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. 2016 Feb 2;6:20252.
doi: 10.1038/srep20252.

The Phylogeny and Evolutionary History of Tyrannosauroid Dinosaurs

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Free PMC article

The Phylogeny and Evolutionary History of Tyrannosauroid Dinosaurs

Stephen L Brusatte et al. Sci Rep. .
Free PMC article

Abstract

Tyrannosauroids--the group of carnivores including Tyrannosaurs rex--are some of the most familiar dinosaurs of all. A surge of recent discoveries has helped clarify some aspects of their evolution, but competing phylogenetic hypotheses raise questions about their relationships, biogeography, and fossil record quality. We present a new phylogenetic dataset, which merges published datasets and incorporates recently discovered taxa. We analyze it with parsimony and, for the first time for a tyrannosauroid dataset, Bayesian techniques. The parsimony and Bayesian results are highly congruent, and provide a framework for interpreting the biogeography and evolutionary history of tyrannosauroids. Our phylogenies illustrate that the body plan of the colossal species evolved piecemeal, imply no clear division between northern and southern species in western North America as had been argued, and suggest that T. rex may have been an Asian migrant to North America. Over-reliance on cranial shape characters may explain why published parsimony studies have diverged and filling three major gaps in the fossil record holds the most promise for future work.

Figures

Figure 1
Figure 1. The phylogenetic relationships of Tyrannosauroidea, based on parsimony analysis.
Strict consensus topology of five most parsimonious trees recovered from the cladistic analysis. Numbers by nodes indicate Bremer and jackknife support values. Thick lines next to each taxon depict temporal range, which in most cases is age uncertainty and not true range, and colors of lines denote geographic areas. Branches of the phylogeny are not scaled to time. Silhouettes are in relative proportion and scaled to total body length (T. rex = 13 meters). Geographic silhouettes from Loewen et al. and taxon silhouettes from phylopic.org (Kileskus: T.M. Keesey; Guanlong: S. Hartman; Yutyrannus: S. Hartman; Dilong: FunkMonk; Juratyrant: S. Hartman, T.M. Keesey; Eotyrannus: S. Hartman; Dryptosaurus T.M. Keesey; Albertosaurus C. Dylke; Nanuqsaurus J. Headden; Daspletosaurus S. O’Connor, T.M. Keesey; Tyrannosaurus S. Hartman).
Figure 2
Figure 2. The phylogenetic relationships of Tyrannosauroidea, based on Bayesian analysis. Bayesian consensus topology recovered from the cladistic analysis.
Numbers by nodes indicate posterior probabilities of each clade. All other conventions as in Fig. 1.

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