Reconstruction of Middle Jurassic Dinosaur-Dominated Communities from the Vertebrate Ichnofauna of the Cleveland Basin of Yorkshire, UK

Abstract

Globally, skeletal remains of dinosaurs are particularly rare throughout much of the Middle Jurassic. Thus, other sources of evidence, and most importantly ichnofaunas, are important indicators of the contemporary terrestrial vertebrate communities. The outcrops of the Ravenscar Group (Aalenian—Bajocian) within the Cleveland Basin of Yorkshire, UK, which have recently been recognised as a megatracksite of global significance, provide one such major source of ichnofaunal information of this age. A comprehensive database on the variety and occurrence of dinosaur and other vertebrate traces within the Ravenscar Group has been built from a long-term and detailed study of the sequence. Thirty different and distinct morphotypes of vertebrate traces have been recognised and are being analysed and further differentiated morphometrically. Some of the morphotypes represent behavioural, preservational and perhaps ontogenetic variants of other morphotypes, but nevertheless the range of quadrupedal and bipedal prints allows an overall fauna of sauropod, stegosaurian, ornithopod and theropod dinosaurs along with crocodiles, pond turtles and fish to be reconstructed. The distribution and abundance of prints and print types within the succession shows evidence of environmental control on the behaviour and distribution of the vertebrates. Case studies highlight both the advantages and disadvantages of this type of data in reconstructing palaeocommunities.

Keywords:

• Dinosaur tracks
• Middle Jurassic
• Ravenscar Group
• Cleveland Basin
• Yorkshire
• communities
• ichnofauna

ACKNOWLEDGEMENTS

The authors would like to thank all the many people who have taken an interest in their work and who have in many cases assisted in the field and helped to build the data on which this paper is based. In particular the authors are very grateful for the support of Earthwatch, both for its generous financial support and for the many enthusiastic volunteers who have taken part in our projects. We thank Simon Jackson for his comments and practical assistance, and Jim Booth and other past and present members of the Sheffield University Dinosaur Track Research Group. Technical help from Paul Coles, Rob Ashurst and Barry Pigott is gratefully acknowledged.