Saurischian dinosaur tracks from the Upper Triassic of southern Queensland: possible evidence for Australia’s earliest sauropodomorph trackmaker

Abstract

ABSTRACT Fossil footprints provide the only evidence of Triassic-aged dinosaurs in Australia. While historically several Triassic dinosaur tracksites are reported, only one specimen exists for direct study. Evidence for the Rhondda colliery (Ipswich) trackmaker, Upper Triassic Blackstone Formation as a very large-bodied Triassic predatory dinosaur is not supported by the present study because of overestimated footprint length measurements, and we question earlier interpretations that these tracks are Eubrontes-like. Instead, we recognise shared characteristics with the sauropodomorph ichnogenus Evazoum. The track morphology resembles that of Evazoum on account of the distinct shape and position of the impression of the metatarsophalangeal pad for digit IV. The mesaxony of the Blackstone Formation track is also low, but possibly slightly higher than in Evazoum, if the proportions of the digital impressions are correctly interpreted. Finally, the trackway pattern shows constant track inward rotation, a feature observed in typical Evazoum and mostly absent in Eubrontes. Therefore, we assign these Australian tracks as Evazoum ichnosp. indet. If our assessment of the Blackstone Formation tracks is correct, they provide the first and only evidence of basal sauropodomorph dinosaurs from Australia. In addition to this record, we give an overview of other reported (but lost) Australian Triassic dinosaur footprints.