The phylogeny of Tetanurae (Dinosauria: Theropoda)

Abstract

Tetanuran theropods represent the majority of Mesozoic predatory dinosaur diversity and the lineage leading to extant Aves. Thus their history is relevant to understanding the evolution of dinosaur diversity, Mesozoic terrestrial ecosystems, and modern birds. Previously, the fragmentary and poorly sampled fossil record of basal (non-coelurosaur) tetanurans led to uncertainties regarding their basic interrelationships. This in turn prevented determining the relationships of many incompletely known taxa that nonetheless document a global radiation spanning more than 120 million years. We undertook an exhaustive examination of all basal tetanurans and all existing character data, taking advantage of recent discoveries and adding new morphological, temporal and geographic data. Our cladistic analysis of 61 taxa achieved significantly improved phylogenetic resolution. These results position several ‘stem’ taxa basal to a succession of monophyletic clades (Megalosauroidea, Allosauroidea and Coelurosauria). Megalosauroids include nearly 20 taxa arrayed amongst a basalmost clade (Piatnitzkysauridae, fam. nov.) and the sister taxa Spinosauridae and Megalosauridae; the latter includes two subfamilies, Megalosaurinae and Afrovenatorinae subfam. nov. Allosauroidea contains a diverse Metriacanthosauridae (= Sinraptoridae), Neovenatoridae, Carcharodontosauridae and a reduced Allosauridae. Finally, we assessed more than 40 fragmentary forms and hundreds of additional reported tetanuran occurrences. Tetanuran evolution was characterized by repeated acquisitions of giant body size and at least two general skull forms, but few variations in locomotor morphology. Despite parallel diversification of multiple lineages, there is evidence for a succession of ‘dominant’ clades. Tetanurae first appeared by the Early Jurassic and was globally distributed by the Middle Jurassic. Several major clades appeared prior to the breakup of Pangaea; as such their absence in specific regions, and at later times, must be due to poor sampling, dispersal failure and/or regional extinction. Finally, we outline a general perspective on Mesozoic terrestrial biogeography that should apply to most clades that appeared before the Late Jurassic.

Keywords:

• evolution
• systematics
• Mesozoic
• taxonomy
• morphology
• biogeography

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The phylogeny of Tetanurae (Dinosauria: Theropoda)

Acknowledgements

We would like to thank the many people who allowed us access to specimens in their care, including: Peter Wellnhofer (BSP); Rod Scheetz and Brooks Britt (BYU); Li Kui (CCG); Amy Henrici (CMNH); Kenneth Carpenter (DMNH); Dan Chure (DNM); William Simpson (FMNH); Wolf-Dieter Heinrich and David Unwin (MB); Zhao Xijin and Xu Xing (IVPP); John Foster (MWC); José Bonaparte, Alejandro Kramarz and Fernando Novas (MACN); Rodolfo Coria (MCF); Leonardo Salgado (MC); Diego Pol (MCF); Sean Duran (Miami Science Museum); Steve Hutt and Martin Munt (MIWG); Octavio Mateus (ML); Philippe Taquet, Daniel Goujet, Ronan Allain and Emily Long (MNHN); Rodolfo Coria (MPEF); Jorge Calvo (MUCPv); Juan Canale (MUCPv-Ch); Vince Schneider and Drew Eddy (NCSM); Jeff Person (OMNH); Paul Jeffery (OUMNH); Jaime Powell (PVL); Oscar Alcober and Ricardo Martínez (PVSJ); Jaime Powell (PVL); David Mullin (SDM); Rich Ketcham and Tim Rowe (TMM); Sandra Chapman, Angela Milner and Paul Barrett (NHM); Robert Masek and Paul Sereno (University of Chicago); Pat Holroyd and Kevin Padian (UCMP); Mike Getty (UMNH); and Guang-Zhou Peng (ZDM). In several cases, we were granted access to then-unpublished materials, for which we are particularly grateful. This paper benefited from numerous discussions with Jeffrey Wilson, Cathy Forster, Ron Tykoski, Paul Barrett, David Norman, and Nathan Smith, careful editorial work by Susannah Maidment, and detailed and insightful reviews by Oliver Rauhut and Stephen Brusatte.

Translations of Allain (2001), Bonaparte & Novas (1985), Bonaparte (1986), Depéret & Savornin (1925, 1928), Dong et al. (1983), Eudes-Deslongchamps (1837), Janensch (1925), Kurzanov (1989), Lapparent (1960), Nessov (1995), Novas (1991a,b, 1992), Powell (1979), Stromer (1915, 1931), Taquet & Welles (1977) and Thévenin (1907) are available at the Polyglot Paleontologist website (http://www.paleoglot.org/).

This research was supported by NSF DEB-9904045 to MTC and SDS; NERC studentship NER/S/A/2005/13488 to RBJB; and smaller grants from The Jurassic Foundation, SYNTHESYS and the Palaeontographical Society to RBJB.