Not Triassic but sill extremely significant for work on Triassic archosauromorphs as Youngina is often used as an outgroup for phylogenetic studies of this clade. Great new information, extremely cool, and of course open access!
Gardner, N. M., Holliday, C. M., anf F. R. O'Keefe. 2010. The braincase of Youngina capensis (Reptilia: Diapsida): new insights from high-resolution CT scanning of the holotype. Palaeontologia Electronica 13.3.19A.
Abstract - Detailed descriptions of braincase anatomy in early diapsid reptiles have been historically rare given the difficulty of accessing this deep portion of the skull, because of poor preservation of the fossils or the inability to remove the surrounding skull roof. Previous descriptions of the braincase of Youngina capensis, a derived stem-diapsid reptile from the Late Permian (250 MYA) of South Africa, have relied on only partially preserved fossils. High resolution X-ray computed tomography (HRXCT) scanning, a new advance in biomedical sciences, has allowed us to examine the reasonably complete braincase of the holotype specimen of Youngina capensis for the first time by digitally peering through the sandstone matrix that filled the skull postmortem. We present the first detailed 3D visualizations of the braincase and the vestibular system in a Permian diapsid reptile. This new anatomical description is of great comparative and phylogenetic relevance to the study of the structure, function and evolution of the reptilian head.
Free Access to the Journal Palaeobiodiversity and Palaeoenvironments in November 2010
For the month of November, Springer is offering open access to articles in the journal Palaeobiodiversity and Palaeoenvironments. Recent artiles in this journal include the special issue on the "Triassic-Jurassic biodiversity, ecosystems, and climate in the Junggar Basin, Xinjiang, Northwest China".
http://www.springer.com/earth+sciences+and+geography/journal/12549
http://www.springer.com/earth+sciences+and+geography/journal/12549
Holy Lungfish! A Monster from the Cretaceous of North America
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| photo Kenshu Shimada |
Morphological Diversity and Biogeography of Procolophonids
Cisneros, J. C., and M. Ruta. 2010. Morphological diversity and biogeography of procolophonids (Amniota: Parareptilia). Journal of Systematic Paleontology 8:607-625. DOI: 10.1080/14772019.2010.491986.
Abstract - A recent phylogenetic analysis of procolophonid parareptiles is used as the basis for a study of morphological diversity (disparity) in these amniotes. Disparity values are compared in three groups of procolophonids (a paraphyletic series of basal taxa and two monophyletic sister groups: procolophonines and leptopleuronines), two ecophenotypic assemblages (one based upon inferred diet - non high-fibre versus high-fibre species; the other based upon cranial sculpture - non horned versus horned species), and two temporal assemblages (Lower Triassic versus Middle and Upper Triassic). The mean disparity values are comparable in the case of temporal and ecophenotypic assemblages. High-fibre species are marginally less disparate than non high-fibre species. The combined Middle and Upper Triassic species are slightly less disparate than Lower Triassic species. Finally, horned species are only slightly more disparate than non-horned species. The paraphyletic series of basal taxa and the leptopleuronines show similar disparity values, marginally higher than those for procolophonines. Phylogenetic analysis is also used to reconstruct the biogeographical history of procolophonids. Both ancestral area analysis and dispersal-vicariance analysis show that South Africa was the most likely ancestral area for procolophonids as a whole. North China - either as a single area or in combination with Russia or South Africa - was the most likely ancestral area for the leptopleuronine-procolophonine clade.
Abstract - A recent phylogenetic analysis of procolophonid parareptiles is used as the basis for a study of morphological diversity (disparity) in these amniotes. Disparity values are compared in three groups of procolophonids (a paraphyletic series of basal taxa and two monophyletic sister groups: procolophonines and leptopleuronines), two ecophenotypic assemblages (one based upon inferred diet - non high-fibre versus high-fibre species; the other based upon cranial sculpture - non horned versus horned species), and two temporal assemblages (Lower Triassic versus Middle and Upper Triassic). The mean disparity values are comparable in the case of temporal and ecophenotypic assemblages. High-fibre species are marginally less disparate than non high-fibre species. The combined Middle and Upper Triassic species are slightly less disparate than Lower Triassic species. Finally, horned species are only slightly more disparate than non-horned species. The paraphyletic series of basal taxa and the leptopleuronines show similar disparity values, marginally higher than those for procolophonines. Phylogenetic analysis is also used to reconstruct the biogeographical history of procolophonids. Both ancestral area analysis and dispersal-vicariance analysis show that South Africa was the most likely ancestral area for procolophonids as a whole. North China - either as a single area or in combination with Russia or South Africa - was the most likely ancestral area for the leptopleuronine-procolophonine clade.
New Species of the Late Triassic Venomous Archosauriform Uatchitodon
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, online first. DOI 10.1007/s00114-010-0729-0
Abstract - Venom delivery systems occur in a wide range of extant and fossil vertebrates and are primarily based on oral adaptations. Teeth range from unmodified (Komodo dragons) to highly specialized fangs similar to hypodermic needles (protero- and solenoglyphous snakes). Developmental biologists have documented evidence for an infolding pathway of fang evolution, where the groove folds over to create the more derived condition. However, the oldest known members of venomous clades retain the same condition as their extant relatives, resulting in no fossil evidence for the transition. Based on a comparison of previously known specimens with newly discovered teeth from North Carolina, we describe a new species of the Late Triassic archosauriform Uatchitodon and provide detailed analyses that provide evidence for both venom conduction and document a complete structural series from shallow grooves to fully enclosed tubular canals. While known only from teeth, Uatchitodon is highly diagnostic in possessing compound serrations and for having two venom canals on each tooth in the dentition. Further, although not a snake, Uatchitodon sheds light on the evolutionary trajectory of venom delivery systems in amniotes and provide solid evidence for venom conduction in archosaur-line diapsids.
Supplemental data available here.
Abstract - Venom delivery systems occur in a wide range of extant and fossil vertebrates and are primarily based on oral adaptations. Teeth range from unmodified (Komodo dragons) to highly specialized fangs similar to hypodermic needles (protero- and solenoglyphous snakes). Developmental biologists have documented evidence for an infolding pathway of fang evolution, where the groove folds over to create the more derived condition. However, the oldest known members of venomous clades retain the same condition as their extant relatives, resulting in no fossil evidence for the transition. Based on a comparison of previously known specimens with newly discovered teeth from North Carolina, we describe a new species of the Late Triassic archosauriform Uatchitodon and provide detailed analyses that provide evidence for both venom conduction and document a complete structural series from shallow grooves to fully enclosed tubular canals. While known only from teeth, Uatchitodon is highly diagnostic in possessing compound serrations and for having two venom canals on each tooth in the dentition. Further, although not a snake, Uatchitodon sheds light on the evolutionary trajectory of venom delivery systems in amniotes and provide solid evidence for venom conduction in archosaur-line diapsids.
Supplemental data available here.
Madygenerpeton pustulatus, A New Chroniosuchid Reptilomorph from the Triassic of Kyrgyzstan
Schoch, R. R., Voigt, S., and M. Buchwitz. 2010. A chroniosuchid from the Triassic of Kyrgyzstan and analysis of chroniosuchian relationships. Zoological Journal of the Linnean Society 160: 515–530. doi:10.1111/j.1096-3642.2009.00613.x
Abstract - A nearly complete skull and associated osteoderms from the Middle/Upper Triassic Madygen Formation of Kyrgyzstan are referred to a new chroniosuchid genus and species. The new taxon is characterized by a parabolic skull outline, pustular ornamentation, tabular-squamosal contact, marked postparietal embayments, and the lack of an antorbital fontanelle. The palate is only preserved in part, showing broad palatines and ectopterygoids. Presence of a preorbital fenestra and characteristic osteoderm morphology are synapomorphies shared with all other chroniosuchids. According to the phylogenetic analysis performed, the new chroniosuchid nests with Chroniosaurus, with which it shares the wide, transversely extended osteoderms and pustular ornamentation. The chroniosuchians are robustly supported as a natural group, but their position within the reptiliomorph (stem-amniote) clade is not adequately understood. Whereas the parasphenoid is similar to that of anthracosaurs, most other characters support a higher nesting of chroniosuchians within the stem-amniotes.
Abstract - A nearly complete skull and associated osteoderms from the Middle/Upper Triassic Madygen Formation of Kyrgyzstan are referred to a new chroniosuchid genus and species. The new taxon is characterized by a parabolic skull outline, pustular ornamentation, tabular-squamosal contact, marked postparietal embayments, and the lack of an antorbital fontanelle. The palate is only preserved in part, showing broad palatines and ectopterygoids. Presence of a preorbital fenestra and characteristic osteoderm morphology are synapomorphies shared with all other chroniosuchids. According to the phylogenetic analysis performed, the new chroniosuchid nests with Chroniosaurus, with which it shares the wide, transversely extended osteoderms and pustular ornamentation. The chroniosuchians are robustly supported as a natural group, but their position within the reptiliomorph (stem-amniote) clade is not adequately understood. Whereas the parasphenoid is similar to that of anthracosaurs, most other characters support a higher nesting of chroniosuchians within the stem-amniotes.
Upcoming Article on Massospondylus (Sauropodomorpha) Embryos from the Lower Jurassic of Africa
A bunch of news articles have come out over the last two days discussing an upcoming article in the Journal of Vertebrate Paleontology discussing details of embrionic remains of the Jurassic sauropodomorph Massospondylus.
At this time it is unclear how this paper will differ from the original find of Massospondylus embryos in 2005.
You can check out two of the new stories (including photos) here and here.
At this time it is unclear how this paper will differ from the original find of Massospondylus embryos in 2005.
You can check out two of the new stories (including photos) here and here.
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| from http://www.msnbc.msn.com/id/40133043/ns/technology_and_science-science/ |
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.
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