from the Lower Triassic of Brazil. Acta Palaeontlogica Polonica 55: 561-563.
Diedrich, C. J. 2010. Palaeoecology of Placodus gigas (Reptilia) and other placodontids -- Middle Triassic macroalgae feeders in the Germanic basin of central Europe--and evidence for convergent evolution with Sirenia. Palaeogeography, Palaeoclimatology, Palaeoecology 285:287-306.
Ezcurra, M. D. 2010. Biogeography of Triassic tetrapods: evidence for provincialism and driven sympatric cladogensis in the early evolution of modern tetrapod lineages. Proceedings of the Royal Society, Series B 277:2547-2552.
Ezcurra, M. D. 2010. A new early dinosaur (Saurischia: Sauropodomorpha) from the Late Triassic of Argentina: a reassessment of dinosaur origin and phylogeny. Journal of Systematic Paleontology 8: 371-425.
Ezcurra, M. D., Lecuona, A., and Martinelli, A. 2010. A new basal archosauriform diapsid from the Lower Triassic of Argentina. Journal of Vertebrate Paleontology 30: 1433-1450.
Fischer, J., Axsmith, B. J., and Ash, S. R. 2010. First unequivocal record of the hybodont shark egg capsule Palaeoxyris in the Mesozoic of North America: Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 255: 327-344.
Flynn, J. J., Nesbitt, S. J., Parrish, M., Raniovohartmanana, L., and Wyss, A. R. 2010. A new species of Azendohsaurus (Diapaida: Archosauromorpha) from the Triassic Isalo Group of Southwestern Madagascar: cranium and mandible. Palaeontology 53:660-688.
Fröbisch, J., Angiekczyk, K. D., and Sidor, C. A. 2010. The Triassic dicynodont Kombuisia (Synapsida, Anomodontia) from Antarctica, a refuge from the terrestrial Permian-Triassic mass extinction. Naturwissenschaften 97: 187-196.
Gand, G., De la Horra, R., Galan-Abellan, B., Lopez-Gomez, J., Barrenechea, J. F., Arche, A., and Isabel Benito, M. 2010. New ichnites from the Middle Triassic of the Iberian Ranges (Spain): paleonenvironmental and paleogeographical implications: Historical Biology 22: 40-56.
Gao, K.-Q., Fox, R. C., Zhou, C.-F., and Li, D.-Q. 2010. A new nomammalian eucynodont (Synapsida: Therapsida) from the Triassic of Northern Gansu Province, China, and its biostratigraphic and biogeographic lmplications. American Museum Novitates 3685, 25pp.
Giordano, N., Rigo, M., Ciarapica G. & Bertinelli A. 2010. New biostratigraphical constraints for the Norian ⁄Rhaetian boundary: data from Lagonegro Basin, Southern Apennines, Italy. Lethaia, 10.1111/j.1502-3931.2010.00219.x.
Green, J. L., Schweitzer, M. H., and Lamm, E.-T. 2010. Limb bone histology and growth in Placerias hesternus (Therapsida: Anomodontia) from the Upper Triassic of North America. Palaeontology 53: 347-364.
Heckert, A. B., Lucas, S. G., Rinehart, L. F., Celeskey, M. D., Spielmann, J. A., and Hunt, A. P. 2010. Articulated skeletons of the aetosaur Typothorax coccinarum Cope (Archosauria: Stagonolepididae) from the Upper Triassic Bull Canyon Formation (Revueltian: Early-Mid Norian), eastern New Mexico, USA. Journal of Vertebrate Paleontology 30: 619-642.
Hu, S.-x,. Zhang, Q.-y., Chen, Z.-Q., Zhou, C.-y., Lü, T., Xie, T., Wen, W., Huang, J. -y., and M. J. Benton, 2010. The Luoping biota: exceptional preservation, and new evidence on the Triassic recovery from end-Permian mass extinction. Proceedings of the Royal Society: B (advance online publication) doi: 10.1098/rspb.2010.2235
Irmis, R. B., and Whiteside, J. H., 2010. Newly integrated approaches to studying Late Triassic terrestrial ecosystems. Palaios 25: 689-691.
Irmis, R. B., Martz, J. W., Parker, W. G., and Nesbitt, S. J. 2010. Re-evaluating the correlation between Late Triassic terrestrial vertebrate biostratigraphy and the GSSP-defined marine stages. Albertiana 38:40-52.
Jaisnoski, S. G., Rayfield, E. J., and Chinsamy, A. 2010. Mechanics of the scarf premaxilla-nasal suture in the snout of Lystrosaurus. Journal of Vertebrate Palaeontology 30:1283-1288.
Kammerer, C. F., Flynn, J. J., Ranivoharimanana, L. and A. R. Wyss. 2010. The first record of a probainognathian (Cynodontia: Chiniquodontidae) from the Triassic of Madagascar. Journal of Vertebrate Paleontology 30:1889-1894.
Kemp, T. 2010. New Perspectives on the Evolution of Late Palaeozoic and Mesozoic Terrestrial Tetrapods; pp. 1-26 in S. Bandyopadhyay (ed.), New Aspects of Mesozoic Biodiversity, Lecture Notes in Earth Sciences 132, DOI 10.1007/978-3-642-10311-7
Kimmig, J., and G. Arp. 2010. Phytosaur remains from the Norian Arnstadt Formation (Leine Valley, Germany), with reference to European phytosaur habitats. Palaeodiversity 3: 215–224.
Klein, N. 2010. Long bone histology of sauropterygia from the Lower Muschelkalk of the Germanic Basin Provides unexpected implications for phylgeny. PLoS ONE 5, 25 pp.
Klein, H., and Lucas, S. G. 2010. Tetrapod footprints - their use in biostratigraphy and biochronology of the Triassic; pp. 419-446 in Lucas, S.G. (ed.) The Triassic Timescale, Geological Society of London, Special Publications.
Klein, H., and Lucas, S. G. 2010. The Triassic footprint record of crocodylomorphs-a critical re-evaluation. New Mexico Museum of Natural History and Science Bulletin 51:55-60.
Klein, H., Voigt, S., Hminna, A., Saber, H., Schneider, J., and D. Hmich. 2010. Early Triassic Archosaur-Dominated Footprint Assemblage from the Argana Basin (Western High Atlas, Morocco). Ichnos 17:1–13. DOI: 10.1080/10420940.2010.510030
Langer, M. C. , Montefeltro, F. C. , Hone, D. E. , Whatley, R. and C. L. Schultz. 2010. On Fodonyx spenceri and a new rhynchosaur from the Middle Triassic of Devon. Journal of Vertebrate Paleontology 30:1884 -1888.
Liu, J., and Sues, H.-D. 2010. Dentition and tooth replacement of Boreogomphodon (Cynodontia: Traversodontidae) from the Upper Triassic of North Carolina, USA. Vertebrata PalAsiatica 40: 169-184.
Liu, J., and Olsen, P. 2010. The phylogenetic relationships of Eucynodontia (Amniota: Synapsada). Journal of Mammal Evolution 17: 151-176.
Liutkus, C. M., Beard, J. S., Fraser, N. C., and Ragland, P. C. 2010. Use of fine-scale stratigraphy and chemostratigraphy to evaluate conditions of deposition and preservation of a Triassic Lagerstätte, south-central Virginia. Journal of Paleolimnology 44: 645-666.
Lopez-Arbarello, A., Rauhut, O.W.M, and E. Cerdeno. 2010. The Triassic fish faunas of the Cuyana Basin, western Argentina. Palaeontology 53:249-276.
Lucas, S. G., Spielmann, J. A., Klein, H., and Lerner, A. J. 2010. Ichnology of the Upper Triassic (Apachean) Redonda Formation, east-central New Mexico. New Mexico Museum of Natural History and Science Bulletin 47:1-74.
Lucas, S. G., Rinehart, L. F., Krainer, K., Spielmann, J. A., and A. B. Heckert. 2010. Taphonomy of the Lamy amphibian quarry: A Late Triassic bonebed in New Mexico, U.S.A. Palaeogeography, Palaeoclimatology, Palaeoecology 298:388–398.
Lyson, T. R., Bever, G. S., Bhullar, B. S., Joyce, W. G., and Gauthier, J. G. 2010. Transitional fossils and the origin of turtles. Biology Letters, published on line, 4pp.
Maisch, M. W. and Kapitzke, M. 2010. A presumably marine phytosaur (Reptilia: Archosauria) from the pre-planorbis beds (Hettangian) of England. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 257: 373–379.
Mallison, H. 2010. The digital Plateosaurus 1: body mass, mass distribution and posture assessd using CAD and CAE on a digitally mounted complete skeleton. Palaeontologia Electronica 13.2.8A.
Mallison, H. 2010. The digital Plateosaurus II: An assessment of the range of motion of the limbs and vertebral column and of previous reconstructions using a digital skeletal mount. Acata Palaeontologica Polonica 55: 433-458.
Mannion, P. D., and Upchurch, P. 2010. Completeness metrics and the quality of the sauropodomorph fossil record through geological and historical time. Paleobiology 36:283-302.
Marsicano, C.A., Mancuso, A.C., Palma, R.M., and Krapovickas, V. 2010. Tetrapod tracks in a marginal lacustrine setting (Middle Triassic, Argentina): taphonomy and significance. Palaeogeography, Palaeoclimatology, Palaeoecology 291:388-399.
Martin, T., Sun, G., and Mosbrugger, V. 2010. Triassic-Jurassic biodiversity, ecosystems, and climate in the Junggar Basin, Xinjinag, northwest China. Palaeobiodiveristy and Palaeoenvironments 90:171-173.
Martinelli, A. G. 2010. On the postcanine dentition of Pascualgnathus polanskii Bonaparte (Cynodontia, Traversodontidae) from the Middle Triassic of Argentina. Geobios 43:629–638.
Mitchell, J. S., Heckert, A. B., and H.-D. Sues. 2010. Grooves to tubes: evolution of the venom delivery system in a Late Triassic “reptile”. Naturwissenschaften 97:1117-1121.
Modesto, S. P., and Botha-Brink, J. 2010. A burrow cast with Lystrosaurus skeletal remains from the Lower Triassic of South Africa. Palaios 25: 274-281.
Modesto, S. P., Scott, D. M., Botha-Brink, J, and Reisz, R. R. 2010. A new and unusual procolophonid parareptile from the Lower Triassic Katberg Formation of South Africa. Journal of Vertebrate Paleontology 30: 715-723.
Mukherjee, D., Ray, S., and Sengupta, D. P. 2010. Preliminary observations on the bone microstucture, growth patterns, and life habits of some Triassic temnospondyls from India. Journal of Vertebrate Paleontology 30: 78-93.
Nesbitt, S. J., and D. W. E. Hone. 2010. An external mandibular fenestra and other archosauriform character states in basal pterosaurs. Palaeodiversity 3: 225–233.
Nesbitt, S. J., Sidor, C. A., Irmis, R. B., Angielcyzk, K. D., Smith, R. M. H., and Tsuji, L. A. 2010. Ecologically distinct dinosaurian sister group shows early diversification of Ornithodira. Nature 464: 95-98.
Nicolas, M., and Rubidge, B. S. 2010. Changes in Permo-Triassic terrestrial tetrapod ecological representation in the Beaufort Group (Karoo Supergroup) of South Africa. Lethaia 43: 45-59.
Novikov, I. V. 2010. New data on Trematosauroid Labyrinthodonts of Eastern Europe: 2. Trematosaurus galae sp. nov.: cranial morphology. Paleontological Journal 44: 457-467.
de Oliveira, T. V., Sores, M. B., and Schultz, C. L. 2010. Trucidocynodon riograndensis gen. nov. et sp. nov. (Eucynodontia), a new cynodont from the Brazilian Upper Triassic (Santa Maria Formation). Zootaxa 2382, 71pp.
Osi, A. 2010: Feeding-related characters in basal pterosaurs: implications for jaw mechanism, dental function and diet. Lethaia, DOI: 10.1111/j.1502-3931.2010.00230.x.
Padian, K., Li, C., and Pchelnikova, J. 2010. The trackmaker of Apatopus (Late Triassic, North America): Implications for the evolution of archosaur stance and gait. Palaeontology 53: 175-189.
Parker, W. G., and Martz, J. W. 2010. Using positional homology in aetosaur (Archosauria: Pseudosuchia) osteoderms to evaluate the taxonomic status of Lucasuchus hunti. Journal of Vertebrate Paleontology 30: 1100-1108.
Piechowski, R., and Dzik, J. 2010. The axial skeleton of Silesaurus opolensis. Journal of Vertebrate Paleontology 30: 1127-1141.
Ray, S., Bandyopadhyay, S., and R. Appana. 2010. Bone Histology of a Kannemeyeriid Dicynodont Wadiasaurus: Palaeobiological Implications; pp. 73-89 in S. Bandyopadhyay (ed.), New Aspects of Mesozoic Biodiversity, Lecture Notes in Earth Sciences 132, DOI 10.1007/978-3-642-10311-7
Renesto, S. 2010. A new specimen of Nothosaurus from the Latest Anisian (Middle Triassic) Besano Formation (Grenzbitumenzone) of Italy: Rivista Italiana di Paleontologia e Stratigrafia 116: 245-260.
Renesto, S., Spielmann, J. A., Lucas, S. G., and Spagnoli, G. T. 2010. The taxonomy and paleobiology of the Late Triassic (Carnian-Norian: Adamanian-Apachean) drepanosaurs (Diapsida: Archosauromorpha: Drepanosauromorpha). New Mexico Museum of Natural History and Science Bulletin 46:1-81.
Rieppel, O., Jiang, D.-Y., Fraser, N. C., Hao, W.-C., Motani, R., Sun, Y.-L., and Sun, Z.-Y. 2010. Tanystropheus cf. T. longobardicus from the Early Late Triassic of Guizhou Province, Southwestern China. Journal of Vertebrate Paleontology 30: 1082-1089.
Rowe, T. B., Sues, H.-D., and R. Reisz. 2010. Dispersal and diversity in the earliest North American sauropodomorph dinosaurs, with a description of a new taxon. Proceedings of the Royal Society B, First Cite. doi:10.1098/rspb.2010.1867
Saila, L. K. 2010. Osteology of Leptopleuron lacertinum Owen, a procolophonoid parareptile from the Upper Triassic of Scotland, with remarks on ontogeny, ecology and affinities. Earth and Environmental Science Transactions of the Royal Society of Edinburgh, 101, 1–25.
Sanchez, S., Germain, D., De Ricqles, A., Abourachid, A., Goussard, F. and Tafforeau, P. 2010. Limb-bone histology of temnospondyls: implications for understanding the diversification of palaeoecologies and patterns of locomotion of Permo-Triassic tetrapods. Journal of Evolutionary Biology, early online. doi:10.1111/j.1420-9101.2010.02081.x
Santucci, V. L., and Kirkland, J. I. 2010. An overview of National Park Service Paleontological Resources from the Parks and Mounuments in Utah; pp. 589-623 in Sprinkel, D. A,. Chidsey, T. C., and Anderson, P. B. (eds.), Geology of Utah’s Parks and Monuments, Utah Geological Association Publication 28.
Scheyer, T. M. 2010. New interpretation of the postcranial skeleton and overall body shape of the placodont Cymodus hildegradis Peyer, 1931 (Reptilia, Sauropterygia). Palaentologia Electronica 13.2.15A.
Schoch, R. R., Voigt, S., and Buchwitz, M. 2010. A chroniosuchid from the Triassic of Kyrgyzstan and analysis of chroniosuchian relationships. Zoological Journal of the Linnean Society 160:515-530.
Schoch, R. R., Nesbitt, S., Müller, J., Lucas, S. G., and Boy, J. A., 2010. The reptile assemblage from the Moenkopi Formation (Middle Triassic) of New Mexico. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 255: 345-369.
Spielmann, J. A., and Lucas, S. G. 2010. Typothorax coccinarum (Archosauria: Stagonolepididae) from the Upper Triassic (Revueltian) Petrified Forest Formation, El Puertocito, Canon del Cobre, Rio Arriba County, New Mexico. New Mexico Museum of Natural History and Science Bulletin 49: 221-229.
Stocker, M. R. 2010. A new taxon of phytosaur (Archosauria: Pseudosuchia) from the Late Triassic (Norian) Sonsela Member (Chinle Formation) in Arizona, and a critical reevaluation of Leptosuchus Case, 1922. Palaeontology 53: 997-1022.
Sues, H.-D., and N. C. Fraser. 2010. Triassic life on land: The Great Transition. Columbia University Press, New York, 229p.
Sues, H.-D., and Hopson, J. A. 2010. Anatomy and phylogenetic relationships of Boreogomphodon jeffersoni (Cynodontia: Gomphodontia) from the Upper Triassic of Virginia. Journal of Vertebrate Paleontology 30: 1202-1220.
Sulej, T. 2010. The skull of an early Late Triassic aetosaur and the evolution of the stagonolepidid archosaurian reptiles. Zoological Journal of the Linnean Society 158:860-881.
Sullivan, C. 2010. The role of the calcaneal 'heel' as a propulsive lever in basal archosaurs and extant monitor lizards. Journal of Vertebrate Paleontology 30: 1422-1432.
Tanimoto, M., Utsunomiya, S., and Fujimoto, T. 2010. Osteichthyan teeth from the Early Triassic Taho Formation of Ehime Prefecture, Southwest Japan. Konseki 33: 49-52.
Tintori, A., Sun, Z.-Y., Lombardo, C., Jiang, D.-Y., Sun, Y.-L., and Hao, W.-C., 2010. A new basal neopterygian from the Middle Triassic of Luoping County (South China). Rivista Italiana di Paleontologia e Stratigrafia 116 (2).
Tourania, A., Benaouissa, N.,Gand, G., Bourquinc, S., Jalil, N.-E., Broutind,J., Battail, B., Germaine, D., Khaldounea, F., Soumaya, S., Steyere, J. S., and R. . 2010. Evidence of an Early Triassic age (Olenekian) in Argana Basin (High Atlas, Morocco) based on new chirotherioidtraces. Comptes Rendus Palevol, early online.
Trotteyn, M. J. and J. A. Haro. 2010. The braincase of a specimen of Proterochampsa Reig (Archosauriformes: Proterochampsidae) from the Late Triassic of Argentina. Paläontologische Zeitschrift. Published on-line May 11 2010. DOI 10.1007/s12542-010-0068-7
Witzmann, F., Scholz, H., Mueller, J., and N. Kardjilov. 2010. Sculpture and vascularization of dermal bones, and the implications for the physiology of basal tetrapods. Zoological Journal of the Linnean Society 160:302-340.
Zhao, L.-J., Sato, T., Liu, J., Li, C., and X.-C. Wu. 2010. A new skeleton of Miodentosaurus brevis (Diapsida:Thalattosauria) with a further study of the taxon. Vertebrata PalAsiatica 48:1-10.
Snow on the Painted Desert
It makes it a bit hard to prospect for fossils, but I always find the Painted Desert to be even more beautiful under a blanket of snow. People are often generally surprised to hear that it snows in Arizona, but the entire state isn't like Phoenix.
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| photo courtesy of Dave Velk |
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