Diminutive fleet-footed tyrannosauroid narrows the 70-million-year gap in the North American fossil record

Lindsay E. Zanno, Ryan T. Tucker, Aurore Canoville, Haviv M. Avrahami, Terry A. Gates, Peter J. Makovicky

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

To date, eco-evolutionary dynamics in the ascent of tyrannosauroids to top predator roles have been obscured by a 70-million-year gap in the North American (NA) record. Here we report discovery of the oldest Cretaceous NA tyrannosauroid, extending the lineage by ~15 million years. The new taxon—Moros intrepidus gen. et sp. nov.—is represented by a hind limb from an individual nearing skeletal maturity at 6–7 years. With a ~1.2-m limb length and 78-kg mass, M. intrepidus ranks among the smallest Cretaceous tyrannosauroids, restricting the window for rapid mass increases preceding the appearance of colossal eutyrannosaurs. Phylogenetic affinity with Asian taxa supports transcontinental interchange as the means by which iconic biotas of the terminal Cretaceous were established in NA. The unexpectedly diminutive and highly cursorial bauplan of NA’s earliest Cretaceous tyrannosauroids reveals an evolutionary strategy reliant on speed and small size during their prolonged stint as marginal predators.

Original languageEnglish (US)
Article number64
JournalCommunications biology
Volume2
Issue number1
DOIs
StatePublished - Dec 1 2019
Externally publishedYes

PubMed: MeSH publication types

  • Journal Article
  • Research Support, Non-U.S. Gov't

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