tag:blogger.com,1999:blog-55192926170976280872019-03-24T00:04:22.030-07:00ChinleanaDiscussion of Late Triassic paleontology and other assorted topics.Bill Parkerhttp://www.blogger.com/profile/05941940882532354219noreply@blogger.comBlogger751125tag:blogger.com,1999:blog-5519292617097628087.post-73505110416155658962019-01-25T08:45:00.001-07:002019-01-25T08:45:08.216-07:00A New Placodont from the Late Triassic of China<b>Wang, W., Li, C., Scheyer, T. M., and Zhao, L. 2019. A new species of <i>Cyamodus</i> (Placodontia, Sauropterygia) from the early Late Triassic of south-west China. Journal of Systematic Palaeontology. <a href="https://www.tandfonline.com/doi/full/10.1080/14772019.2018.1535455">Link</a>.<br /><br />Abstract - </b>The Triassic eastern Tethyan faunas have continued to yield numerous specimens of marine reptile taxa in recent years. Nevertheless, compared with other sauropterygian clades, the diversity of placodonts in these faunas is low, and remains of this group are relatively rare in the fossil assemblages. Here, we report a new cyamodontoid specimen (ZMNH M8820) from the early Late Triassic of Guizhou, south-west China. This specimen is a nearly complete skeleton lacking only the forelimbs. It is distinct from other known Chinese placodonts as it features a large skull with remarkably enlarged supratemporal fenestrae and a small and less regularly arranged carapace. Interestingly, this new specimen resembles the European <i>Cyamodus</i> more than any Chinese cyamodontoid genera, particularly when considering the dentition and other cranial morphology. However, it differs from known <i>Cyamodus</i> species in some cranial features (e.g. epipterygoid fully ossified, posttemporal fenestra large, dentition derived) and the absence of a separate pelvic shield. Furthermore, based on an updated data matrix of placodonts, our phylogenetic results support the affinity of this new Chinese specimen with European <i>Cyamodus</i> species, and a new species, <i>Cyamodus orientalis sp. nov</i>., is erected here. This new material represents the first reported <i>Cyamodus</i> specimen in the world that preserves a three-dimensional skull with an associated postcranial skeleton and it extends the distribution of this genus into the early Carnian of the eastern Tethys. The existence of <i>Cyamodus</i>, a nearshore taxon, in south-west China at this time reveals greater similarity and more rapid intercommunication than previously known between western and eastern Tethyan vertebrate faunas, although the palaeobiogeographical origin and migration history of Cyamodontidae – and of other clades of placodont reptiles – are still obscure due to the scarcity of material from the northern and southern margins of the Palaeotethys.Bill Parkerhttp://www.blogger.com/profile/05941940882532354219noreply@blogger.com0tag:blogger.com,1999:blog-5519292617097628087.post-44527328128662392052019-01-25T08:40:00.004-07:002019-01-25T08:40:58.664-07:00Platypus-like Hupehsuchian from Early Triassic of China<b>Cheng, L., Motani, R., Jiang, D., Yan, C., Tintori, A. and O. Rieppel. 2019. Early Triassic marine reptile representing the oldest record of unusually small eyes in reptiles indicating non-visual prey detection. Scientific Reports 9, number 152. DOI: 10.1038/s41598-018-37754-6</b><div><b><br /></b></div><b>Abstract -</b> The end-Permian mass extinction (EPME) led to reorganization of marine predatory communities, through introduction of air-breathing top predators, such as marine reptiles. We report two new specimens of one such marine reptile, <i>Eretmorhipis carrolldongi</i>, from the Lower Triassic of Hubei, China, revealing superficial convergence with the modern duckbilled platypus (<i>Ornithorhynchus anatinus</i>), a monotreme mammal. Apparent similarities include exceptionally small eyes relative to the body, snout ending with crura with a large internasal space, housing a bone reminiscent of <i>os paradoxum</i>, a mysterious bone of platypus, and external grooves along the crura. The specimens also have a rigid body with triangular bony blades protruding from the back. The small eyes likely played reduced roles during foraging in this animal, as with extant amniotes (group containing mammals and reptiles) with similarly small eyes. Mechanoreceptors on the bill of the animal were probably used for prey detection instead. The specimens represent the oldest record of amniotes with extremely reduced visual capacity, utilizing non-visual cues for prey detection. The discovery reveals that the ecological diversity of marine predators was already high in the late Early Triassic, and challenges the traditional view that the ecological diversification of marine reptiles was delayed following the EPME.Bill Parkerhttp://www.blogger.com/profile/05941940882532354219noreply@blogger.com0tag:blogger.com,1999:blog-5519292617097628087.post-23132001860993537832019-01-18T06:00:00.000-07:002019-01-18T06:00:02.630-07:00Histological Evidence of Trauma in Dicynodont Tusks<b>Whitney, M. R., Ting Tse, Y., and C. A. Sidor. 2019. Histological evidence of trauma in tusks of southern African dicynodonts. Palaeontologia Africana 53: 75-80. <a href="http://wiredspace.wits.ac.za/handle/10539/26243">PDF</a>.<br /><br />Abstract -</b> Dicynodonts were a clade of globally-distributed therapsids known for their abundance in the fossil record and for surviving the Permo-Triassic mass extinction. The group had distinctive dental adaptations including a beak and, in many species, paired maxillary tusks. The function of these tusks has long been of interest, yet remains poorly understood.We report here on two instances of unusual morphology in tusk dentine from specimens of: 1) <i>Lystrosaurus</i> from the Karoo Basin of South Africa and, 2) an unidentified dicynodontoid from the Luangwa Basin of Zambia. In both, the cross-sectional shape of the tusk root is lobed and infolded, which histological features suggest is a result of abnormal dentine deposition. We infer that this abnormal morphology is likely the consequence of trauma given its reparative nature and structural similarities to trauma-related morphologies reported in the tusks of modern elephants. This study demonstrates that histological sampling of dicynodont tusks can shed light on the biology of this important clade of therapsids.Bill Parkerhttp://www.blogger.com/profile/05941940882532354219noreply@blogger.com0tag:blogger.com,1999:blog-5519292617097628087.post-53659325307305131712019-01-17T10:53:00.000-07:002019-01-17T10:53:27.594-07:00Examining Functional Convergence Between Triassic Phytosaurs and Slender-Snouted Crocodylians<div>A new preprint in PeerJ.</div><b><div><b><br /></b></div>Lemanis R., Jones A.S., Butler R.J., Anderson P.S.L., and E.J. Rayfield. 2019. Comparative biomechanical analysis demonstrates functional convergence between slender-snouted crocodilians and phytosaurs. PeerJ Preprints 7:e27476v1<a href="https://doi.org/10.7287/peerj.preprints.27476v1">https://doi.org/10.7287/peerj.preprints.27476v1</a></b><div><b><br /></b></div><b>Abstract - </b>Morphological similarities between the extinct Triassic archosauriform clade Phytosauria and extant crocodilians have formed the basis of long-proposed hypotheses of evolutionary convergence. These hypotheses have informed the reconstructions of phytosaur ecology and biology, including feeding preferences, body mass, soft tissue systems, mating behaviours, and environmental preferences. However, phytosaurs possess numerous cranial apomorphies that distinguish them from modern crocodilians and potentially limit ecomorphological comparisons. Here, we present the first computational mechanical comparison of phytosaur cranial strength to several extant crocodilian taxa using two biomechanical approaches: beam theory and finite element analysis. We demonstrate mechanical convergence between the slender-snouted phytosaur <i>Ebrachosuchus neukami</i> and modern slender-snouted crocodilians. We provide evidence that the phytosaurian premaxillary palate is functionally equivalent to the crocodilian secondary palate. The premaxillary palate is associated with greater resistance to biting induced stress, lower strain energy, higher resistance to bending and torsion, as well as increased performance under tension. In all tests, <i>Ebrachosuchus</i> performed worse than all tested crocodilians, showing higher stress under equivalent loading conditions. These findings have implications for the proposed feeding ecology of slender-snouted phytosaurs and corroborate previous broad assessments of phytosaur ecology based on morphological comparisons to crocodilians; however, we urge caution in overextending those assessments given the current paucity of comparative functional data.Bill Parkerhttp://www.blogger.com/profile/05941940882532354219noreply@blogger.com0tag:blogger.com,1999:blog-5519292617097628087.post-51461063403929622472019-01-15T13:51:00.002-07:002019-01-15T13:51:49.396-07:00Why are Temnospondyl Skulls Bumpy?<a href="https://bryangee.weebly.com/blog/bumps-and-lumps-a-primer-on-temnospondyl-ornamentation">Today</a> Bryan Gee at Temno Talk Blog discusses and evaluates the various hypotheses of why temnospondyl skulls (and other bones) have heavily ornamented, irregular surfaces.<br /><br />If you missed the link <a href="https://bryangee.weebly.com/blog/bumps-and-lumps-a-primer-on-temnospondyl-ornamentation">here it is again</a>.Bill Parkerhttp://www.blogger.com/profile/05941940882532354219noreply@blogger.com0tag:blogger.com,1999:blog-5519292617097628087.post-4228032919623170622019-01-10T21:23:00.001-07:002019-01-10T21:23:54.972-07:00Triassic Park is Temporarily Closed: What Happens at Petrified Forest During a Government Shutdown [Disclaimer: I am a furloughed Federal employee and this is a personal blog. It is not my intent to take a political side or to make a a political statement here. I am simply explaining what a shutdown is for those who might not understand and its effects on a specific park and program].<br /><br />On December 22, 2018 funding appropriations for the U.S. National Park Service ended. What does this mean? It means that Congress and the President have not allocated funding to allow the Service to pay its bills and keep functioning. There is a little known law on the books called The Antideficiency Act passed in 1884 that prevents "the incurring of obligations or the making of expenditures in excess of amounts available in appropriations of funds". In other words, U.S. Government agencies cannot spend more money each year than they are appropriated by Congress.<br /><br />One of the President's and the Congress' main jobs is to develop a budget each year for the functioning of the Federal Government. If they fail to develop, and pass by law, a Federal budget then the Antideficiency Act kicks in after the last day of lawful appropriations expires. This time that occurred at 12:01 EST on December 22, 2018. The Act requires that the Federal Government initiate a shutdown, which includes the furlough of pre-determined "non-essential" staff and the limitation of services.<br /><br />What is meant by 'non-essential" staff? Basically positions and employees that do not have a health-safety, law enforcement, or cybersecurity role. In National Parks a handful of "essential" staff are kept on the guard the park entrances, and keep up some basic maintenance duties such as water and other utility monitoring. Computer and network monitoring is also provided for. Unfortunately scientific work is not considered essential. It's also important to note that although essential staff are required to work, there is no funding so they do not receive pay for their work time during a shutdown.<br /><br />Since 1976 there have been 22 funding lapses and shutdowns, three in 2018 including the present one. The current one is now a day short of being the longest in history, 22 days. This shutdown is also different because unlike other shutdowns the National Parks have been kept 'open'. The closure of parks during the 17 day 2013 shutdown was not well received by the public and was considered a black eye for the Obama Administration. The current administration did not want to face this and ordered the parks to stay open, but with the greatly reduced "essential" staff. This has led to resource damage, overflowing toilets, etc... situations now being remedied by volunteers and other actions being taken.<br /><br />At Petrified Forest National Park in Arizona the park is closed at night and parks with limited hours are allowed to close those areas normally closed for a portion of the day. Because of the vast amounts of petrified wood and how easily it can be removed the main portion of the park is closed to protect these resources. However, as a service to visitors and travelers on Interstate 40 the restaurant and gas station at the north end of the park, run by a permitted concessionaire, remain open.<br /><br />This has caused a lot of confusion with the public because they see on the news where parks are "open", but don't always realize that only limited services can be offered because there are no staff. So visitor centers and bathrooms are closed at most parks and this is generally unexpected. I highly recommend that anyone planning on visiting a National Park in a shutdown time do some research first to see what is available For example at Petrified Forest the visitor centers are not open, but there are bathroom services. There are also some exhibits and some petrified wood outside of the restaurant. The Grand Canyon is open because it is such a large economic draw for the State of Arizona, that the state is providing the funding to keep some of the basic services operating and some of the park open. Again do some research before visiting and don't expect full services.<br /><br />The thing that is most significant to regular readers of this blog is that the paleontology program at the Petrified Forest (and other units) is a non-essential service and is temporarily closed. Thus park scientists are unable to go to work. This means fossils threatened by erosion don't get collected and preserved, collected fossils don't get prepared or curated, and research does not get done. Fortunately wintertime is not a major collecting season for us so the first point is not critical. However, planning for the summer field season is usually done now and cannot happen and we fall behind in recruiting student interns and working with other researchers. Even more important the NPS scientists cannot apply for external funding sources (e.g., NSF), so we rely on internal grant funding. This year grant proposals were due in January 11, but this year none will be submitted by the deadline. What this means for future grant funding is uncertain.<br /><br />Another thing to realize is that a lot of research in National Parks is done by permitted outside institutions and with a shutdown that work cannot be done, permits and fieldwork are cancelled or postponed. This is not only paleontology but also ecology, archaeology, etc... The park maintains several air quality monitoring stations that require weekly upkeep and data collection. Weeks of non-collection cause sizeable gaps in data that can render a whole year of data unusable. Fortunately this year there was no outside paleontology research work scheduled for this time, although in the 2013 shutdown several research groups were affected. Since that time we try to warn groups not to schedule trips that correspond to funding end periods.<br /><br />Again my purpose here is not to pass judgment on political reasons for this or any other shutdown. I know that a lot of paleontology enthusiasts don't necessarily understand how government shutdowns work and what effects they can have on our scientific work. I hope I have sufficiently explained the process. Those of us who have chosen civil service understand that our work can be temporarily disrupted by funding lapses. Regardless when the park reopens we will get back to our duties of caring for the park fossils and researching their significance for the public and the scientific community. I'm confident that our law enforcement who have to work during the shutdown are doing a great job protecting park resources and explaining this situation to any park visitors. They deserve a lot of thanks.<br /><br /><br />Bill Parkerhttp://www.blogger.com/profile/05941940882532354219noreply@blogger.com0tag:blogger.com,1999:blog-5519292617097628087.post-15537734341155651292019-01-02T17:29:00.000-07:002019-01-02T17:32:07.141-07:00Extinction and the Rise of Dinosaurs - What Will the Microvertebrates Tell Us?Brian Switek has a great <a href="https://blogs.scientificamerican.com/laelaps/extinction-and-the-rise-of-the-dinosaurs/">year end article</a> (based mainly on the recent <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/pala.12399">Allen et al., study</a> in Palaeontology) regarding the loss of most pseudosuchian groups in the end-Triassic extinction and discussion on why the dinosaurs were mostly unaffected.<br /><br />According to their findings body size was not a factor; however, there are not too many data regarding Middle Triassic - Early Jurassic microfaunas. My intern, colleague and Virginia Tech grad student <a href="https://www.globalchange.vt.edu/ben-kligman/">Ben Kligman</a> is adding to this information. Ben started a couple of years ago at Petrified Forest National Park looking at a new microsite in the Blue Mesa Member of the park. This unit and roughly the same horizon had been the subject of several previous microvertebrate studies that despite being nearly two decades apart had generated roughly the same results, a lot of teeth and scales that could only be assigned to broad taxonomic levels. Thus, I was not enthusiastic about this at first. However, Ben tackled this new site with gusto and developing a new sampling technique with the help of PEFOs lead preparator and curator Matt Smith, very quickly built a sample of over 100 different morphotypes. Even more important this new technique allowed preservation of relatively complete jaw elements.<br /><br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-Ci-Zbhd0e4E/XC1WSHjdizI/AAAAAAAACXQ/91aIgU41IEwfsE4DqdpGfptFcVlnuTXLACLcBGAs/s1600/palacrodon.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="694" data-original-width="1081" height="205" src="https://1.bp.blogspot.com/-Ci-Zbhd0e4E/XC1WSHjdizI/AAAAAAAACXQ/91aIgU41IEwfsE4DqdpGfptFcVlnuTXLACLcBGAs/s320/palacrodon.png" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><i>Palacrodon browni</i> from the Chinle Formation of Arizona. <br />From Kligman et al 2018. Acta Palaeotologica Polonica 63(1).</td></tr></tbody></table><br /><br />Ben already has several publications about new these finds (<a href="https://onlinelibrary.wiley.com/doi/full/10.1111/pala.12399">Kligman et al., 2017</a>; <a href="https://www.app.pan.pl/article/item/app004262017.html">Kligman et al., 2018</a>) and several more in the works. Furthermore, this research won the Student Poster Prize at the 2018 Society of Vertebrate Paleontology meeting. Ben is now sampling a wider stratigraphic range of sites and his work will help us further understand the effects of the end-Triassic extinction.Bill Parkerhttp://www.blogger.com/profile/05941940882532354219noreply@blogger.com0tag:blogger.com,1999:blog-5519292617097628087.post-7474998770077299032019-01-01T15:20:00.000-07:002019-01-01T15:20:14.034-07:00New Blog TemnoTalk: A Blog About All Things TemnospondylIntroducing a new blog by my friend and colleague Bryan Gee from the University of Toronto. Since his first find of half of a metoposaur skull in Petrified Forest National Park quite a few years back now Bryan has been obsessed with the fossil record of temnospondyls, a group with constituents that are not always well studied (e.g., Late Triassic North American metoposaurids).<br /><br />Bryan embarked on a series of discoveries at the Petrified Forest that kindled a badly needed interest in these forms and has resulted in quite a few recent publications (<a href="https://peerj.com/articles/3183/?utm_source=TrendMD&utm_campaign=PeerJ_TrendMD_0&utm_medium=TrendMD">Gee et al., 2017</a>; <a href="https://www.researchgate.net/profile/William_Parker12/publication/319377000_A_juvenile_Koskinonodon_perfectus_Temnospondyli_Metoposauridae_from_the_Upper_Triassic_of_Arizona_and_its_implications_for_the_taxonomy_of_North_American_Metoposaurids/links/5b76661692851ca65064f137/A-juvenile-Koskinonodon-perfectus-Temnospondyli-Metoposauridae-from-the-Upper-Triassic-of-Arizona-and-its-implications-for-the-taxonomy-of-North-American-Metoposaurids.pdf">Gee and Parker, 2017</a>; <a href="https://www.tandfonline.com/doi/abs/10.1080/08912963.2018.1480616">Gee and Parker, 2018</a>) and an upcoming paper reexamining the anatomy and taxonomy of the metoposaurid <i>Anaschisma</i>. Bryan is one of the most prolific writers I have ever seen and has published a number of papers now as a graduate student (see his Google Scholar page <a href="https://scholar.google.com/citations?user=WFMkQWoAAAAJ&hl=en">here</a>). I look forward to his blogging and I've added the link to the Chinleana blogroll.Bill Parkerhttp://www.blogger.com/profile/05941940882532354219noreply@blogger.com0tag:blogger.com,1999:blog-5519292617097628087.post-18244315974853250222018-12-24T13:30:00.002-07:002018-12-24T13:30:52.754-07:00New Osteological and Phylogenetic Review of the Triassic Loricatan Prestosuchus chiniquensis from Brazil<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;"><b>Roberto-Da-Silva, L., Müller , R. T., Gallo de França, M. A., Cabreira, S. F., and Dias-Da-Silva, S. 2018. </b><b>An impressive skeleton of the giant top predator <i>Prestosuchus chiniquensis</i> (Pseudosuchia: Loricata) from the Triassic of Southern Brazil, with phylogenetic remarks. Historical Biology <a href="https://www.tandfonline.com/doi/full/10.1080/08912963.2018.1559841">(Early Online).</a></b></div><span style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: x-small;"><b><br /></b></span><b>Abstract - </b>In the present contribution, we aim to present the osteology of ‘ULBRA-PVT-281’, which comprises the best-preserved skeleton of <i>Prestosuchus chiniquensis</i> ever found. ULBRA-PVT-281 combines the morphology of two classic specimens referred to <i>P. chiniquensis</i>, UFRGS-PV-0156-T and UFRGSPV- 0152-T, reunited in a single operational taxonomic unit (OTU) in previous phylogenetic studies. Therefore, the new specimen reinforces the combination of both specimens. We performed a phylogenetic analysis, combining the information of these three specimens plus braincase data from a fourth specimen, UFRGS-PV-0629-T, into a new <i>P. chiniquensis</i> terminal taxon. Moreover, our analysis also included some new taxa potentially related to <i>P. chiniquensis</i>. As a result, we found a topology slightly distinct from previous studies, where <i>Ticinosuchus ferox </i>is the basalmost member of Loricata, which also includes the new combined <i>P. chiniquensis</i>. Our results place <i>P. chiniquensis,</i> <i>Luperosuchus fractus</i>, and <i>Saurosuchus galilei</i> distributed in a pectinate paraphyletic pattern towards Crocodylomorpha. On the other hand, a constrained analysis forcing the monophyly of these taxa demands just a single extra step. Therefore, both scenarios are plausible and agree with the placement of <i>P. chiniquensis</i> within Loricata, whereas <i>T. ferox</i> nests in Loricata only in the unconstrained analysis.Bill Parkerhttp://www.blogger.com/profile/05941940882532354219noreply@blogger.com0tag:blogger.com,1999:blog-5519292617097628087.post-85852920265919969162018-12-23T12:48:00.000-07:002018-12-23T12:48:28.692-07:00Ichnofossil Assemblages and Paleosols of the Upper Triassic Chinle Formation, South-Eastern Utah<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">Adding to our understanding of the understudied Chinle Formation fossils of Utah.</div><div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;"><b><br /></b></div><div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;"><b>Fischer, S. J. and S. T. Hasiotis 2018. Ichnofossil assemblages and palaeosols of the Upper Triassic Chinle Formation, south-eastern Utah (USA): Implications for depositional controls and palaeoclimate. </b></div><div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;"><b>Annales Societatis Geologorum Poloniae 88(2): <a href="http://www.asgp.pl/sites/default/files/volumes/88_2_127_162_Fischer_Hasiotis.pdf">127–162</a>.</b></div><span style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: x-small;"><b><br /></b></span><span style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: x-small;"><b>Abstract -</b> The Upper Triassic Chinle Formation in the Stevens Canyon area in south-eastern Utah represents fluvial, palustrine, and lacustrine strata deposited in a continental back-arc basin on the western edge of Pangea. Previous investigations interpreted a megamonsoonal climate with increasing aridity for the Colorado Plateau towards the end of the Triassic. In this study, we systematically integrate ichnological and pedological features of the Chinle Formation into ichnopedofacies to interpret palaeoenvironmental and palaeoclimatic variations in the north-eastern part of the Chinle Basin. Seventeen ichnofossil morphotypes and six palaeosol orders are combined into twelve ichnopedofacies, whose development was controlled by autocyclic and allocyclic processes and hydrology. Ichnopedofacies are used to estimate palaeoprecipitation in conjunction with appropriate modern analogue latitudinal and geographic settings. In the north-east Chinle Basin, annual precipitation was ~1100–1300 mm in the Petrified Forest Member. Precipitation levels were >1300 mm/yr at the base of the lower Owl Rock Member, decreased to ~700–1100 mm/yr, and then to ~400–700 mm/yr. Two drying upward cycles from ~1100 mm/yr to ~700 mm/yr occurred in the middle and upper part of the Owl Rock Member. In the overlying Church Rock Member, precipitation decreased from ~400 mm/yr at the base of the unit to ~25–325 mm/yr at the end of Chinle Formation deposition. Ichnopedofacies indicate monsoonal conditions persisted until the end of the Triassic with decreasing precipitation that resulted from the northward migration of Pangea. Ichnopedofacies in the northeast Chinle Basin indicate both long-term drying of climate and short-term, wet-dry fluctuations.</span>Bill Parkerhttp://www.blogger.com/profile/05941940882532354219noreply@blogger.com0tag:blogger.com,1999:blog-5519292617097628087.post-26835603069026922852018-12-23T11:16:00.003-07:002018-12-23T11:36:41.474-07:00Expanding the Late Triassic Record of the Dinosaur Precursor Dromomeron romeri: A New Record from the Chinle Formation of Arizona.<div>A new open access paper from my co-worker, friend, and colleague Adam Marsh documenting a new record of the dinosaur precursor <i>Dromomeron romeri</i> from the Chinle Formation Arizona. This further demonstrates the importance of museum collections and apomorphy based identification work to identify stratigraphic, chronologic, and bibliographical extensions, improving our understanding of early dinosaur distributions. </div><b></b><br /><div><b><b><br /></b></b></div><b>Marsh, A. D. 2018. A new record of <i>Dromomeron romeri</i> Irmis et al., 2007 (Lagerpetidae) from the Chinle Formation of Arizona, U.S.A. PaleoBios, 35. Retrieved from <a href="https://escholarship.org/uc/item/8w5755sg">https://escholarship.org/uc/item/8w5755sg</a></b><br /><div><b><br />Abstract -</b> The relatively recent discovery and contextualization of silesaurid and lagerpetid dinosauromorphs has led to a revolution in understanding the early evolutionary history of the dinosaurian lineage. Lagerpetids are known from North America and South America in Middle and Upper Triassic rocks, especially the Chinle Formation of New Mexico and the Dockum Group of Texas. Until now, only a single specimen of <i>Dromomeron gregorii </i>was known from the Upper Triassic Chinle Formation of Arizona. However, a new lagerpetid astragalus specimen (MNA V7237) from the Owl Rock Member of the Chinle Formation found on Ward Terrace in the Navajo Nation of Arizona is referred to<i> Dromomeron romeri</i>. MNA V7237 represents the youngest radioisotopically-dated record of Lagerpetidae, indicating that <i>D. romeri </i>persisted throughout the entire Norian (Otischalkian into the Apachean) in North America.<br /><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://3.bp.blogspot.com/-6VGsChnBWhI/XB_VpymgziI/AAAAAAAACWs/fT3_vQHrRVYQPgnJfsUybrZ4n9pj-M2OwCLcBGAs/s1600/MNA%2BDromomeron%2Bfig%2B2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="470" data-original-width="750" height="400" src="https://3.bp.blogspot.com/-6VGsChnBWhI/XB_VpymgziI/AAAAAAAACWs/fT3_vQHrRVYQPgnJfsUybrZ4n9pj-M2OwCLcBGAs/s640/MNA%2BDromomeron%2Bfig%2B2.jpg" width="640" /></a></div><br /></div>Bill Parkerhttp://www.blogger.com/profile/05941940882532354219noreply@blogger.com0tag:blogger.com,1999:blog-5519292617097628087.post-37943271326817836422018-12-21T00:01:00.002-07:002018-12-21T00:03:05.943-07:00Fuyuanichthys wangi A New Ginklymodian Fish from the Middle Triassic of China<b>Xu, G., Ma, X., and Y. Ren. 2018. <i>Fuyuanichthys wangi gen. et sp. nov.</i> from the Middle Triassic (Ladinian) of China highlights the early diversification of ginglymodian fishes. PeerJ 6:e6054 <a href="https://doi.org/10.7717/peerj.6054">https://doi.org/10.7717/peerj.6054</a></b><br /><div><b><br /></b></div><div><b>Abstract -</b> A series of well-preserved fossil assemblages from the Middle Triassic marine rock succession in Southwest China provide unique evidences for studying the early evolution of holostean fishes, including Halecomorphi (e.g., bownfin) and Ginglymodi (e.g., gars). Ginglymodi have the earliest record in the early Middle Triassic (Anisian, ∼244 Ma) of China, represented by <i>Kyphosichthys</i> and <i>Sangiorgioichthys sui</i> from Yunnan and <i>S. yangjuanensis</i> from Guizhou. Here, we report the discovery of a new ginglymodian, <i>Fuyuanichthys wangi gen. et sp. nov</i>., based on 22 well-preserved specimens from the lower part of the Zhuganpo member of the Falang Formation in eastern Yunnan and western Guizhou, which documents the first discovery of convincing ginglymodians from the late Middle Triassic (Ladinian, ∼240 Ma) Xingyi biota in China. <i>Fuyuanichthys</i> possesses a unique combination of features that easily distinguishes it from other ginglymodians, such as presence of a median gular and short and edentulous maxillae, and absence of a supramaxilla and supraorbitals. As one of the smallest known ginglymodians with a maximum standard length of ∼75 mm, the new finding further supports that the Middle Triassic Ginglymodi have a relatively small range of body sizes compared with the Halecomorphi from the same ecosystems in China. Results of a phylogenetic analysis recover <i>Fuyuanichthys</i> as a sister taxon to <i>Kyphosichthys</i> at the ginglymodian stem, and provide new insights into the early evolution of this clade.</div><div><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://3.bp.blogspot.com/-ZzlRAl_QA2A/XByPqF9OJaI/AAAAAAAACWg/yGmUWuInb6I2GJ0xaBwRutyDzOHshJVbACLcBGAs/s1600/fig-3-2x.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1073" data-original-width="1200" height="357" src="https://3.bp.blogspot.com/-ZzlRAl_QA2A/XByPqF9OJaI/AAAAAAAACWg/yGmUWuInb6I2GJ0xaBwRutyDzOHshJVbACLcBGAs/s400/fig-3-2x.jpg" width="400" /></a></div><div><br /></div><div><br /></div><div><br /></div>Bill Parkerhttp://www.blogger.com/profile/05941940882532354219noreply@blogger.com0tag:blogger.com,1999:blog-5519292617097628087.post-15853071119494961812018-12-20T23:53:00.000-07:002018-12-20T23:56:16.394-07:00New Specimen of Prolacerta broomi from the Early Triassic of Antarctica<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;"><b>Spiekman, S. N. F. 2018. A new specimen of <i>Prolacerta broomi</i> from the lower Fremouw Formation (Early Triassic) of Antarctica, its biogeographical implications and a taxonomic revision. Scientific Reports 8, Article number: 17996. </b><a data-saferedirecturl="https://www.google.com/url?q=https://urldefense.proofpoint.com/v2/url?u%3Dhttps-3A__www.nature.com_articles_s41598-2D018-2D36499-2D6%26d%3DDwMFaQ%26c%3DclK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI%26r%3DRy_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI%26m%3DBBYp30exgT0zi1WBOXFZakSfChg3cNriiDZJLyRRaCo%26s%3DsPsEijM6mRLfNbRJzmbxUi3G7YH8Q1OkjLBuwy5434k%26e%3D&source=gmail&ust=1545460962673000&usg=AFQjCNEriD8jh4-ym21BKegHy2B3ENLYMQ" href="https://urldefense.proofpoint.com/v2/url?u=https-3A__www.nature.com_articles_s41598-2D018-2D36499-2D6&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=BBYp30exgT0zi1WBOXFZakSfChg3cNriiDZJLyRRaCo&s=sPsEijM6mRLfNbRJzmbxUi3G7YH8Q1OkjLBuwy5434k&e=" style="color: #1155cc;" target="_blank">https://www.nature.com/<wbr></wbr>articles/s41598-018-36499-6</a></div><div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;"><br /></div><div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;"><b>Abstract - </b><i>Prolacerta broomi</i> is an Early Triassic archosauromorph of particular importance to the early evolution of archosaurs. It is well known from many specimens from South Africa and a few relatively small specimens from Antarctica. Here, a new articulated specimen from the Fremouw Formation of Antarctica is described in detail. It represents the largest specimen of <i>Prolacerta</i> described to date with a nearly fully articulated and complete postcranium in addition to four skull elements. The study of this specimen and the re-evaluation of other <i>Prolacerta</i> specimens from both Antarctica and South Africa reveal several important new insights into its morphology, most notably regarding the premaxilla, manus, and pelvic girdle. Although well-preserved skull material from Antarctica is still lacking for<i> Prolacerta</i>, a detailed comparison of <i>Prolacerta</i> specimens from Antarctica and South Africa corroborates previous findings that there are no characters clearly distinguishing the specimens from these different regions and therefore the Antarctic material is assigned to<i> Prolacerta broomi</i>. The biogeographical implications of these new findings are discussed. Finally, some osteological characters for <i>Prolacerta</i> are revised and an updated diagnosis and phylogenetic analysis are provided.</div><div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;"><br /></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="https://3.bp.blogspot.com/-9S3o4PgMxu4/XByM3sP_KaI/AAAAAAAACWU/bR_Ic0WcYbUqulqgNHqpwBL_KCMAZcw1gCLcBGAs/s1600/41598_2018_36499_Fig1_HTML.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="533" data-original-width="900" height="377" src="https://3.bp.blogspot.com/-9S3o4PgMxu4/XByM3sP_KaI/AAAAAAAACWU/bR_Ic0WcYbUqulqgNHqpwBL_KCMAZcw1gCLcBGAs/s640/41598_2018_36499_Fig1_HTML.png" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">UWBM 95529 </td></tr></tbody></table><div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;"></div>Bill Parkerhttp://www.blogger.com/profile/05941940882532354219noreply@blogger.com0tag:blogger.com,1999:blog-5519292617097628087.post-7688092361542296092018-12-12T21:04:00.000-07:002018-12-12T21:21:26.892-07:00Further Investigating the Biogeographic Origins of DinosauriaNew paper out in Palaeontology.<br /><br /><b>Marsola, J. C., Ferreira, G. S., Langer, M. C., Button, D. J., and R. J. Butler. 2018. Increases in sampling support the southern Gondwanan hypothesis for the origins of dinosaurs. Palaeontology. Early Online. https://doi.org/10.1111/pala.12411</b><br /><br /><b>Abstract</b> - Dinosaurs were ubiquitous in terrestrial ecosystems through most of the Mesozoic and are still diversely represented in the modern fauna in the form of birds. Recent efforts to better understand the origins of the group have resulted in the discovery of many new species of early dinosaur and their closest relatives (dinosauromorphs). In addition, recent re‐examinations of early dinosaur phylogeny have highlighted uncertainties regarding the interrelationships of the main dinosaur lineages (Sauropodomorpha, Theropoda and Ornithischia), and questioned the traditional hypothesis that the group originated in South Gondwana and gradually dispersed over Pangaea. Here, we use an historical approach to examine the impact of new fossil discoveries and changing phylogenetic hypotheses on biogeographical scenarios for dinosaur origins over 20 years of research time, and analyse the results in the light of different fossil record sampling regimes. Our results consistently optimize South Gondwana as the ancestral area for Dinosauria, as well as for more inclusive clades including Dinosauromorpha, and show that this hypothesis is robust to increased taxonomic and geographic sampling and divergent phylogenetic results. Our results do not find any support for the recently proposed Laurasian origin of dinosaurs and suggest that a southern Gondwanan origin is by far the most plausible given our current knowledge of the diversity of early dinosaurs and non‐dinosaurian dinosauromorphs.<br /><div><br /></div><div>An interesting new study out today that uses phylogeny based biogeographical analyses to test the hypothesis of Baron et al. (2017a,b) that stem-dinosaurs originated in Laurasia. Their results reject that hypothesis in favor of the long standing hypothesis of a Gondwanan origin. I couldn't access the supplemental data in Dryad because the article isn't officially out. I'm not suggesting that the conclusions are wrong, but do have a few questions/comments about the data and how specimen sampling issues from Western North America could affect a rerun of the analysis. </div><div><br /></div><div>1) Some of the separation of taxa into biogeographical bins is confusing. For example most of the Chinle Formation taxa <i>Chindesaurus</i>, <i>Tawa</i>, and <i>Eucoelophysis </i>are shown in green depicting the 'Equatorial Belt' as the ancestral zone, yet taxa from the same formation and localities therein such as <i>Dromomeron gregorii </i>and <i>D. romeri</i> are shown in yellow from the 'Euroamerica' zone. Why are they separated?</div><div><br /></div><div>2) I am not aware of any Rhaetian occurrences of <i>Eucoelophysis baldwini</i>. This taxon occurs in a couple of quarries from around Ghost Ranch, New Mexico and one of them, the Hayden Quarry, is solidly dated in the middle-late Norian at about 212 Ma (Irmis et al., 2011). There is a purported occurrence (Rinehart et al., 2009) of <i>Eucoelophysis</i> from the <i>Coelophysis</i> Quarry at Ghost Ranch that is most likely Rhaetian in age; however, this occurrence is based on the rejected hypothesis that <i>Eucoelophysis</i> remains a neotheropod dinosaur with the holotype representing a highly weathered individual (Rinehart et al., 2009). This referred specimen is simply another specimen of <i>Coelophysis</i>. Thus all presently known occurrences of <i>Eucoelophysis </i>are Norian in age.</div><div><br /></div><div>3) Recent fieldwork in the Chinle Formation, especially at Petrified Forest National Park, has recovered a significant amount of early dinosaur material. This includes the earliest known dated neotheropod specimen and early occurrences of dinosauriforms. This material is presently under study. Combined with already published accounts of silesaurids and coelophysids (e.g., Padian, 1986; Parker et al., 2006), these show a robust record of dinosauromorphs in the early-middle Norian of Arizona. Thus a specimen based study using autapomorphy-based identifications would pull Equatorial Laurasian silesaurids and neotheropods down into the early-middle Norian. Also important is a recently mentioned occurrence of Dromomeron gregorii from the Otischalkian Boren Quarry in the Dockum Group of Texas which is older than any of the Chinle Formation occurrences and pulls these occurrences down even further (Lessner et al., 2018).</div><div><br /></div><div>4) Many of the specimens mentioned above are of interest because they originate from some of the lowest fossil bearing beds in the Chinle Formation, the Blue Mesa Member. To date no diagnostic vertebrate fossils from the Chinle Formation are known from below the middle of the Blue Mesa Member, thus the vertebrate faunas of the lower Chinle (lower Blue Mesa, Mesa Redondo, Shinarump) are unknown. This is significant because these units represent the earliest Norian based on the 'long-Norian' hypothesis (227-208 Ma). Coupled with the Moenkopi/Chinle unconformity much of the well-sampled Triassic of the western U.S. is apparently lacking the Carnian and earliest Norian. This is a bias that should not be ignored. Possible Carnian rocks elsewhere such as the base of the Dockum Group in Texas and units in Wyoming need to be better sampled. </div><div><br /></div><div>It's difficult to say how these details would affect these early dinosaur biogeographical studies, but there are data out there that should be included in future analyses.</div><div><br /></div><div>REFERENCES</div><div><br /></div>Baron, M. G., Norman, D. B. and Barrett, P. M. 2017a. A new hypothesis of dinosaur relationships and early dinosaur evolution. Nature, 543, 501–506.<br /><br />Baron, M. G., Norman, D. B. and Barrett, P. M. 2017b. Baron et al. reply. Nature, 551, E4–E5.<br /><div><br /></div><div>Irmis, R. B., Mundil, R., Martz, J. W., and W. G. Parker. 2011. High resolution U-Pb ages from the Upper Triassic Chinle Formation (New Mexico, U.S.A.) support a diachronous rise of dinosaurs. Earth and Planetary Science Letters 309:258-267.</div><div><br /></div><div>Lessner, E. J., Parker, W. G., Marsh, A. D., Nesbitt, S. J., Irmis, R. B. and B. Mueller. 2018. New insights into Late Triassic dinosauromorph-bearing assemblages from Texas using apomorphy-based identifications. PaleoBios, 35.ucmp_paleobios_39960.</div><div><br /></div><div>Padian, K.. 1986. On the type material of Coelophysis Cope (Saurischia: Theropoda), and a new specimen from the Petrified Forest of Arizona (Late Triassic: Chinle Formation), p. 45-60. In K. Padian (ed.), The beginning of the Age of Dinosaurs: Faunal change across the Triassic-Jurassic boundary. Cambridge University Press, Cambridge.</div><div><br /></div><div>Parker, W. G., Irmis, R. B., and S. J. Nesbitt. 2006. Review of the Late Triassic dinosaur record from Petrified Forest National Park, Arizona. Museum of Northern Arizona Bulletin 62:160-161.</div><div><br /></div><div>Rinehart, L. F., Lucas, S. G., Heckert, A. B., Spielmann, J. A., and M. D. Celeskey. 2009. The paleobiology of <i>Coelophysis bauri</i> (Cope) from the Upper Triassic (Apachean) Whitaker Quarry, New Mexico, with detailed analysis of a single quarry block. New Mexico Museum of Natural History and Science Bulletin 45.</div>Bill Parkerhttp://www.blogger.com/profile/05941940882532354219noreply@blogger.com0tag:blogger.com,1999:blog-5519292617097628087.post-37296126842059706592018-12-10T22:47:00.003-07:002018-12-10T22:47:39.072-07:00New Triassic Vertebrate Papers and the Cold Case of the PhytosaursAfter an almost three year hiatus I am looking to start posting again. Is anyone still out there? Did anyone miss me?<br /><br />Here are a few new Triassic papers officially out today, all open access. A couple were out as early access, but the new phytosaur phylogeny paper is new today in PeerJ. This represents the bulk of the senior authors dissertation, is an exhaustive analysis of the phytosaurs, and a great exercise in database exploration for a group that has been particularly troublesome to deal with taxonomically and phylogenetically.<br /><br />Phytosaurs are an incredible group of archosauriforms, common in Late Triassic rocks. Although problematic they serve as a great group for students to learn basic cranial and skeletal anatomy and we use them for this purpose at the Petrified Forest. Numerous and diverse they go extinct at the end of the Triassic and that is a mystery that colleagues such as Randall Irmis from the University of Utah are trying to solve. This research was featured <a href="https://www.sciencefriday.com/segments/the-cold-case-of-the-triassic-phytosaurs/">last week on Science Friday</a>.<br /><br />Jones, A. S., and R. J. Butler. 2018. A new phylogenetic analysis of Phytosauria (Archosauria: Pseudosuchia) with the application of continuous and geometric morphometric character coding. PeerJ 6:e5901 <a href="https://peerj.com/articles/5901.pdf">DOI 10.7717/peerj.5901</a><br /><br /> Marsola, J. C. A., Bittencourt, J. S., Da Rosa, Á. A. S., Martinelli, A. G., Ribeiro, A. M., Ferigolo, J., and M. C. Langer. 2018. New sauropodomorph and cynodont remains from the Late Triassic <i>Sacisaurus</i> site in southern Brazil and its stratigraphic position in the Norian Caturrita Formation. Acta Palaeontologica Polonica 63 (4): <a href="http://www.app.pan.pl/article/item/app004922018.html">653–669</a>.<div><br /></div><div>Niedźwiedzki, G. and E. Budziszewska-Karwowska. 2018. A new occurrence of the Late Triassic archosaur <i>Smok</i> in southern Poland. Acta Palaeontologica Polonica 68 (4): <a href="http://www.app.pan.pl/article/item/app005052018.html">703–712</a>.</div><div><br /></div><div>De Oliveira, T. M., Oliveira, D., Schultz, C. L., Kerber, L., and F. L. Pinheiro. 2018. Tanystropheid archosauromorphs in the Lower Triassic of Gondwana. Acta Palaeontologica Polonica 63 (4): <a href="http://www.app.pan.pl/article/item/app004892018.html">713–723</a>.<br /><div><br /></div><div><br /></div></div>Bill Parkerhttp://www.blogger.com/profile/05941940882532354219noreply@blogger.com4tag:blogger.com,1999:blog-5519292617097628087.post-4497541633442182202016-01-21T20:42:00.000-07:002016-01-21T20:42:40.755-07:00Aetosaurs: New Phylogenetic Analysis, New Taxon; and New Technique to Analyze Incongruent Character Datasets<div>My <a href="https://peerj.com/articles/1583/">new paper</a> in PeerJ features a new phylogenetic analysis of the Aetosauria (Archosauria: Pseudosuchia). I've added many new characters and feature all known valid aetosaur taxa. In the <a href="https://peerj.com/articles/1583/#supplemental-information">Supplemental Materials</a>, each character is described and figured to clarify them for future use.</div><div><br /></div><div><a href="http://2.bp.blogspot.com/-oWvQLCFjPQo/VqGkP6-7dnI/AAAAAAAAB5k/9PeQey4cNIQ/s1600/Phylo%2Banalysis.jpg" imageanchor="1"><img border="0" height="400" src="http://2.bp.blogspot.com/-oWvQLCFjPQo/VqGkP6-7dnI/AAAAAAAAB5k/9PeQey4cNIQ/s400/Phylo%2Banalysis.jpg" width="352" /></a> </div><div><br /></div><div>This paper also introduces a new aetosaur, <i>Scutarx deltatylus,</i> from the Chinle Formation of Arizona. To date I've collected four partial Scutarx skeletons, the first in 2002, from Petrified Forest National Park. The holotype specimen includes a partial skull, the first good aetosaur skull material collected from Arizona since the 1930s. In previous papers I have assigned all of these specimens to <i>Calyptosuchus</i> (<i>Stagonolepis</i>) <i>wellesi</i>; however, when I undertook a revision of that taxon I noted that my Petrified Forest specimens (all from the Sonsela Member of the Chinle Formation) all possessed raised triangular bosses on the posteromedial corner of the paramdian osteoderms. These are not present in the type specimen from Texas, or from the large amount of material from the Placerias Quarry of Arizona. Interestingly the boss-bearing and non-boss-bearing specimens were separated stratigraphically. Presently the specimens from the Blue Mesa Member of Arizona and the Tecovas Formation of Texas are those that lack the boss (<i>Calyptosuchus wellesi</i>), and those from the Sonsela Member, and middle Cooper Canyon Formation are those that possess the boss (<i>Scutarx deltatylus</i>). The skull and ilium of <i>Scutarx</i> are also autapomorphic as discussed in the paper.</div><div><br /></div><div><a href="http://2.bp.blogspot.com/-KrKu3naCT-U/VqGkUSEVfSI/AAAAAAAAB5w/cisGc9AsmNg/s1600/scutarx.jpg" imageanchor="1"><img border="0" height="400" src="http://2.bp.blogspot.com/-KrKu3naCT-U/VqGkUSEVfSI/AAAAAAAAB5w/cisGc9AsmNg/s400/scutarx.jpg" width="280" /></a></div><div><br /></div><div>Finally I adapted the method to compute Partioned Bremer Support to look at the possibility of character conflict between anatomical partitions in aetosaurs. Essentially does the armor have a different phylogenetic signal than the rest of the skeleton. Bremer Support is used in all phylogenetic analyses to show branch support; however, what is generally not realized is that the individual support values of characters from each anatomical partition combine to total this number. But if these character sets actually support a different tree than the one recovered in the total character analysis, they will reduce the Bremer Support value (negative Bremer Support). Some character sets are ambivalent and actually provide no support to the branches. This analytic tool allows you to look at your tree support node by node and see what character datasets support the topology. This technique has been used since the late 1990s to compare molecular vs. morphological character sets, but this is the first time it has been employed to look at anatomical partitions in a purely morphological study. </div><div><br /></div><div><a href="http://1.bp.blogspot.com/-7fRN3mHhcvQ/VqGkhymSuyI/AAAAAAAAB58/3ZwsE0KpU_Q/s1600/partition.jpg" imageanchor="1"><img border="0" height="400" src="http://1.bp.blogspot.com/-7fRN3mHhcvQ/VqGkhymSuyI/AAAAAAAAB58/3ZwsE0KpU_Q/s400/partition.jpg" width="375" /></a></div><div><br /></div><div>That said, I am a little disappointed with my final discussion section in the paper. While I am excited about the potential for Partitioned Bremer Support, I still am learning all that it demonstrates, thus my discussion is not as strong as I would have liked. I hope that others will find it of interest and utility and that we can see if if it works for other taxonomic groups. </div><b><div><b><br /></b></div><div><b><br /></b></div>Parker, W.G. 2016. Revised phylogenetic analysis of the Aetosauria (Archosauria: Pseudosuchia); assessing the effects of incongruent morphological character sets. PeerJ 4:e1583 <a href="https://doi.org/10.7717/peerj.1583">https://doi.org/10.7717/peerj.1583</a></b><div><b><br /></b></div><b>Abstract- </b>Aetosauria is an early-diverging clade of pseudosuchians (crocodile-line archosaurs) that had a global distribution and high species diversity as a key component of various Late Triassic terrestrial faunas. It is one of only two Late Triassic clades of large herbivorous archosaurs, and thus served a critical ecological role. Nonetheless, aetosaur phylogenetic relationships are still poorly understood, owing to an overreliance on osteoderm characters, which are often poorly constructed and suspected to be highly homoplastic. A new phylogenetic analysis of the Aetosauria, comprising 27 taxa and 83 characters, includes more than 40 new characters that focus on better sampling the cranial and endoskeletal regions, and represents the most comprenhensive phylogeny of the clade to date. Parsimony analysis recovered three most parsimonious trees; the strict consensus of these trees finds an Aetosauria that is divided into two main clades: Desmatosuchia, which includes the Desmatosuchinae and the Stagonolepidinae, and Aetosaurinae, which includes the Typothoracinae. As defined Desmatosuchinae now contains <i>Neoaetosauroides engaeus</i> and several taxa that were previously referred to the genus <i>Stagonolepis</i>, and a new clade, Desmatosuchini, is erected for taxa more closely related to <i>Desmatosuchus</i>. Overall support for some clades is still weak, and Partitioned Bremer Support (PBS) is applied for the first time to a strictly morphological dataset demonstrating that this weak support is in part because of conflict in the phylogenetic signals of cranial versus postcranial characters. PBS helps identify homoplasy among characters from various body regions, presumably the result of convergent evolution within discrete anatomical modules. It is likely that at least some of this character conflict results from different body regions evolving at different rates, which may have been under different selective pressures.Bill Parkerhttp://www.blogger.com/profile/05941940882532354219noreply@blogger.com0tag:blogger.com,1999:blog-5519292617097628087.post-4135558128189304412016-01-12T01:03:00.000-07:002016-01-12T01:03:36.028-07:00Cranial Anatomy of the Aetosaur Paratypothorax andressorum<b>Schoch, R. R., and J. B. Desojo. 2016. Cranial anatomy of the aetosaur <i>Paratypothorax andressorum</i> Long & Ballew, 1985, from the Upper Triassic of Germany and its bearing on aetosaur phylogeny. Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 279(1):73-95. DOI: <a href="http://dx.doi.org/10.1127/njgpa/2016/0542">http://dx.doi.org/10.1127/njgpa/2016/0542</a><br /><a href="http://www.ingentaconnect.com/content/schweiz/njbgeol/2016/00000279/00000001/art00008">http://www.ingentaconnect.com/content/schweiz/njbgeol/2016/00000279/00000001/art00008</a><br /><br /><br />Abstract - </b>The large aetosaur <i>Paratypothorax andressorum</i> has so far been known only by its osteoderms. Here we describe for the first time the skull of a complete, articulated specimen of this taxon that was found in the type horizon at Murrhardt, southwestern Germany. Paratypothorax<br />andressorum has the following cranial autapomorphies: (1) upper jaw margin with deep notch between premaxilla and maxilla, (2) maxilla-lacrimal suture with finger-like projection, (3) upper<br />temporal fenestra triangular, and (4) first paramedian cervical osteoderms narrow and oval, much smaller than second row. Apart from these features, the skull of <i>P. andressorum</i> closely resembles that of the small aetosaur <i>Aetosaurus ferratus</i> known from the same horizons, despite major differences in the morphology of osteoderms. Both taxa share (1) the pointed, beak-shaped premaxilla which expands only gently anterior to the nasal, (2) maxilla and lacrimal excluding jugal<br />from margin of antorbital fenestra, (3) exclusion of squamosal from margin of infratemporal fenestra, and (4) posterior part of jugal not downturned. Phylogenetic analysis reveals poorly resolved relationships within Aetosauria, but exclusion of a problematic taxon <i>Coahomasuchus</i> results in a much better resolution, with <i>Paratypothorax</i> to nest with <i>Rioarribasuchus</i>, <i>Tecovasuchus</i>, <i>Typothorax</i>, and <i>Redondasuchus</i> within a monophyletic Typothoracinae. Interestingly, <i>Aetosaurus</i> and <i>Stenomyti</i> form successive sister taxa of this clade rather than fall within an aetosaurine grade of basal aetosaurs, as suggested by previous authors. The resemblance of <i>Paratypothorax </i>and <i>Aetosaurus</i> in many cranial features, their close relationship as suggested by the present analysis, and the immature state of all available <i>Aetosaurus </i>specimens suggest two new alternative hypotheses: (1) <i>Aetosaurus</i> is the juvenile of a close relative of <i>Paratypothorax</i> or (2) it is itself the juvenile of <i>Paratypothorax</i>.Bill Parkerhttp://www.blogger.com/profile/05941940882532354219noreply@blogger.com0tag:blogger.com,1999:blog-5519292617097628087.post-62260948880848913252016-01-12T00:56:00.001-07:002016-01-12T00:56:49.540-07:00Archosauromorph from the Middle Permian of South America<b>Martinelli, A. G., Francischini, H., Dentzien-Dias, P. C., Soares, M. B., and C. L. Schultz. 2016.<br />The oldest archosauromorph from South America: postcranial remains from the Guadalupian (mid-Permian) Rio do Rasto Formation (Paraná Basin), southern Brazil. Historical Biology.<br />DOI:10.1080/08912963.2015.1125897<br /><a href="http://www.tandfonline.com/doi/full/10.1080/08912963.2015.1125897">http://www.tandfonline.com/doi/full/10.1080/08912963.2015.1125897</a><br /><br /><br />Abstract -</b> In this contribution, we report a distal portion of a left humerus that likely belongs to an indeterminate basal archosauromorph from the Guadalupian (mid-Permian) Rio do Rastro Formation (Paraná Basin) of southern Brazil. A precise taxonomy of the fragmented and isolated humerus UFRGS-PV-0546-P is not warranted at generic nor familiar level but, likely, this specimen belongs to an Archosauromorpha due to the lack of both the entepicondylar and the ectepicondylar foramina. The narrow distal end of the humerus, the rounded radial and ulnar condyles, and the moderately developed supinator process with a shallow ectepicondylar groove (not notched) are features reminiscent of tanystropheids rather than that of other archosauromorphs. This material likely represents the first and oldest Permian archosauromorph from South America and indicates the presence of this lineage before the P/T boundary.Bill Parkerhttp://www.blogger.com/profile/05941940882532354219noreply@blogger.com0tag:blogger.com,1999:blog-5519292617097628087.post-86354253853853208742016-01-12T00:53:00.001-07:002016-01-12T00:53:29.578-07:00The Early Evolution of Rhynchosaurs Congratulations to Max Langer for being honored with his own rhynchosaur genus.<br /><br /><b>Ezcurra, M. D., Montefeltro, F., and R. J. Butler. 2016. The Early Evolution of Rhynchosaurs. Frontiers in Ecology and Evolution 3:142. DOI: 10.3389/fevo.2015.00142. <a href="http://journal.frontiersin.org/article/10.3389/fevo.2015.00142/full">http://journal.frontiersin.org/article/10.3389/fevo.2015.00142/full</a><br /><br />Abstract - </b>The rhynchosaurian archosauromorphs are an important and diverse group of fossil tetrapods that first appeared during the Early Triassic and probably became extinct during the early Late Triassic (early Norian). Here, the early evolution of rhynchosaurs during the Early and early Middle Triassic (Induan-Anisian: 252.2-242 Mya) is reviewed based on new anatomical observations and their implications for the taxonomy, phylogenetic relationships and macroevolutionary history of the group. A quantitative phylogenetic analysis recovered a paraphyletic genus <i>Rhynchosaurus</i>, with “<i>Rhynchosaurus</i>” <i>brodiei</i> more closely related to hyperodapedontines than to <i>Rhynchosaurus</i> <i>articeps</i>. Therefore, a new genus is erected, resulting in the new combination <i>Langeronyx brodiei</i>. A body size analysis found two independent increases in size in the evolutionary history of rhynchosaurs, one among stenaulorhynchines and the other in the hyperodapedontine lineage. Maximum likelihood fitting of phenotypic evolution models to body size data found ambiguous results, with body size evolution potentially interpreted as fitting either a non-directional Brownian motion model or a stasis model. A Dispersal-Extinction Cladogenesis analysis reconstructed the areas that are now South Africa and Europe as the ancestral areas of Rhynchosauria and Rhynchosauridae, respectively. The reconstruction of dispersal events between geographic areas that are broadly separated paleolatitudinally implies that barriers to the dispersal of rhynchosaurs from either side of the paleo-Equator during the Middle Triassic were either absent or permeable.Bill Parkerhttp://www.blogger.com/profile/05941940882532354219noreply@blogger.com1tag:blogger.com,1999:blog-5519292617097628087.post-45386794275380050912016-01-12T00:47:00.000-07:002016-01-12T01:08:44.461-07:00Archosauriform Remains from Late Triassic of San Luis Province, Argentina<b>Gianechini, F. A., Codorniú, L., Arcucci, A. B., Elías, G. C., and D. Rivarola. 2015. Archosauriform remains from the Late Triassic of San Luis province, Argentina, Quebrada del Barro Formation, Marayes–El Carrizal Basin. Journal of South American Earth Sciences. DOI:10.1016/j.jsames.2015.12.012<br /><a href="http://www.sciencedirect.com/science/article/pii/S0895981115301073">http://www.sciencedirect.com/science/article/pii/S0895981115301073</a><br /><br /><br />Abstract-</b> Here we present archosauriform remains from ‘Abra de los Colorados’, a fossiliferous locality at Sierra de Guayaguas, NW San Luis Province. Two fossiliferous levels were identified in outcrops of the Quebrada del Barro Formation (Norian), which represent the southernmost outcrops of the Marayes–El Carrizal Basin. These levels are composed by massive muddy lithofacies, interpreted as floodplain deposits. The specimens consist of one incomplete maxilla (MIC-V718), one caudal vertebra (MIC-V719), one metatarsal (MIC-V720) and one indeterminate appendicular bone (MIC-V721). The materials can be assigned to Archosauriformes but the fragmentary nature and lack of unambiguous synapomorphies preclude a more precise taxomic assignment. The maxilla is remarkably large and robust and represents the posterior process. It preserved one partially erupted tooth with ziphodont morphology. This bone shows some anatomical traits and size match with ‘rauisuchians’ and theropods. MIC-V719 corresponds to a proximal caudal vertebra. It has a high centrum, a ventral longitudinal furrow, expanded articular processes for the chevrons, a posteriorly displaced diapophysis located below the level of the prezygapophyses, and short prezygapophyses. This vertebra would be from an indeterminate archosauriform. MIC-V720 presents a cylindrical diaphysis, with a well-developed distal trochlea, which present resemblances with metatarsals of theropods, pseudosuchians, and silesaurids, although the size matches better with theropods. MIC-V721 has a slender diaphysis and a convex triangular articular surface, and corresponds to an indeterminate archosauriform. Despite being fragmentary, these materials indicate the presence of a diverse archosauriforms association from Late Triassic beds of San Luis. Thus, they add to the faunal assemblage recently reported from this basin at San Juan Province, which is much rich and diverse than the coeval paleofauna well known from Los Colorados Formation in the Ischigualasto–Villa Union Basin.Bill Parkerhttp://www.blogger.com/profile/05941940882532354219noreply@blogger.com0tag:blogger.com,1999:blog-5519292617097628087.post-53066451105566749642015-09-09T21:49:00.000-07:002015-09-09T21:49:04.889-07:00Reanalysis of the Diapsid Reptile Elachistosuchus huenei from the Late Triassic of Germany<b>Sobral, G., Sues, H.-D., and J. Müller. 2015. Anatomy of the enigmatic reptile <i>Elachistosuchus huenei</i> Janensch, 1949 (Reptilia: Diapsida) from the Upper Triassic of Germany and its relevance for the origin of Sauria. PLoS ONE 10(9): e0135114. <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0135114">doi:10.1371/journal.pone.0135114</a></b><br /><b><br /></b><b>Abstract</b> - The holotype and only known specimen of the enigmatic small reptile <i>Elachistosuchus huenei</i>Janensch, 1949 from the Upper Triassic (Norian) Arnstadt Formation of Saxony-Anhalt (Germany) is redescribed using μCT scans of the material. This re-examination revealed new information on the morphology of this taxon, including previously unknown parts of the skeleton such as the palate, braincase, and shoulder girdle. <i>Elachistosuchus</i> is diagnosed especially by the presence of the posterolateral process of the frontal, the extension of the maxillary tooth row to the posterior margin of the orbit, the free posterior process of the jugal, and the notched anterior margin of the interclavicle. Phylogenetic analyses using two recently published character-taxon matrices recovered conflicting results for the phylogenetic position of <i>Elachistosuchus</i>–either as an archosauromorph, as a lepidosauromorph or as a more basal, non-saurian diapsid. These different placements highlight the need of a thorough revision of critical taxa and new character sets used for inferring neodiapsid relationships.Bill Parkerhttp://www.blogger.com/profile/05941940882532354219noreply@blogger.com0tag:blogger.com,1999:blog-5519292617097628087.post-75807283801182601862015-08-29T17:41:00.001-07:002015-08-29T17:41:05.347-07:00The Dicynodon-Lystrosaurus Assemblage Zone Boundary May Not Approximate the Marine-Defined Permo-Triassic Extinction Event<div>Wow, well this should definitely generate some discussion and a bit of research.... </div><b><div><b><br /></b></div>Gastaldo, R. A., Kamo, S. L., Neveling, J., Geissman, J. W., Bamford, M., and C. V. Looy. 2015 Is the vertebrate-defined Permian-Triassic boundary in the Karoo Basin, South Africa, the terrestrial expression of the end-Permian marine event? Geology (Advanced Online). doi: 10.1130/G37040.1</b><b><br /></b><b>Abstract: </b>The end-Permian extinction records the greatest ecological catastrophe in Earth history. The vertebrate fossil record in the Karoo Basin, South Africa, has been used for more than a century as the standard for understanding turnover in terrestrial ecosystems, recently claimed to be in synchrony with the marine crisis. Workers assumed that systematic turnover at the <i>Dicynodon</i> assemblage zone boundary, followed by the appearance of new taxa directly above the base of the <i>Lystrosaurus</i>assemblage zone, is the continental expression of the end-Permian event and recovery. To test this hypothesis, we present the first highprecision age on strata close to the inferred Permian-Triassic boundary. A U-Pb isotope dilution–thermal ionization mass spectrometry zircon age of 253.48 ± 0.15 Ma (early Changhsingian) is from a silicified ash layer ~60 m below the current vertebrate-defined boundary at Old Lootsberg Pass (southern South Africa). This section yields newly discovered plants and vertebrates, and is dominated by a normal polarity signature. Our collective data suggest that the <i>Dicynodon-Lystrosaurus</i>assemblage zone boundary is stratigraphically higher than currently reported, and older than the marine extinction event. Therefore, the turnover in vertebrate taxa at this biozone boundary probably does not represent the biological expression of the terrestrial end-Permian mass extinction. The actual Permian-Triassic boundary in the Karoo Basin is either higher in the Katberg Formation or is not preserved. The currently accepted model of the terrestrial ecosystem response to the crisis, both in this basin and its extension globally, requires reevaluation.Bill Parkerhttp://www.blogger.com/profile/05941940882532354219noreply@blogger.com0tag:blogger.com,1999:blog-5519292617097628087.post-72450246452934724342015-08-11T23:34:00.000-07:002015-08-11T23:34:23.679-07:00So Long Paleorhinus and Pseudopalatinae<div>Long needed redescription of the type material of the phytosaur <i>Parasuchus hislopi </i>from India and a revision of the non-mystriosuchin parasuchid phytosaurs. It will take me awhile to abandon the name Pseudopalatinae. </div><div><b><br /></b></div><div><b>Kammerer, C. F., Butler, R. J., Bandyopadhyay, S., and M. R. Stocker. 2015. Relationships of the Indian phytosaur <i>Parasuchus hislopi </i>Lydekker, 1885. Papers in Paleontology (<a href="http://onlinelibrary.wiley.com/doi/10.1002/spp2.1022/abstract">early online</a>). </b></div><b><div><b><br /></b></div>Abstract:</b> The neotype skull of the Indian phytosaur <i>Parasuchus hislopi</i> Lydekker, 1885 (ISI R42) is re-evaluated and compared with the type material of other basal phytosaurs. <i>Parasuchus hislopi</i> is extremely similar to species previously placed in <i>Paleorhinus</i> (<i>P. bransoni</i> and <i>P. angustifrons</i>), sharing with them such characters as a series of nodes on the lateral surface of the jugal, paired ridges on the squamosal and a frontal depression. <i>Parasuchus hislopi</i> represents a valid species: it can be distinguished from <i>P. bransoni</i> by a relatively low narial eminence and <i>P. angustifrons</i> by the absence of paired nasal depressions. Inclusion of <i>Parasuchus hislopi</i> in a phylogenetic analysis of phytosaurs recovers it in a well-supported clade with <i>P. bransoni</i> and <i>P. angustifrons</i>. <i>Parasuchus</i> is considered the senior synonym of <i>Paleorhinus</i> and <i>Arganarhinus</i>. <i>Parasuchus</i> (here considered to include <i>P. hislopi</i>, <i>P. angustifrons</i>, <i>P. bransoni</i> and <i>P. magnoculus</i>) has a broad circum-Pangaean distribution, with species occurring in the south-western United States, Morocco, central Europe and India. Phytosaur higher-level taxonomy is also revised: Parasuchidae is redefined to include ‘<i>Paleorhinus</i>-grade’ phytosaurs and the later-diverging Mystriosuchinae (the group formerly known as Phytosauridae), and Pseudopalatinae is renamed Mystriosuchini for reason of priority.Bill Parkerhttp://www.blogger.com/profile/05941940882532354219noreply@blogger.com12tag:blogger.com,1999:blog-5519292617097628087.post-69317995754861164632015-08-09T23:31:00.000-07:002015-08-10T22:56:27.620-07:00A New Lagerpetid Dinosauromorph from the Late Triassic of Argentina<b>Martínez, R. N., Apaldetti, C., Correa, G. A., and D. Abelín. 2015. A Norian lagerpetid dinosauromorph from the Quebrada del Barro Formation, northwestern Argentina. Ameghiniana (future issue) <a href="http://www.ameghiniana.org.ar/index.php/ameghiniana/article/view/1036">doi:10.5710/AMGH.21.06.2015.2894</a><br /><br />Abstract:</b> The early evolution of Ornithodira, the clade that includes pterosaurs and dinosaurs, is poorly known. Until a decade ago, the basal radiation of Dinosauromorpha, the clade including dinosaurs and birds, was poorly understood because of a scarce of fossil record, which was restricted to specimens known of the Ladinian Chañares Formation from Argentina. In the last years the discovery of several non-dinosaurian dinosauromorphs dramatically expanded this record and also demonstrated that this group—previously restricted to the Middle Triassic—persisted at least well into the Norian. Although Norian non-dinosaurian dinosauromorphs have been reported from several places around the world, the only known Norian non-dinosauriform dinosauromorphs—<i>Dromomeron romeri</i> and <i>Dromomeron gregorii</i>—come from North America. We report here the first record from the Southern Hemisphere of a non-dinosauriform dinosauromorph, <i>Dromomeron gigas sp. nov.</i>, from the Norian Quebrada del Barro Formation, northwestern Argentina. A phylogenetic analysis recovers <i>Dromomeron gigas</i> nested into the monophyletic group Lagerpetidae, and as the sister taxon to <i>Dromomeron romeri</i>. The inclusion of <i>D. gigas</i> within Lagerpetidae suggests that body size increased in this lineage over time, as was previously demonstrated for Dinosauriformes as a whole, and that lagerpetids reached a larger size than previously thought. Finally, the new finding provides novel information on the basal radiation of Dinosauromorpha constituting the first record of a Norian association of dinosaurs with non-dinosauriform dinosauromorphs outside North America.Bill Parkerhttp://www.blogger.com/profile/05941940882532354219noreply@blogger.com0tag:blogger.com,1999:blog-5519292617097628087.post-48300770312443314682015-03-29T21:57:00.003-07:002015-03-29T21:57:54.510-07:00Evidence of Interaction between Two Late Triassic Apex Predators<span style="background-color: white; color: #444444; font-family: 'Open Sans', Helvetica, Arial, sans-serif; font-size: 14px; line-height: 24px;">I've been away for a bit, but am interested in trying to get back into the swing of things here so please bear with me. This is a paper from late last year that I haven't mentioned before.</span><br /><span style="background-color: white; color: #444444; font-family: 'Open Sans', Helvetica, Arial, sans-serif; font-size: 14px; line-height: 24px;"><br /></span><span style="background-color: white; color: #444444; font-family: 'Open Sans', Helvetica, Arial, sans-serif; font-size: 14px; line-height: 24px;">Drumheller, S. K., M. R. Stocker, and S. J. Nesbitt. 2014. Direct evidence of trophic interactions among apex predators in the Late Triassic of western North America. Naturwissenschaften 101:975-987. DOI 10.1007/s00114-014-1238-3</span><br /><span style="background-color: white; color: #444444; font-family: 'Open Sans', Helvetica, Arial, sans-serif; font-size: 14px; line-height: 24px;"><br /></span><span style="background-color: white; color: #444444; font-family: 'Open Sans', Helvetica, Arial, sans-serif; font-size: 14px; line-height: 24px;">Rather than get into the details here I'll send you to <a href="http://www.pasttime.org/podcast/quick-bite-clash-of-the-triassic-titans/">this podcast </a>which does a great job featuring the significance of this study.</span>Bill Parkerhttp://www.blogger.com/profile/05941940882532354219noreply@blogger.com0