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Benoit J, Browning C, Norton LA. The First Healed Bite Mark and Embedded Tooth in the Snout of a Middle Permian Gorgonopsian (Synapsida: Therapsida). Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.699298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Despite their significance for paleobiological interpretations, bite marks have been rarely reported in non-mammalian therapsids (NMT). Here we describe, for the first time, the occurrence of a tooth embedded in the snout of a gorgonopsian. The tooth is surrounded by a bony callus, which demonstrates that the animal was still alive after the attack and healed. The identity of the attacker is unknown. Two hypotheses are discussed to account for this healed bite: failed predation (most likely by a biarmosuchian, therocephalian, or another gorgonopsian) and intraspecific social biting. Though predation cannot be ruled out, it has been hypothesized that gorgonopsians used their saber-like teeth for social signaling, which suggests that social biting may be the most likely scenario. The practice of social biting has long been hypothesized in NMT, but this is the first fossilized evidence of the behavior to be described.
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High frequencies of theropod bite marks provide evidence for feeding, scavenging, and possible cannibalism in a stressed Late Jurassic ecosystem. PLoS One 2020; 15:e0233115. [PMID: 32459808 PMCID: PMC7252595 DOI: 10.1371/journal.pone.0233115] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 04/28/2020] [Indexed: 11/19/2022] Open
Abstract
Bite marks provide direct evidence for trophic interactions and competition in the fossil record. However, variations in paleoecological dynamics, such as trophic relationships, feeding behavior, and food availability, govern the frequency of these traces. Theropod bite marks are particularly rare, suggesting that members of this clade might not often focus on bone as a resource, instead preferentially targeting softer tissues. Here, we present an unusually large sample of theropod bite marks from the Upper Jurassic Mygatt-Moore Quarry (MMQ). We surveyed 2,368 vertebrate fossils from MMQ in this analysis, with 684 specimens (28.885% of the sample) preserving at least one theropod bite mark. This is substantially higher than in other dinosaur-dominated assemblages, including contemporaneous localities from the Morrison Formation. Observed bite marks include punctures, scores, furrows, pits, and striations. Striated marks are particularly useful, diagnostic traces generated by the denticles of ziphodont teeth, because the spacing of these features can be used to provide minimum estimates of trace maker size. In the MMQ assemblage, most of the striations are consistent with denticles of the two largest predators known from the site: Allosaurus and Ceratosaurus. One of the bite marks suggests that a substantially larger theropod was possibly present at the site and are consistent with large theropods known from other Morrison Formation assemblages (either an unusually large Allosaurus or a separate, large-bodied taxon such as Saurophaganax or Torvosaurus). The distribution of the bite marks on skeletal elements, particularly those found on other theropods, suggest that they potentially preserve evidence of scavenging, rather than active predation. Given the relative abundances of the MMQ carnivores, partnered with the size-estimates based on the striated bite marks, the feeding trace assemblage likely preserves the first evidence of cannibalism in Allosaurus.
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Drumheller SK, Wilberg EW. A synthetic approach for assessing the interplay of form and function in the crocodyliform snout. Zool J Linn Soc 2019. [DOI: 10.1093/zoolinnean/zlz081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Abstract
Existing classifications of snout shape within Crocodylia are supported by functional studies, but ecological surveys often reveal a higher than expected diversity of prey items within putatively specialist groups, and research into bite force and predation behaviour does not always reveal significant differences between snout shape groups. The addition of more distantly related crocodyliforms complicates the ecomorphological signal, because these groups often occupy a larger area of morphospace than the crown group alone. Here, we present an expanded classification of snout shapes and diets across Crocodyliformes, bringing together geometric morphometrics, non-hierarchical cluster analyses, phylogenetic analyses, ancestral state reconstructions, ecological surveys of diet, and feeding traces from the fossil record to build and test predictive models for linking snout shape and function across the clade. When applied to living members of the group, these new classifications partition out based on differences in predator body mass and maximal prey size. When applied to fossils, these classifications predict potential prey items and identify possible examples of scavenging. In a phylogenetic context, these ecomorphs reveal differences in dietary strategies and diversity within major crocodyliform clades. Taken together, these patterns suggest that crocodyliform diversity, in terms of both morphology and diet, has been underestimated.
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Affiliation(s)
- Stephanie K Drumheller
- Department of Earth and Planetary Sciences, University of Tennessee–Knoxville, Knoxville, TN, USA
| | - Eric W Wilberg
- Department of Anatomical Sciences, Stony Brook University, Health Sciences Center, Stony Brook, NY, USA
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Affiliation(s)
- Stephanie K. Drumheller
- Department of Earth and Planetary Sciences, The University of Tennessee, 602 Strong Hall, 1621 Cumberland Avenue, Knoxville, TN 37996, USA
| | - James Darlington
- The St. Augustine Alligator Farm Zoological Park, 999 Anastasia Boulevard, St. Augustine, FL 32080, USA
| | - Kent A. Vliet
- Department of Biology, University of Florida, 208 Carr Hall, Gainesville, FL 32611, USA
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A Short-Snouted, Middle Triassic Phytosaur and its Implications for the Morphological Evolution and Biogeography of Phytosauria. Sci Rep 2017; 7:46028. [PMID: 28393843 PMCID: PMC5385495 DOI: 10.1038/srep46028] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 03/08/2017] [Indexed: 11/16/2022] Open
Abstract
Following the end-Permian extinction, terrestrial vertebrate diversity recovered by the Middle Triassic, and that diversity was now dominated by reptiles. However, those reptilian clades, including archosaurs and their closest relatives, are not commonly found until ~30 million years post-extinction in Late Triassic deposits despite time-calibrated phylogenetic analyses predicting an Early Triassic divergence for those clades. One of these groups from the Late Triassic, Phytosauria, is well known from a near-Pangean distribution, and this easily recognized clade bears an elongated rostrum with posteriorly retracted nares and numerous postcranial synapomorphies that are unique compared with all other contemporary reptiles. Here, we recognize the exquisitely preserved, nearly complete skeleton of Diandongosuchus fuyuanensis from the Middle Triassic of China as the oldest and basalmost phytosaur. The Middle Triassic age and lack of the characteristically-elongated rostrum fill a critical morphological and temporal gap in phytosaur evolution, indicating that the characteristic elongated rostrum of phytosaurs appeared subsequent to cranial and postcranial modifications associated with enhanced prey capture, predating that general trend of morphological evolution observed within Crocodyliformes. Additionally, Diandongosuchus supports that the clade was present across Pangea, suggesting early ecosystem exploration for Archosauriformes through nearshore environments and leading to ease of dispersal across the Tethys.
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Lessner EJ, Stocker MR, Smith ND, Turner AH, Irmis RB, Nesbitt SJ. A new rauisuchid (Archosauria, Pseudosuchia) from the Upper Triassic (Norian) of New Mexico increases the diversity and temporal range of the clade. PeerJ 2016; 4:e2336. [PMID: 27651983 PMCID: PMC5018681 DOI: 10.7717/peerj.2336] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 07/17/2016] [Indexed: 11/20/2022] Open
Abstract
Rauisuchids are large (2–6 m in length), carnivorous, and quadrupedal pseudosuchian archosaurs closely related to crocodylomorphs. Though geographically widespread, fossils of this clade are relatively rare in Late Triassic assemblages. The middle Norian (∼212 Ma) Hayden Quarry of northern New Mexico, USA, in the Petrified Forest Member of the Chinle Formation, has yielded isolated postcranial elements and associated skull elements of a new species of rauisuchid. Vivaron haydeni gen. et. sp. nov. is diagnosed by the presence of two posteriorly directed prongs at the posterior end of the maxilla for articulation with the jugal. The holotype maxilla and referred elements are similar to those of the rauisuchid Postosuchus kirkpatricki from the southwestern United States, but V. haydeni shares several maxillary apomorphies (e.g., a distinct dropoff to the antorbital fossa that is not a ridge, a straight ventral margin, and a well defined dental groove) with the rauisuchid Teratosaurus suevicus from the Norian of Germany. Despite their geographic separation, this morphological evidence implies a close phylogenetic relationship between V. haydeni and T. suevicus. The morphology preserved in the new Hayden Quarry rauisuchid V. haydeni supports previously proposed and new synapomorphies for nodes within Rauisuchidae. The discovery of Vivaron haydeni reveals an increased range of morphological disparity for rauisuchids from the low-paleolatitude Chinle Formation and a clear biogeographic connection with high paleolatitude Pangea.
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Affiliation(s)
- Emily J Lessner
- Department of Geosciences, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, VA, United States; Department of Biological Sciences, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, VA, United States
| | - Michelle R Stocker
- Department of Geosciences, Virginia Polytechnic Institute and State University (Virginia Tech) , Blacksburg, VA , United States
| | - Nathan D Smith
- The Dinosaur Institute, Natural History Museum of Los Angeles County , Los Angeles, CA , United States
| | - Alan H Turner
- Department of Anatomical Sciences, Stony Brook University , Stony Brook, NY , United States
| | - Randall B Irmis
- Natural History Museum of Utah, University of Utah, Salt Lake City, UT, United States; Department of Geology and Geophysics, University of Utah, Salt Lake City, UT, United States
| | - Sterling J Nesbitt
- Department of Geosciences, Virginia Polytechnic Institute and State University (Virginia Tech) , Blacksburg, VA , United States
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Drymala SM, Zanno LE. Osteology of Carnufex carolinensis (Archosauria: Psuedosuchia) from the Pekin Formation of North Carolina and Its Implications for Early Crocodylomorph Evolution. PLoS One 2016; 11:e0157528. [PMID: 27304665 PMCID: PMC4909254 DOI: 10.1371/journal.pone.0157528] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 06/01/2016] [Indexed: 11/18/2022] Open
Abstract
Crocodylomorphs originated in the Late Triassic and were the only crocodile-line archosaurs to survive the end-Triassic extinction. Recent phylogenetic analyses suggest that the closest relatives of these generally gracile, small-bodied taxa were a group of robust, large-bodied predators known as rauisuchids implying a problematic morphological gap between early crocodylomorphs and their closest relatives. Here we provide a detailed osteological description of the recently named early diverging crocodylomorph Carnufex carolinensis from the Upper Triassic Pekin Formation of North Carolina and assess its phylogenetic position within the Paracrocodylomorpha. Carnufex displays a mosaic of crocodylomorph, rauisuchid, and dinosaurian characters, as well as highly laminar cranial elements and vertebrae, ornamented dermal skull bones, a large, subtriangular antorbital fenestra, and a reduced forelimb. A phylogenetic analysis utilizing a comprehensive dataset of early paracrocodylomorphs and including seven new characters and numerous modifications to characters culled from the literature recovers Carnufex carolinensis as one of the most basal members of Crocodylomorpha, in a polytomy with two other large bodied taxa (CM 73372 and Redondavenator). The analysis also resulted in increased resolution within Crocodylomorpha and a monophyletic clade containing the holotype and two referred specimens of Hesperosuchus as well as Dromicosuchus. Carnufex occupies a key transition at the origin of Crocodylomorpha, indicating that the morphology typifying early crocodylomorphs appeared before the shift to small body size.
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Affiliation(s)
- Susan M. Drymala
- Research & Collections, North Carolina Museum of Natural Sciences, Raleigh, North Carolina, United States of America
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, United States of America
- * E-mail:
| | - Lindsay E. Zanno
- Research & Collections, North Carolina Museum of Natural Sciences, Raleigh, North Carolina, United States of America
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, United States of America
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Early crocodylomorph increases top tier predator diversity during rise of dinosaurs. Sci Rep 2015; 5:9276. [PMID: 25787306 PMCID: PMC4365386 DOI: 10.1038/srep09276] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 02/16/2015] [Indexed: 11/08/2022] Open
Abstract
Triassic predatory guild evolution reflects a period of ecological flux spurred by the catastrophic end-Permian mass extinction and terminating with the global ecological dominance of dinosaurs in the early Jurassic. In responding to this dynamic ecospace, terrestrial predator diversity attained new levels, prompting unique trophic webs with a seeming overabundance of carnivorous taxa and the evolution of entirely new predatory clades. Key among these was Crocodylomorpha, the largest living reptiles and only one of two archosaurian lineages that survive to the present day. In contrast to their existing role as top, semi-aquatic predators, the earliest crocodylomorphs were generally small-bodied, terrestrial faunivores, occupying subsidiary (meso) predator roles. Here we describe Carnufexcarolinensis a new, unexpectedly large-bodied taxon with a slender and ornamented skull from the Carnian Pekin Formation (~231 Ma), representing one of the oldest and earliest diverging crocodylomorphs described to date. Carnufex bridges a problematic gap in the early evolution of pseudosuchians by spanning key transitions in bauplan evolution and body mass near the origin of Crocodylomorpha. With a skull length of >50 cm, the new taxon documents a rare instance of crocodylomorphs ascending to top-tier predator guilds in the equatorial regions of Pangea prior to the dominance of dinosaurs.
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