A new tyrannosaur with evidence for anagenesis and crocodile-like facial sensory system
Carr, Thomas D., Varricchio, David J., Sedlymeyer, Jayc C., Roberts, Eric M., and Moore, Jason R. (2017) A new tyrannosaur with evidence for anagenesis and crocodile-like facial sensory system. Scientific Reports, 7. 44942. pp. 1-11.
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Abstract
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.
| Item ID: | 48167 |
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| Item Type: | Article (Research - C1) |
| ISSN: | 2045-2322 |
| Additional Information: | 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/ © The Author(s) 2017 |
| Funders: | Channel 4, Carthage College, USA (CC) |
| Projects and Grants: | Dissertation Improvement Grant, CC Faculty Research & Development Grant |
| Date Deposited: | 03 Apr 2017 22:53 |
| FoR Codes: | 37 EARTH SCIENCES > 3705 Geology > 370506 Palaeontology (incl. palynology) @ 100% |
| SEO Codes: | 97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 100% |
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