Chinleana has Reached Over 100,000 Visitors
Today the counter at the bottom of the main page went over 100,000 hits. I'd like to thank everyone who has visited Chinleana over the last couple of years. When I decided to start a blog featuring mainly Triassic paleontology, I wondered if I would have enough material to make it a couple of months. Two years and three months later I have been able to post an average of every three days and there seems to be no shortage of news of material to post or discuss. It absolutely amazes me how much Triassic related work is published each year and this is surely a tribute to the hard work of all of my Triassic colleagues and my readers. Thank you.
A New Paper That is Sure to Stir Up Some Debate
I'm not an expert on feathers so I can't offer an opinion but I'm sure lots of others will.
Dzik, J., Sulej, T., and G. Niedwiedzki. 2010. Possible link connecting reptilian scales with avian feathers from the early Late Jurassic of Kazakstan. Historical Biology 22: 394-402.
Abstract - Organic tissue of a recently found second specimen of feather-like Praeornis from the Karabastau Formation of the Great Karatau Range in southern Kazakstan, has a stable carbon isotope composition indicative of its animal affinity. Three-dimensional preservation of its robust carbonised shaft indicates original high contents of sclerotic organic matter, which makes the originally proposed interpretation of Praeornis as a keratinous integumental structure likely. The new specimen is similar to the holotype of Praeornis in the presence of three 'vanes' on a massive shaft not decreasing in width up to near its tip. Unlike it, the vanes are not subdivided into barbs and the pennate structure is expressed only in the distribution of organic-matter-rich rays. Similar continuous blades border the 'barbs' in the holotype, but the organic matter was removed from them by weathering. It is proposed that the three-vaned structure is a remnant of the ancestral location of scales along the dorsum and their original function in sexual display, similar to that proposed for the Late Triassic probable megalancosaurid Longisquama. Perhaps subsequent rotation around the shaft, in the course of evolution from an ancestral status similar to Praeornis towards the present aerodynamic and protective function of feathers, resulted in the tubular appearance of their buds.
Dzik, J., Sulej, T., and G. Niedwiedzki. 2010. Possible link connecting reptilian scales with avian feathers from the early Late Jurassic of Kazakstan. Historical Biology 22: 394-402.
Abstract - Organic tissue of a recently found second specimen of feather-like Praeornis from the Karabastau Formation of the Great Karatau Range in southern Kazakstan, has a stable carbon isotope composition indicative of its animal affinity. Three-dimensional preservation of its robust carbonised shaft indicates original high contents of sclerotic organic matter, which makes the originally proposed interpretation of Praeornis as a keratinous integumental structure likely. The new specimen is similar to the holotype of Praeornis in the presence of three 'vanes' on a massive shaft not decreasing in width up to near its tip. Unlike it, the vanes are not subdivided into barbs and the pennate structure is expressed only in the distribution of organic-matter-rich rays. Similar continuous blades border the 'barbs' in the holotype, but the organic matter was removed from them by weathering. It is proposed that the three-vaned structure is a remnant of the ancestral location of scales along the dorsum and their original function in sexual display, similar to that proposed for the Late Triassic probable megalancosaurid Longisquama. Perhaps subsequent rotation around the shaft, in the course of evolution from an ancestral status similar to Praeornis towards the present aerodynamic and protective function of feathers, resulted in the tubular appearance of their buds.
Time Now for a Pseudosuchian - Desmatosuchus spurensis by Jeff Martz
Based on the traffic I've been getting everyone has really been enjoying the critter reconstructions by Jeff Martz. The past few days have focused on the ornithidirans but I think it is time to journey over to the other archosaurian branch. Here is the aetosaur Desmatosuchus spurensis from the Late Triassic of the American southwest. If you really enjoy Jeff's work, please let him hear it.
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Plateosaurus engelhardti Reconstruction by Jeffrey Martz
This is the last sample in Jeff Martz's dinosauromorph series and by far one of the most striking reconstructions, especially the coloration. This is the sauropodomorph Plateosaurus from the Upper Triassic of Germany.
Lesothosaurus diagnosticus Reconstruction by Jeff Martz
Here is a colorful, feathered, and very mean version of the Jurassic basal ornithischian Lesothosaurus from South Africa. I think that this would make a great mascot for some college sports team.
Silesaurus opolensis Reconstruction by Jeff Martz
This is my favorite in Jeff's dinosauromorph series. The silesaurid dinosauriform Silesaurus from the Upper Triassic of Poland.
Marasuchus lilloensis Reconstruction by Jeffrey Martz
Continuing along on the new dinosauromorph series by Jeff Martz, here is a bluish version of the dinosauromorph Marasuchus from the Middle Triassic of Argentina.
Coelophysis bauri Reconstruction by Jeff Martz
A very colorful and fuzzy Coelophysis. Part of the new dinosauromorph series by Jeff Martz.
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| The neotheropod Coelophysis bauri from the Upper Triassic of New Mexico. |
Herrerasaurus ischigualastensis Reconstruction by Jeff Martz
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| The herrerasaurid Herrerasaurus ischigualastensis from the Upper Triassic of Argentina |
Tawa hallae Reconstruction by Jeff Martz
It has been awhile since I have featured some of Jeff Martz's Triassic critter artwork on this site. Since that time his work has gained much more recognition, including some kudos from his mom! He has posted some his more recent dinosauromorph material on his own site, but just in case you missed it I'll be reposting some of it here over the next few days.
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| The basal theropod Tawa hallae from the Upper Triassic Petrified Forest Member of the Chinle Formation in the Chama Basin of north-central New Mexico. |
Chinle Formation Scenes
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| The Petrified Forest/Owl Rock Member contact in the Little Painted Desert north of Winslow, Arizona |
Two New Papers on the Triassic/Jurassic Boundary
Kent, D. V., and E. Irving. 2010. Influence of inclination error in sedimentary rocks on the Triassic and Jurassic apparent pole wander path for North America and implications for Cordilleran tectonics. Journal Of Geophysical Research 115: B10103, doi:10.1029/2009JB007205
Abstract - Because of paleomagnetic inclination error (I error) in sedimentary rocks, we argue that previous estimates of Triassic and Jurassic paleolatitudes of the North American craton have generally been too low, the record being derived mostly from sedimentary rocks. Using results from all major cratons, we construct a new composite apparent pole wander (APW) path for Triassic through Paleogene based on 69 paleopoles ranging in age from 243 to 43 Ma. The poles are from igneous rocks and certain sedimentary formations corrected for I error brought into North American coordinates using plate tectonic reconstructions. Key features of the new APW path are a 25° northward progression from 230 to 190 Ma to high latitudes (off northernmost Siberia) where the pole lingers until 160 Ma, a jump to the Aleutians followed by a hook in western Alaska by ∼145 Ma that leads to the 130–60 Ma stillstand, after which the pole moves to its present position. As an example of the application of this new path we use paleomagnetic results to determine that southern Wrangellia and Stikinia (W/S), the two most westerly terranes in the Canadian Cordillera, lay 630 to 1650 km farther south than at present relative to the craton during the Late Triassic and Early Jurassic. This is consistent with an exotic Tethyan origin as paleontological and mantle geochemical evidences imply. During the Late Triassic through Early Cretaceous, W/S moved northward more slowly than the craton, implying oblique sinistral net convergence over this 130 Myr interval. This was followed by dextral shear in latest Cretaceous through Eocene.
Donohoo-Hurley, L. L., Geissman, J. W., and S. G. Lucas. 2010. Magnetostratigraphy of the uppermost Triassic and lowermost Jurassic Moenave Formation, western United States: Correlation with strata in the United Kingdom, Morocco, Turkey, Italy, and eastern United States. Geological Society of America Bulletin 122: 2005-2019; doi: 10.1130/B30136.1
Abstract - A composite magnetostratigraphy based on the magnetic polarity data from four sections of the uppermost Triassic and lowermost Jurassic Moenave Formation, Utah and Arizona, USA, can be correlated to the marine successions at Saint Audrie’s Bay (UK), Oyuklu, Turkey, and the Southern Alps, Italy, and to the nonmarine sections in Morocco, northern Africa, and the Newark Basin, eastern North America, all deposited across the Triassic–Jurassic boundary. Our proposed correlation provides a stratigraphic framework to tie Triassic–Jurassic sedimentation in the American Southwest to the marine UK, Turkey, and Italy sections, and to the Pangea rift history, including extrusive igneous rocks, preserved in Morocco and in the Newark Basin. The Moenave polarity record is characterized by mostly normal polarity, as is consistent with other polarity records across the Triassic–Jurassic boundary, and is interrupted by at least two well-defined reverse-polarity magnetozones. On the basis of available paleontologic information, we interpret the oldest well defined, reverse-polarity magnetozone, M2r of the Moenave Formation, to correlate with SA5n.2r or SA5n.3r of the Saint Audrie’s Bay record, H– of the Oyuklu record, BIT5n.1r of the Italcementi Quarry record, the oldest reverse magnetozone in sedimentary rocks in Morocco, and with reverse magnetozone E23r of the Newark Basin. The youngest reverse magnetozone of the Moenave Formation, M3r, is correlated to the latest Triassic magnetozones SA5n.5r of the Saint Audrie’s Bay record, J– of the Oyuklu record, and with the interval of reverse polarity in the “intermediate unit” of the Morocco record. Magnetostratigraphic correlations and marine biostratigraphic information support placement of the Triassic–Jurassic boundary in the middle to upper Whitmore Point Member of the Moenave Formation, the Lias Group of the Saint Audrie’s Bay section, the chert-rich limestone of the Oyuklu section, above the Zu Limestone in Italy, and in the central Atlantic magmatic province extrusive zone in the Morocco and the Newark records.
Abstract - Because of paleomagnetic inclination error (I error) in sedimentary rocks, we argue that previous estimates of Triassic and Jurassic paleolatitudes of the North American craton have generally been too low, the record being derived mostly from sedimentary rocks. Using results from all major cratons, we construct a new composite apparent pole wander (APW) path for Triassic through Paleogene based on 69 paleopoles ranging in age from 243 to 43 Ma. The poles are from igneous rocks and certain sedimentary formations corrected for I error brought into North American coordinates using plate tectonic reconstructions. Key features of the new APW path are a 25° northward progression from 230 to 190 Ma to high latitudes (off northernmost Siberia) where the pole lingers until 160 Ma, a jump to the Aleutians followed by a hook in western Alaska by ∼145 Ma that leads to the 130–60 Ma stillstand, after which the pole moves to its present position. As an example of the application of this new path we use paleomagnetic results to determine that southern Wrangellia and Stikinia (W/S), the two most westerly terranes in the Canadian Cordillera, lay 630 to 1650 km farther south than at present relative to the craton during the Late Triassic and Early Jurassic. This is consistent with an exotic Tethyan origin as paleontological and mantle geochemical evidences imply. During the Late Triassic through Early Cretaceous, W/S moved northward more slowly than the craton, implying oblique sinistral net convergence over this 130 Myr interval. This was followed by dextral shear in latest Cretaceous through Eocene.
Donohoo-Hurley, L. L., Geissman, J. W., and S. G. Lucas. 2010. Magnetostratigraphy of the uppermost Triassic and lowermost Jurassic Moenave Formation, western United States: Correlation with strata in the United Kingdom, Morocco, Turkey, Italy, and eastern United States. Geological Society of America Bulletin 122: 2005-2019; doi: 10.1130/B30136.1
Abstract - A composite magnetostratigraphy based on the magnetic polarity data from four sections of the uppermost Triassic and lowermost Jurassic Moenave Formation, Utah and Arizona, USA, can be correlated to the marine successions at Saint Audrie’s Bay (UK), Oyuklu, Turkey, and the Southern Alps, Italy, and to the nonmarine sections in Morocco, northern Africa, and the Newark Basin, eastern North America, all deposited across the Triassic–Jurassic boundary. Our proposed correlation provides a stratigraphic framework to tie Triassic–Jurassic sedimentation in the American Southwest to the marine UK, Turkey, and Italy sections, and to the Pangea rift history, including extrusive igneous rocks, preserved in Morocco and in the Newark Basin. The Moenave polarity record is characterized by mostly normal polarity, as is consistent with other polarity records across the Triassic–Jurassic boundary, and is interrupted by at least two well-defined reverse-polarity magnetozones. On the basis of available paleontologic information, we interpret the oldest well defined, reverse-polarity magnetozone, M2r of the Moenave Formation, to correlate with SA5n.2r or SA5n.3r of the Saint Audrie’s Bay record, H– of the Oyuklu record, BIT5n.1r of the Italcementi Quarry record, the oldest reverse magnetozone in sedimentary rocks in Morocco, and with reverse magnetozone E23r of the Newark Basin. The youngest reverse magnetozone of the Moenave Formation, M3r, is correlated to the latest Triassic magnetozones SA5n.5r of the Saint Audrie’s Bay record, J– of the Oyuklu record, and with the interval of reverse polarity in the “intermediate unit” of the Morocco record. Magnetostratigraphic correlations and marine biostratigraphic information support placement of the Triassic–Jurassic boundary in the middle to upper Whitmore Point Member of the Moenave Formation, the Lias Group of the Saint Audrie’s Bay section, the chert-rich limestone of the Oyuklu section, above the Zu Limestone in Italy, and in the central Atlantic magmatic province extrusive zone in the Morocco and the Newark records.
New Seed Ferns and Cycadophytes from the Middle Triassic of Germany
Kustatscher, E., and J. H. A. van Konijnenburg-van Cittert. 2010. Seed ferns and Cycadophytes from the Triassic Flora of Thale (Germany). Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 258: 195–217.
Abstract: This is the second paper on the Middle Triassic flora from Thale, dealing with the seed ferns and cycadophytes. Scytophyllum bergeri Bornemann is one of the common elements in the flora, in contrast to Sagenopteris sp. which is rare in the assemblage. However, it is the first evidence of Sagenopteris for the German Basin. The specimen described as ?Peltaspermum sp. is the only peltasperm ovuliferous organ known to date with attached ovule-bearing discs from the Middle Triassic of Europe. The cycad Apoldia tener (Compter 1883) Zijlstra et al. 2009 (formerly Sphenozamites tener Compter) is by far the most common fossil plant in the assemblage. Nilssonia cf. neuberi Stur ex Pott et al. is relatively rare. The genus Bjuvia is emended to accommodate more species of large entire leaves characterised by amphistomy and cycadalean stomatal morphology. This includes Bjuvia thalensis n. sp., which is a common element in the Thale flora but is unknown from elsewhere. Narrow, long entire leaves from the Middle and Upper Triassic of Europe have been described under the name Taeniopteris angustifolia Schenk, but have now been transferred to Taeniopteris kelberi n. sp. for nomenclatorial reasons. The macrosporophyll Dioonitocarpidium pennaeformis (Schenk) Ruhle von Lilienstern also occurs in the Thale flora. Two cycadalean leaf species (Apoldia tener and Bjuvia thalensis) from Thale flora sometimes have stomata with only two subsidiary cells instead of the usual 4-6, a feature that in gymnosperms occurs mainly in the Bennettitales.
Abstract: This is the second paper on the Middle Triassic flora from Thale, dealing with the seed ferns and cycadophytes. Scytophyllum bergeri Bornemann is one of the common elements in the flora, in contrast to Sagenopteris sp. which is rare in the assemblage. However, it is the first evidence of Sagenopteris for the German Basin. The specimen described as ?Peltaspermum sp. is the only peltasperm ovuliferous organ known to date with attached ovule-bearing discs from the Middle Triassic of Europe. The cycad Apoldia tener (Compter 1883) Zijlstra et al. 2009 (formerly Sphenozamites tener Compter) is by far the most common fossil plant in the assemblage. Nilssonia cf. neuberi Stur ex Pott et al. is relatively rare. The genus Bjuvia is emended to accommodate more species of large entire leaves characterised by amphistomy and cycadalean stomatal morphology. This includes Bjuvia thalensis n. sp., which is a common element in the Thale flora but is unknown from elsewhere. Narrow, long entire leaves from the Middle and Upper Triassic of Europe have been described under the name Taeniopteris angustifolia Schenk, but have now been transferred to Taeniopteris kelberi n. sp. for nomenclatorial reasons. The macrosporophyll Dioonitocarpidium pennaeformis (Schenk) Ruhle von Lilienstern also occurs in the Thale flora. Two cycadalean leaf species (Apoldia tener and Bjuvia thalensis) from Thale flora sometimes have stomata with only two subsidiary cells instead of the usual 4-6, a feature that in gymnosperms occurs mainly in the Bennettitales.
There are no Known Aetosaur Fossils from Madagascar!
I happened to click on the Wikipedia page for aetosaurs today. It is really shaping up as someone (or maybe a few people) is putting a lot of work into it. A few errors here and there and a couple taxonomic issues that will be addressed in some future publications (not all by me). However, the most glaring thing that caught my eye was location column for Desmatosuchus lists Madagascar (Isalo Group) as a unit containing fossils of Desmatosuchus. This is an occurrence I addressed in my M.S. thesis (Parker, 2003) and in my 2008 paper on the genus Desmatosuchus. It all stems from a problem in assigning a geological age to a fossil bearing horizon in the upper part of the Isalo II (part of the Isalo Group; Burmeister, 2000; Burmeister et al., 2006). This horizon includes fish fossils, as well as the remains of dinosaurs (sauropod, theropod) and other archosaurs, including teeth that are superficially similar to those of phytosaurs and a handful of osteoderms that belong to some type of pseudosuchian (see photo below from Burmeister, 2000).
Kurtis Burmeister first approached me in the late 1990s asking my opinion if these osteoderms could be from aetosaurs. I though the resemblance was purely superficial and despite he presence of an anterior bar and pitted ornamantation, the overall morphology and the lateral sutures were not typical of aetosaurs. In his thesis, he suggested they could be crocodyliform (pers. comm. from Mike Parrish), but preliminarily assigned them to the Aetosauria and noted a possible assignment to Desmatosuchus. This identification was based on showing the osteoderms to another aetosaur "expert" (Burmeister, pers. comm.).
A few years later I was approached again by another member of the research team who showed me the specimens again. This time I was with a small group of Triassic workers and coincidently we had a crocodyliform specialist with us as well. We all agreed that they were definitely not Desmatosuchus, not aetosaurian, and most likely a crocodyliform. In a subsequent publication (Burmeister et al., 2006) they are refered to an indeterminate crocodylotarsian (pseudosuchian) and the superficial resemblance to aetosaurs is discussed, although the authors note the osteoderms probably represent a goniopholidid crocodyliform and that the horizon is probably Early Jurassic in age. Parker (2008) argued that they were not aetosaurian and possessed characters found in mesoeucrocodylians.
Despite all of this ambiguity, these specimens were explicitly assigned to the aetosaur Dematosuchus haplocerus by Lucas et al. (2003) and used to provide an Adamanian (late Carnian) age for these beds. This identification and correlation was followed by Lucas (2010). Discussions with colleagues and the current Wikipedia entry for aetosaurs demonstrates that the identification of these specimens as aetosaurian is still misunderstood. For the 4th time (and hopefully the last) I would like to propose my opinion (based on two personal observations of the material and the figure above) that these are not aetosaur plates and most certainly not referable to Desmatosuchus. The ornament is too deep and irregular, furhtermore, if these are fragments of paramedian plates then the ornament would be too large. Finally, the sutural edges are completely different than anything found in aetosaurs, and certainly does not represent the "tongue-and-groove" articular surface found in desmatosuchines. There currently is no evidence for aetosaurs in the Isalo II and the age of the upper beds is most likely Jurassic (Burmeister et al., 2006; Parker, 2008) and not Adamanian in age (contra Lucas, 2010).
REFERENCES
Burmeister, K.C., 2000, Paleogeographic and biostratigraphic implications of new early Mesozoic terrestrial vertebrate fossils from the Poamay site: central Morondava Basin, Madagascar [M.A. thesis]: Santa Barbara, University of California, 109 p.
Burmeister, K.C., J.J. Flynn, J.M. Parrish, and A.R. Wyss. 2006. Paleogeographic and biostratigraphic implications of new early Mesozoic vertebrates from Poamay, central Morondava Basin, Madagascar. New Mexico Museum of Natural History Science Bulletin 37:457–475.
Lucas, S.G. 2010. The Triassic timescale based on nonmarine tetrapod biostratigraphy and biochronology; pp. 447-500 in Lucas, S. G. (ed.) The Triassic Timescale. Geological Society, London, Special Publications, 334.
Lucas, S.G., K.E. Zeigler, A.B. Heckert, and A.P. Hunt. 2003. Upper Triassic stratigraphy and biostratigraphy, Chama Basin, north-central New Mexico. New Mexico Museum of Natural History & Science Bulletin 24:15–39.
Parker, W.G. 2003. Description of a new specimen of Desmatosuchus haplocerus from the Late Triassic of Northern Arizona. M.S. thesis. Northern Arizona University, Flagstaff, AZ.
Parker, W.G. 2008. Description of new material of the aetosaur Desmatosuchus spurensis (Archosauria: Suchia) from the Chinle Formation of Arizona and a revision of the genus Desmatosuchus. PaleoBios 28:1-40.
Kurtis Burmeister first approached me in the late 1990s asking my opinion if these osteoderms could be from aetosaurs. I though the resemblance was purely superficial and despite he presence of an anterior bar and pitted ornamantation, the overall morphology and the lateral sutures were not typical of aetosaurs. In his thesis, he suggested they could be crocodyliform (pers. comm. from Mike Parrish), but preliminarily assigned them to the Aetosauria and noted a possible assignment to Desmatosuchus. This identification was based on showing the osteoderms to another aetosaur "expert" (Burmeister, pers. comm.).
A few years later I was approached again by another member of the research team who showed me the specimens again. This time I was with a small group of Triassic workers and coincidently we had a crocodyliform specialist with us as well. We all agreed that they were definitely not Desmatosuchus, not aetosaurian, and most likely a crocodyliform. In a subsequent publication (Burmeister et al., 2006) they are refered to an indeterminate crocodylotarsian (pseudosuchian) and the superficial resemblance to aetosaurs is discussed, although the authors note the osteoderms probably represent a goniopholidid crocodyliform and that the horizon is probably Early Jurassic in age. Parker (2008) argued that they were not aetosaurian and possessed characters found in mesoeucrocodylians.
Despite all of this ambiguity, these specimens were explicitly assigned to the aetosaur Dematosuchus haplocerus by Lucas et al. (2003) and used to provide an Adamanian (late Carnian) age for these beds. This identification and correlation was followed by Lucas (2010). Discussions with colleagues and the current Wikipedia entry for aetosaurs demonstrates that the identification of these specimens as aetosaurian is still misunderstood. For the 4th time (and hopefully the last) I would like to propose my opinion (based on two personal observations of the material and the figure above) that these are not aetosaur plates and most certainly not referable to Desmatosuchus. The ornament is too deep and irregular, furhtermore, if these are fragments of paramedian plates then the ornament would be too large. Finally, the sutural edges are completely different than anything found in aetosaurs, and certainly does not represent the "tongue-and-groove" articular surface found in desmatosuchines. There currently is no evidence for aetosaurs in the Isalo II and the age of the upper beds is most likely Jurassic (Burmeister et al., 2006; Parker, 2008) and not Adamanian in age (contra Lucas, 2010).
REFERENCES
Burmeister, K.C., 2000, Paleogeographic and biostratigraphic implications of new early Mesozoic terrestrial vertebrate fossils from the Poamay site: central Morondava Basin, Madagascar [M.A. thesis]: Santa Barbara, University of California, 109 p.
Burmeister, K.C., J.J. Flynn, J.M. Parrish, and A.R. Wyss. 2006. Paleogeographic and biostratigraphic implications of new early Mesozoic vertebrates from Poamay, central Morondava Basin, Madagascar. New Mexico Museum of Natural History Science Bulletin 37:457–475.
Lucas, S.G. 2010. The Triassic timescale based on nonmarine tetrapod biostratigraphy and biochronology; pp. 447-500 in Lucas, S. G. (ed.) The Triassic Timescale. Geological Society, London, Special Publications, 334.
Lucas, S.G., K.E. Zeigler, A.B. Heckert, and A.P. Hunt. 2003. Upper Triassic stratigraphy and biostratigraphy, Chama Basin, north-central New Mexico. New Mexico Museum of Natural History & Science Bulletin 24:15–39.
Parker, W.G. 2003. Description of a new specimen of Desmatosuchus haplocerus from the Late Triassic of Northern Arizona. M.S. thesis. Northern Arizona University, Flagstaff, AZ.
Parker, W.G. 2008. Description of new material of the aetosaur Desmatosuchus spurensis (Archosauria: Suchia) from the Chinle Formation of Arizona and a revision of the genus Desmatosuchus. PaleoBios 28:1-40.
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