Abstract - The holotype of the large temnospondyl Calamops paludosus is the oldest known tetrapod fossil from the Triassic of the Newark basin in Pennsylvania. Although it is usually placed in Metoposauridae, its affinities have remained unknown since its original description because the unique specimen had never been prepared. Preparation and casting of the specimen, which comprises three pieces of a left mandibular ramus, now permits detailed anatomical description of the jaw and assessment of its affinities. Calamops paludosus is a valid taxon of trematosauroid temnospondyls that can be diagnosed by several autapomorphies. It represents one of the geologically youngest known records of long-snouted trematosaurs and the first record of these temnospondyls from the Late Triassic of North America.
Showing posts with label Newark Supergroup. Show all posts
Showing posts with label Newark Supergroup. Show all posts
New Information on the Temnospondyl Calamops paludosus from the Upper Triassic of Pennsylvania
Sues, H.-D., and R. R. Schoch. 2013. Anatomy and phylogenetic relationships of Calamops paludosus (Temnospondyli, Stereospondyli) from the Triassic of the Newark Basin, Pennsylvania. Journal of Vertebrate Paleontology 33:1061-1070. DOI:10.1080/02724634.2013.759120
New Data Linking the End-Triassic Extinction with the Central Atlantic Magmatic Province.
Out today in Science Express. This study also provides support for the accuracy of the astrochronologically tuned time scale proposed for the Late Triassic Newark Supergroup sequence.
Blackburn, T. J., Olsen, P. E., Bowring, S. A., McLean, N. M., Kent, D. V., Puffer, J., McHone, G., Rasbury, E. T., and M. Et-Touhami. 2013. Zircon U-Pb Geochronology Links the End-Triassic Extinction with the Central Atlantic Magmatic Province. Science Express. http://www.sciencemag.org/content/early/recent / 21 March 2013 / Page 1/ 10.1126/science.1234204
Abstract - The end-Triassic extinction is characterized by major losses in both terrestrial and marine diversity, setting the stage for dinosaurs to dominate Earth for the next 136 million years. Despite the approximate coincidence between this extinction and flood basalt volcanism, existing geochronologic dates have insufficient resolution to confirm eruptive rates required to induce major climate perturbations. Here we present new zircon U-Pb geochronologic constraints on the age and duration of flood basalt volcanism within the Central Atlantic Magmatic Province. This chronology demonstrates synchroneity between the earliest volcanism and extinction, tests and corroborates the existing astrochronologic time scale, and shows that the release of magma and associated atmospheric flux occurred in four pulses over ~600,000 years, indicating expansive volcanism even as the biologic recovery was under way.
Blackburn, T. J., Olsen, P. E., Bowring, S. A., McLean, N. M., Kent, D. V., Puffer, J., McHone, G., Rasbury, E. T., and M. Et-Touhami. 2013. Zircon U-Pb Geochronology Links the End-Triassic Extinction with the Central Atlantic Magmatic Province. Science Express. http://www.sciencemag.org/content/early/recent / 21 March 2013 / Page 1/ 10.1126/science.1234204
Abstract - The end-Triassic extinction is characterized by major losses in both terrestrial and marine diversity, setting the stage for dinosaurs to dominate Earth for the next 136 million years. Despite the approximate coincidence between this extinction and flood basalt volcanism, existing geochronologic dates have insufficient resolution to confirm eruptive rates required to induce major climate perturbations. Here we present new zircon U-Pb geochronologic constraints on the age and duration of flood basalt volcanism within the Central Atlantic Magmatic Province. This chronology demonstrates synchroneity between the earliest volcanism and extinction, tests and corroborates the existing astrochronologic time scale, and shows that the release of magma and associated atmospheric flux occurred in four pulses over ~600,000 years, indicating expansive volcanism even as the biologic recovery was under way.
New Data on Small Theropod Footprints from Massachusetts
Dalman. S. G. 2012. New Data on Small Theropod Footprints from the Early Jurassic (Hettangian) Hartford Basin of Massachusetts, United States. Bulletin of the Peabody Museum of Natural History 53:333-353. doi:http://www.bioone.org/doi/abs/10.3374/014.053.0201
Abstract - A Portland Formation Lower Jurassic (Hettangian) dinosaur tracksite in Granby, Massachusetts, USA, has yielded a diverse dinosaur footprint assemblage. The tracksite preserves 140 theropod dinosaur footprints, ranging in length from 15 to 35 cm; the ichnofauna includes Anchisauripus, Eubrontes, Grallator and other extremely small theropod dinosaur footprints. The small tracks are compared with similar ichnites from the Lower Jurassic of western North America and central Poland. The small theropod footprints, which are described in detail, show some resemblance to the poorly known ichnogenus Stenonyx (Lull, 1904), which is considered an invalid ichnotaxon by many other workers. The footprints exhibit a distinct morphology of the metatarsophalangeal area, suggesting that these small ichnites are closely related to Kayentapus and Grallator. These small tracks are the first reported from the Hartford Basin of Granby, Massachusetts.
Abstract - A Portland Formation Lower Jurassic (Hettangian) dinosaur tracksite in Granby, Massachusetts, USA, has yielded a diverse dinosaur footprint assemblage. The tracksite preserves 140 theropod dinosaur footprints, ranging in length from 15 to 35 cm; the ichnofauna includes Anchisauripus, Eubrontes, Grallator and other extremely small theropod dinosaur footprints. The small tracks are compared with similar ichnites from the Lower Jurassic of western North America and central Poland. The small theropod footprints, which are described in detail, show some resemblance to the poorly known ichnogenus Stenonyx (Lull, 1904), which is considered an invalid ichnotaxon by many other workers. The footprints exhibit a distinct morphology of the metatarsophalangeal area, suggesting that these small ichnites are closely related to Kayentapus and Grallator. These small tracks are the first reported from the Hartford Basin of Granby, Massachusetts.
Dentition and Tooth Replacement in an Upper Triassic Traversodont Cynodont from the Eastern United States
Liu, J., and H.-D. Sues. 2010. Dentition and tooth replacement of Boreogomphodon (Cynodontia: Traversodontidae) from the Upper Triassic of North Carolina, USA. Vertebrata PalAsiatica 48:169-184.
Abstract - The teeth of new specimens of the traversodontid cynodont Boreogomphodon from the Upper Triassic of North Carolina are described. Based on dental features, especially the postcanine morphology, the North Carolina specimens are tentatively referred to Boreogomphodon jeffersoni, although their lower gomphodont postcanines typically have two rather than three cusps on the anterior transverse ridge. Based on the tooth size, direct replacement on all available specimens, the gomphodont teeth were shed anteriorly and added posteriorly. Only one generation of gomphodont teeth, at least one and possibly two generations of sectorial postcanines were present.
Abstract - The teeth of new specimens of the traversodontid cynodont Boreogomphodon from the Upper Triassic of North Carolina are described. Based on dental features, especially the postcanine morphology, the North Carolina specimens are tentatively referred to Boreogomphodon jeffersoni, although their lower gomphodont postcanines typically have two rather than three cusps on the anterior transverse ridge. Based on the tooth size, direct replacement on all available specimens, the gomphodont teeth were shed anteriorly and added posteriorly. Only one generation of gomphodont teeth, at least one and possibly two generations of sectorial postcanines were present.
New Information of the Cynodont Boreogomphodon jeffersoni from the Newark Supergroup
One of the bigger Triassic mysteries is why cynodonts are so common in the Newark Supergroup, while completely lacking in the presumably contemporaneous Chinle Formation (despite what you saw on 'Walking With Dinosaurs').
Sues, H.-D., and J. A. Hopson. 2010. Anatomy and phylogenetic relationships of Boreogomphodon jeffersoni (Cynodontia: Gomphodontia) from the Upper Triassic of Virginia. Journal of Vertebrate Paleontology 30:1202 – 1220. DOI: 10.1080/02724634.2010.483545
Abstract - We present a detailed account on the skeletal structure of the traversodont cynodont Boreogomphodon jeffersoni on the basis of a considerable quantity of excellently preserved craniodental remains and several referred postcranial bones from the Tomahawk Creek Member of the Vinita Formation (Upper Triassic: Carnian) of the Richmond basin (Newark Supergroup) in eastern Virginia. The small size, proportionately short snout and mandible, low number of molariform postcanine teeth, and presence of up to three sectorial postcanines all indicate that most of the specimens recovered to date represent immature individuals. The superbly preserved dental material permits detailed inferences regarding tooth replacement and dental function during ontogeny. Boreogomphodon differs from other known traversodont cynodonts primarily in the possession of lower molariform postcanine teeth with three rather than two anterior cusps in all but the smallest specimens, zygomatic arches that are bowed laterally at about mid-length, and pronounced, irregular sculpturing on the dorsal surface of the snout. Plesiomorphic features of traversodont cynodonts retained by Boreogomphodon include the position of the paracanine fossa anterolingual to the upper canine as well as the presence of a distinct central cusp and a posterior cingulum on the upper molariform postcanines. Phylogenetic analysis suggests the existence of a clade comprising Boreogomphodon plus two other taxa (Arctotraversodon and Nanogomphodon) in the Northern Hemisphere that is the sister group to most other known Middle and Late Triassic traversodonts from Gondwana.
Sues, H.-D., and J. A. Hopson. 2010. Anatomy and phylogenetic relationships of Boreogomphodon jeffersoni (Cynodontia: Gomphodontia) from the Upper Triassic of Virginia. Journal of Vertebrate Paleontology 30:1202 – 1220. DOI: 10.1080/02724634.2010.483545
Abstract - We present a detailed account on the skeletal structure of the traversodont cynodont Boreogomphodon jeffersoni on the basis of a considerable quantity of excellently preserved craniodental remains and several referred postcranial bones from the Tomahawk Creek Member of the Vinita Formation (Upper Triassic: Carnian) of the Richmond basin (Newark Supergroup) in eastern Virginia. The small size, proportionately short snout and mandible, low number of molariform postcanine teeth, and presence of up to three sectorial postcanines all indicate that most of the specimens recovered to date represent immature individuals. The superbly preserved dental material permits detailed inferences regarding tooth replacement and dental function during ontogeny. Boreogomphodon differs from other known traversodont cynodonts primarily in the possession of lower molariform postcanine teeth with three rather than two anterior cusps in all but the smallest specimens, zygomatic arches that are bowed laterally at about mid-length, and pronounced, irregular sculpturing on the dorsal surface of the snout. Plesiomorphic features of traversodont cynodonts retained by Boreogomphodon include the position of the paracanine fossa anterolingual to the upper canine as well as the presence of a distinct central cusp and a posterior cingulum on the upper molariform postcanines. Phylogenetic analysis suggests the existence of a clade comprising Boreogomphodon plus two other taxa (Arctotraversodon and Nanogomphodon) in the Northern Hemisphere that is the sister group to most other known Middle and Late Triassic traversodonts from Gondwana.
Incredible Triassic Site - Solite Quarry
Wow. I'd like to bring your attention to this recent post by Alton Dooley on the Virginia Museum of Natural History's blog "Updates From the Vertebrate Paleontology Lab". This quarry is famous for its exquisite preservation, especially of Late Triassic insects. Small "reptiles" such as Tanytrachelos, especially articulated ones, are extremely rare to unknown from the Chinle Formation due to the lack of strata with this type of preservation. In Petrified Forest National Park we get fine-grained shales that preserve mostly plant material (leaves, stems), as well as the occasional invertebrates (unionids, isolated insect wings, and our best find, a fresh water lobster!),; however, these layers are seemingly devoid of vertebrates (although I still try from time to time, something I like to call "playing the slot machine").
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