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The axial skeleton of Poposaurus langstoni (Pseudosuchia: Poposauroidea) and its implications for accessory intervertebral articulation evolution in pseudosuchian archosaurs

Dinosaurs and their close relatives grew to sizes larger than any other terrestrial animal in the history of life on Earth, and many enormous dinosaurs (e.g., Diplodocus, Spinosaurus, Tyrannosaurus) have accessory intervertebral articulations that have been suggested to support these large body size...

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Autores principales: Stefanic, Candice M., Nesbitt, Sterling J.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: PeerJ Inc. 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5816584/
https://www.ncbi.nlm.nih.gov/pubmed/29472991
http://dx.doi.org/10.7717/peerj.4235
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author Stefanic, Candice M.
Nesbitt, Sterling J.
author_facet Stefanic, Candice M.
Nesbitt, Sterling J.
author_sort Stefanic, Candice M.
collection PubMed
description Dinosaurs and their close relatives grew to sizes larger than any other terrestrial animal in the history of life on Earth, and many enormous dinosaurs (e.g., Diplodocus, Spinosaurus, Tyrannosaurus) have accessory intervertebral articulations that have been suggested to support these large body sizes. Some pseudosuchian archosaurs have been reported to have these articulations as well, but few have been characterized in these taxa because of a lower abundance of complete, three-dimensional pseudosuchian vertebral material in relation to dinosaurs. We describe the axial column of the large (∼4–5 m) poposauroid pseudosuchian Poposaurus langstoni from the Upper Triassic of Texas (TMM Locality 31025 of the Otis Chalk localities; Dockum Group, Howard County, TX, USA). P. langstoni was originally named from pelvic girdle elements and vertebrae; here we describe newly discovered and prepared presacral vertebrae and a presacral rib from the original excavation of the holotype in the 1940s. The well-preserved vertebrae have well-defined vertebral laminae and clear hyposphene–hypantrum intervertebral articulations, character states mentioned in pseudosuchians but rarely described. The new material demonstrates variation present in the hyposphene–hypantrum articulation through the vertebral column. We compared these morphologies to other pseudosuchians with and without the hyposphene–hypantrum articulation. Based on these careful comparisons, we provide an explicit definition for the hyposphene–hypantrum articulation applicable across Archosauria. Within Pseudosuchia, we find the hyposphene–hypantrum appeared independently in the clade at least twice, but we also see the loss of these structures in clades that had them ancestrally. Furthermore, we found the presence of large body sizes (femoral lengths >∼300 mm) and the presence of the hyposphene–hypantrum is correlated in most non-crocodylomorph pseudosuchian archosaurs with a few exceptions. This result suggests that the presence of the hyposphene–hypantrum is controlled by the increases and decreases in body size and not strictly inheritance.
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spelling pubmed-58165842018-02-22 The axial skeleton of Poposaurus langstoni (Pseudosuchia: Poposauroidea) and its implications for accessory intervertebral articulation evolution in pseudosuchian archosaurs Stefanic, Candice M. Nesbitt, Sterling J. PeerJ Evolutionary Studies Dinosaurs and their close relatives grew to sizes larger than any other terrestrial animal in the history of life on Earth, and many enormous dinosaurs (e.g., Diplodocus, Spinosaurus, Tyrannosaurus) have accessory intervertebral articulations that have been suggested to support these large body sizes. Some pseudosuchian archosaurs have been reported to have these articulations as well, but few have been characterized in these taxa because of a lower abundance of complete, three-dimensional pseudosuchian vertebral material in relation to dinosaurs. We describe the axial column of the large (∼4–5 m) poposauroid pseudosuchian Poposaurus langstoni from the Upper Triassic of Texas (TMM Locality 31025 of the Otis Chalk localities; Dockum Group, Howard County, TX, USA). P. langstoni was originally named from pelvic girdle elements and vertebrae; here we describe newly discovered and prepared presacral vertebrae and a presacral rib from the original excavation of the holotype in the 1940s. The well-preserved vertebrae have well-defined vertebral laminae and clear hyposphene–hypantrum intervertebral articulations, character states mentioned in pseudosuchians but rarely described. The new material demonstrates variation present in the hyposphene–hypantrum articulation through the vertebral column. We compared these morphologies to other pseudosuchians with and without the hyposphene–hypantrum articulation. Based on these careful comparisons, we provide an explicit definition for the hyposphene–hypantrum articulation applicable across Archosauria. Within Pseudosuchia, we find the hyposphene–hypantrum appeared independently in the clade at least twice, but we also see the loss of these structures in clades that had them ancestrally. Furthermore, we found the presence of large body sizes (femoral lengths >∼300 mm) and the presence of the hyposphene–hypantrum is correlated in most non-crocodylomorph pseudosuchian archosaurs with a few exceptions. This result suggests that the presence of the hyposphene–hypantrum is controlled by the increases and decreases in body size and not strictly inheritance. PeerJ Inc. 2018-02-14 /pmc/articles/PMC5816584/ /pubmed/29472991 http://dx.doi.org/10.7717/peerj.4235 Text en © 2018 Stefanic and Nesbitt http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ) and either DOI or URL of the article must be cited.
spellingShingle Evolutionary Studies
Stefanic, Candice M.
Nesbitt, Sterling J.
The axial skeleton of Poposaurus langstoni (Pseudosuchia: Poposauroidea) and its implications for accessory intervertebral articulation evolution in pseudosuchian archosaurs
title The axial skeleton of Poposaurus langstoni (Pseudosuchia: Poposauroidea) and its implications for accessory intervertebral articulation evolution in pseudosuchian archosaurs
title_full The axial skeleton of Poposaurus langstoni (Pseudosuchia: Poposauroidea) and its implications for accessory intervertebral articulation evolution in pseudosuchian archosaurs
title_fullStr The axial skeleton of Poposaurus langstoni (Pseudosuchia: Poposauroidea) and its implications for accessory intervertebral articulation evolution in pseudosuchian archosaurs
title_full_unstemmed The axial skeleton of Poposaurus langstoni (Pseudosuchia: Poposauroidea) and its implications for accessory intervertebral articulation evolution in pseudosuchian archosaurs
title_short The axial skeleton of Poposaurus langstoni (Pseudosuchia: Poposauroidea) and its implications for accessory intervertebral articulation evolution in pseudosuchian archosaurs
title_sort axial skeleton of poposaurus langstoni (pseudosuchia: poposauroidea) and its implications for accessory intervertebral articulation evolution in pseudosuchian archosaurs
topic Evolutionary Studies
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5816584/
https://www.ncbi.nlm.nih.gov/pubmed/29472991
http://dx.doi.org/10.7717/peerj.4235
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