88 research outputs found

    New specimen and redescription of Anisodontosaurus greeri (Moenkopi Formation: Middle Triassic) and the spatiotemporal origins of Trilophosauridae

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    Anisodontosaurus greeri is an enigmatic small-bodied tetrapod with a heterodont dentition from the Holbrook Member of the Moenkopi Formation (Middle Triassic) of Arizona (U.S.A.). The evolutionary relationships of this taxon have long been debated and remain uncertain. Using micro-computed tomography (µCT) scans we redescribe the holotype of Anisodontosaurus greeri (UCMP 37804), as well as an additional specimen (MNA.V.1478) that had been informally referred to this taxon. Our new data reveal hidden details of the dentition (i.e., ankylothecodonty and absence of replacement teeth) that, in combination with the tricuspid and mediolaterally expanded crowns, support a referral of both specimens to the archosauromorph clade Trilophosauridae. The referral of MNA.V.1478 to Anisodontosaurus greeri is supported by the unique anatomy of the highly differentiated dentition (i.e., ‘figure of 8’-shaped premolariforms in occlusal views; mesiodistally short tooth row; presence of a distal ‘molariform’ crown). Comparison of Anisodontosaurus greeri with other trilophosaurids highlights marked similarities with Variodens inopinatus from the Upper Triassic deposits of the U.K. Our cladistic analyses confirm these observations, and recover, for the first time, two distinct lineages within Trilophosauridae: one geologically long-lived and comprising Anisodontosaurus and Variodens; and one comprising Tricuspisaurus, Trilophosaurus spp., and Spinosuchus. These results imply that: (i) Anisodontosaurus is one of the oldest known trilophosaurids worldwide and the oldest in North America; (ii) trilophosaurids achieved a broad distribution at low latitudes within western Pangea by the Middle Triassic; (iii) small body sizes were more common than previously thought among trilophosaurids

    A new short-faced archosauriform from the Upper Triassic Placerias/Downs’ quarry complex, Arizona, USA, expands the morphological diversity of the Triassic archosauriform radiation

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    The Placerias/Downs’ Quarry complex in eastern Arizona, USA, is the most diverse Upper Triassic vertebrate locality known. We report a new short-faced archosauriform, Syntomiprosopus sucherorum gen. et sp. nov., represented by four incomplete mandibles, that expands that diversity with a morphology unique among Late Triassic archosauriforms. The most distinctive feature of Syntomiprosopus gen. nov. is its anteroposteriorly short, robust mandible with 3–4 anterior, a larger caniniform, and 1–3 “postcanine” alveoli. The size and shape of the alveoli and the preserved tips of replacement teeth preclude assignment to any taxon known only from teeth. Additional autapomorphies of S. sucherorum gen. et sp. nov. include a large fossa associated with the mandibular fenestra, an interdigitating suture of the surangular with the dentary, fine texture ornamenting the medial surface of the splenial, and a surangular ridge that completes a 90° arc. The external surfaces of the mandibles bear shallow, densely packed, irregular, fine pits and narrow, arcuate grooves. This combination of character states allows an archosauriform assignment; however, an associated and similarly sized braincase indicates that Syntomiprosopus n. gen. may represent previously unsampled disparity in early-diverging crocodylomorphs. The Placerias Quarry is Adamanian (Norian, maximum depositional age ~219 Ma), and this specimen appears to be an early example of shortening of the skull, which occurs later in diverse archosaur lineages, including the Late Cretaceous crocodyliform Simosuchus. This is another case where Triassic archosauriforms occupied morphospace converged upon by other archosaurs later in the Mesozoic and further demonstrates that even well-sampled localities can yield new taxa

    Ecomorphometric Analysis of Diversity in Cranial Shape of Pygopodid Geckos

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    Pygopodids are elongate, functionally limbless geckos found throughout Australia. The clade presents low taxonomic diversity (∼45 spp.), but a variety of cranial morphologies, habitat use, and locomotor abilities that vary between and within genera. In order to assess potential relationships between cranial morphology and ecology, computed tomography scans of 29 species were used for 3D geometric morphometric analysis. A combination of 24 static landmarks and 20 sliding semi-landmarks were subjected to Generalized Procrustes Alignment. Disparity in cranial shape was visualized through Principal Component Analysis, and a multivariate analysis of variance (MANOVA) was used to test for an association between shape, habitat, and diet. A subset of 27 species with well-resolved phylogenetic relationships was used to generate a phylomorphospace and conduct phylogeny-corrected MANOVA. Similar analyses were done solely on Aprasia taxa to explore species-level variation. Most of the variation across pygopodids was described by principal component (PC) 1(54%: Cranial roof width, parabasisphenoid, and occipital length), PC2 (12%: Snout elongation and braincase width), and PC3 (6%: Elongation and shape of the palate and rostrum). Without phylogenetic correction, both habitat and diet were significant influencers of variation in cranial morphology. However, in the phylogeny-corrected MANOVA, habitat remained weakly significant, but not diet, which can be explained by genericlevel differences in ecology rather than among species. Our results demonstrate that at higher levels, phylogeny has a strong effect on morphology, but that influence may be due to small sample size when comparing genera. However, because some closely related taxa occupy distant regions of morphospace, diverging diets, and use of fossorial habitats may contribute to variation seen in these geckos.This work was supported by SUNY Oswego RISE (to G.G.) and the U.S. National Science Foundation (grant number DEB 1655610 to J.C.O and M.R.S.)

    Genetic loci and prioritization of genes for kidney function decline derived from a meta-analysis of 62 longitudinal genome-wide association studies

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    Estimated glomerular filtration rate (eGFR) reflects kidney function. Progressive eGFR-decline can lead to kidney failure, necessitating dialysis or transplantation. Hundreds of loci from genome-wide association studies (GWAS) for eGFR help explain population cross section variability. Since the contribution of these or other loci to eGFR-decline remains largely unknown, we derived GWAS for annual eGFR-decline and meta-analyzed 62 longitudinal studies with eGFR assessed twice over time in all 343,339 individuals and in high-risk groups. We also explored different covariate adjustment. Twelve genome-wide significant independent variants for eGFR-decline unadjusted or adjusted for eGFR-baseline (11 novel, one known for this phenotype), including nine variants robustly associated across models were identified. All loci for eGFR-decline were known for cross-sectional eGFR and thus distinguished a subgroup of eGFR loci. Seven of the nine variants showed variant-by-age interaction on eGFR cross section (further about 350,000 individuals), which linked genetic associations for eGFR-decline with age-dependency of genetic cross-section associations. Clinically important were two to four-fold greater genetic effects on eGFR-decline in high-risk subgroups. Five variants associated also with chronic kidney disease progression mapped to genes with functional in-silico evidence (UMOD, SPATA7, GALNTL5, TPPP). An unfavorable versus favorable nine-variant genetic profile showed increased risk odds ratios of 1.35 for kidney failure (95% confidence intervals 1.03-1.77) and 1.27 for acute kidney injury (95% confidence intervals 1.08-1.50) in over 2000 cases each, with matched controls). Thus, we provide a large data resource, genetic loci, and prioritized genes for kidney function decline, which help inform drug development pipelines revealing important insights into the age-dependency of kidney function genetics

    Genomic investigations of unexplained acute hepatitis in children

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    Since its first identification in Scotland, over 1,000 cases of unexplained paediatric hepatitis in children have been reported worldwide, including 278 cases in the UK1. Here we report an investigation of 38 cases, 66 age-matched immunocompetent controls and 21 immunocompromised comparator participants, using a combination of genomic, transcriptomic, proteomic and immunohistochemical methods. We detected high levels of adeno-associated virus 2 (AAV2) DNA in the liver, blood, plasma or stool from 27 of 28 cases. We found low levels of adenovirus (HAdV) and human herpesvirus 6B (HHV-6B) in 23 of 31 and 16 of 23, respectively, of the cases tested. By contrast, AAV2 was infrequently detected and at low titre in the blood or the liver from control children with HAdV, even when profoundly immunosuppressed. AAV2, HAdV and HHV-6 phylogeny excluded the emergence of novel strains in cases. Histological analyses of explanted livers showed enrichment for T cells and B lineage cells. Proteomic comparison of liver tissue from cases and healthy controls identified increased expression of HLA class 2, immunoglobulin variable regions and complement proteins. HAdV and AAV2 proteins were not detected in the livers. Instead, we identified AAV2 DNA complexes reflecting both HAdV-mediated and HHV-6B-mediated replication. We hypothesize that high levels of abnormal AAV2 replication products aided by HAdV and, in severe cases, HHV-6B may have triggered immune-mediated hepatic disease in genetically and immunologically predisposed children

    The first amphisbaenians from Texas, with notes on other squamates from the middle Eocene Purple Bench locality

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    <p>The shift to a cooler and drier climate through the Paleogene has been interpreted as the driver for changes in diversity and biogeographic distributions among mammalian taxa during the Eocene, leading to hypotheses of continued tropical climatic refugia in West Texas through the middle and late Eocene. However, the presence of ectothermic reptiles during that time has not been documented in detail and would potentially provide additional climatic indicators. We provide the first description of the herpetofauna from the Devil's Graveyard Formation (DGF), West Texas, the southernmost, well-sampled middle Eocene basin in North America. Specimens are derived from beds correlated with the Ui3 biochron of the late Uintan North American Land Mammal ‘Age’ (∼45–40 Ma). We report the first amphisbaenians known from Texas, expanding our spatial and climatic understanding of rhineurid distribution, as well as the first glyptosaurine anguimorphs and alethinophidian snakes from the Purple Bench assemblage. These new amphisbaenians preserve a jugal posteriorly enclosing the orbit and an extremely short retroarticular process and are recovered in a clade comprising †<i>Spathorhynchus</i>, †<i>Dyticonastis</i>, †<i>Ototriton</i>, and †<i>Hyporhina</i>. The documentation of the amphisbaenians and other squamates provides biogeographic range extensions of these taxa to West Texas. Despite suggestions that West Texas was a middle and late Eocene climatic refugium for mammals adapted to subtropical forested environments, rhineurid amphisbaenians show a wide range of temperature tolerances up to the beginning of the Neogene.</p> <p>http://zoobank.org/urn:lsid:zoobank.org:pub:3E55D6BF-0691-4220-9212-0407F454BE53</p> <p>SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at <a href="http://www.tandfonline.com/UJVP" target="_blank">www.tandfonline.com/UJVP</a></p> <p>Citation for this article: Stocker, M. R., and E. C. Kirk. 2016. The first amphisbaenians from Texas, with notes on other squamates from the middle Eocene Purple Bench locality. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2016.1094081.</p

    Preface: Festschrift for Wann Langston, Jr.

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    Redescription of the phytosaurs Paleorhinus ('Francosuchus') angustifrons and Ebrachosuchus neukami from Germany, with implications for Late Triassic biochronology

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    Figure 3. Paleorhinus angustifrons (Kuhn, 1936), BSPG 1931 X 502. Photographs of holotype skull in dorsal (A), ventral (B), posterior (C), and left lateral (D) views. Asterisks show positions of transverse sections shown in Figure 8.Published as part of Butler, Richard J., Rauhut, Oliver W. M., Stocker, Michelle R. & Bronowicz, Robert, 2014, Redescription of the phytosaurs Paleorhinus ('Francosuchus') angustifrons and Ebrachosuchus neukami from Germany, with implications for Late Triassic biochronology, pp. 155-208 in Zoological Journal of the Linnean Society 170 (1) on page 163, DOI: 10.1111/zoj.12094, http://zenodo.org/record/530086
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