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Phylogeny and evolutionary history of tyrannosauroid dinosaurs (free pdf)

Ben Creisler

A new paper in open access:

Stephen L. Brusatte & Thomas D. Carr (2016)
The phylogeny and evolutionary history of tyrannosauroid dinosaurs.
Scientific Reports 6, Article number: 20252 (2016)

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.