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A new tyrannosaur with evidence for anagenesis and crocodile-like facial sensory system

A new species of tyrannosaurid from the upper Two Medicine Formation of Montana supports the presence of a Laramidian anagenetic (ancestor-descendant) lineage of Late Cretaceous tyrannosaurids. In concert with other anagenetic lineages of dinosaurs from the same time and place, this suggests that an...

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Autores principales: Carr, Thomas D., Varricchio, David J., Sedlmayr, Jayc C., Roberts, Eric M., Moore, Jason R.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5372470/
https://www.ncbi.nlm.nih.gov/pubmed/28358353
http://dx.doi.org/10.1038/srep44942
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author Carr, Thomas D.
Varricchio, David J.
Sedlmayr, Jayc C.
Roberts, Eric M.
Moore, Jason R.
author_facet Carr, Thomas D.
Varricchio, David J.
Sedlmayr, Jayc C.
Roberts, Eric M.
Moore, Jason R.
author_sort Carr, Thomas D.
collection PubMed
description A new species of tyrannosaurid from the upper Two Medicine Formation of Montana supports the presence of a Laramidian anagenetic (ancestor-descendant) lineage of Late Cretaceous tyrannosaurids. In concert with other anagenetic lineages of dinosaurs from the same time and place, this suggests that anagenesis could have been a widespread mechanism generating species diversity amongst dinosaurs, and perhaps beyond. We studied the excellent fossil record of the tyrannosaurid to test that hypothesis. Phylogenetic analysis places this new taxon as the sister species to Daspletosaurus torosus. However, given their close phylogenetic relationship, geographic proximity, and temporal succession, where D. torosus (~76.7–75.2 Ma) precedes the younger new species (~75.1–74.4 Ma), we argue that the two forms most likely represent a single anagenetic lineage. Daspletosaurus was an important apex predator in the late Campanian dinosaur faunas of Laramidia; its absence from later units indicates it was extinct before Tyrannosaurus rex dispersed into Laramidia from Asia. In addition to its evolutionary implications, the texture of the facial bones of the new taxon, and other derived tyrannosauroids, indicates a scaly integument with high tactile sensitivity. Most significantly, the lower jaw shows evidence for neurovasculature that is also seen in birds.
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spelling pubmed-53724702017-03-31 A new tyrannosaur with evidence for anagenesis and crocodile-like facial sensory system Carr, Thomas D. Varricchio, David J. Sedlmayr, Jayc C. Roberts, Eric M. Moore, Jason R. Sci Rep Article A new species of tyrannosaurid from the upper Two Medicine Formation of Montana supports the presence of a Laramidian anagenetic (ancestor-descendant) lineage of Late Cretaceous tyrannosaurids. In concert with other anagenetic lineages of dinosaurs from the same time and place, this suggests that anagenesis could have been a widespread mechanism generating species diversity amongst dinosaurs, and perhaps beyond. We studied the excellent fossil record of the tyrannosaurid to test that hypothesis. Phylogenetic analysis places this new taxon as the sister species to Daspletosaurus torosus. However, given their close phylogenetic relationship, geographic proximity, and temporal succession, where D. torosus (~76.7–75.2 Ma) precedes the younger new species (~75.1–74.4 Ma), we argue that the two forms most likely represent a single anagenetic lineage. Daspletosaurus was an important apex predator in the late Campanian dinosaur faunas of Laramidia; its absence from later units indicates it was extinct before Tyrannosaurus rex dispersed into Laramidia from Asia. In addition to its evolutionary implications, the texture of the facial bones of the new taxon, and other derived tyrannosauroids, indicates a scaly integument with high tactile sensitivity. Most significantly, the lower jaw shows evidence for neurovasculature that is also seen in birds. Nature Publishing Group 2017-03-30 /pmc/articles/PMC5372470/ /pubmed/28358353 http://dx.doi.org/10.1038/srep44942 Text en Copyright © 2017, The Author(s) http://creativecommons.org/licenses/by/4.0/ This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/
spellingShingle Article
Carr, Thomas D.
Varricchio, David J.
Sedlmayr, Jayc C.
Roberts, Eric M.
Moore, Jason R.
A new tyrannosaur with evidence for anagenesis and crocodile-like facial sensory system
title A new tyrannosaur with evidence for anagenesis and crocodile-like facial sensory system
title_full A new tyrannosaur with evidence for anagenesis and crocodile-like facial sensory system
title_fullStr A new tyrannosaur with evidence for anagenesis and crocodile-like facial sensory system
title_full_unstemmed A new tyrannosaur with evidence for anagenesis and crocodile-like facial sensory system
title_short A new tyrannosaur with evidence for anagenesis and crocodile-like facial sensory system
title_sort new tyrannosaur with evidence for anagenesis and crocodile-like facial sensory system
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5372470/
https://www.ncbi.nlm.nih.gov/pubmed/28358353
http://dx.doi.org/10.1038/srep44942
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