New megaraptorid (Dinosauria: Theropoda) remains from the Lower Cretaceous Eumeralla Formation of Cape Otway, Victoria, Australia

ABSTRACT

Megaraptorid theropods thrived in South America and Australia during the mid-Cretaceous. Their Australian record is currently limited to the upper Barremian–lower Aptian upper Strzelecki Group and the upper Aptian–lower Albian Eumeralla Formation of Victoria, the Cenomanian Griman Creek Formation of New South Wales, and the Cenomanian–lowermost Turonian Winton Formation of Queensland. The latter has produced Australovenator wintonensis, the stratigraphically youngest and most complete Australian megaraptorid. The Eric the Red West (ETRW) site on Cape Otway, Victoria (Eumeralla Formation; lower Albian), has yielded two teeth, two manual unguals, and a right astragalus that are almost identical to the corresponding elements in Australovenator. Herein, we classify these as Megaraptoridae cf. Australovenator wintonensis. We also reappraise the ‘spinosaurid’ cervical vertebra from ETRW and suggest that it pertains to Megaraptoridae. Three other theropod elements from ETRW—a cervical rib (preserving a bite mark), a caudal vertebra, and a non-ungual manual phalanx—are also described, although it is not possible to determine their phylogenetic position more precisely than Tetanurae (non-Maniraptoriformes). All elements were found in a fluvial deposit, associated with isolated bones of other theropods, ornithopods, and turtles, amongst others; consequently, no two can be unequivocally assigned to the same theropod individual. The new specimens from ETRW demonstrate that a megaraptorid theropod morphologically similar to Australovenator lived during the late Early Cretaceous in Victoria, at a higher paleolatitude than its northern counterpart. Moreover, they attest to the success of megaraptorids in late Barremian–early Turonian faunas throughout eastern Australia.

ACKNOWLEDGMENTS

The authors would like to thank all of those who have been part of the Dinosaur Dreaming crew at Eric the Red West; F. Karakitsos, L. Kool, A. Tait, W. Turner, W. White, and J. Wilkins for discovering and collecting the specimens described herein; L. Kool and the late D. Pickering for preparing the specimens; T. Ziegler (Melbourne Museum) for facilitating access to these specimens and for discussion regarding the possible bite marks; A. Gonzales and C. Paragnani for assistance with the photographs; B. Freshwater (St Vincent’s Hospital, Melbourne) for CT scanning the specimens; O. Panagiotopoulou (Monash University) for assistance with the processing of the CT and synchrotron data; The Paleontological Society for an Arthur James Boucot Research Grant (awarded to S.F.P. in 2017), which facilitated firsthand observation of the Australovenator type specimen; D. Elliott and T. Sloan (Australian Age of Dinosaurs Museum) for allowing access to the Australovenator type specimen in their care; the Winston Churchill Memorial Trust for a Churchill Fellowship (awarded to S.F.P. in 2017) that enabled firsthand observation of several Argentinian megaraptorid specimens; and R. Coria and L. Coria (Museo Municipal Carmen Funes), J. Calvo and J. Mansilla (Centro Paleontológico Lago Barreales), J. Porfiri and D. dos Santos (Universidad Nacional del Comahue), and R. Martínez and M. Luna (Universidad Nacional de la Patagonia San Juan Bosco) for allowing S.F.P. to make firsthand observations of Argentinian megaraptorid specimens in their care. The authors would also like to thank P. Bell (University of New England), F. Agnolin (Museo Argentino de Ciencias Naturales ‘Bernardino Rivadavia’), an anonymous reviewer, and editor L. Zanno for their constructive comments that greatly improved the manuscript.

ORCID

Stephen F. Poropat http://orcid.org/0000-0002-4909-1666

Patricia Vickers-Rich http://orcid.org/0000-0003-1850-8067