Jurassic dinosaur tracks and trackways of the Cleveland Basin, Yorkshire: preservation, diversity and distribution

Abstract

SUMMARY Dinosaur tracks are abundant in the Middle Jurassic rocks of Yorkshire and indeed characterize the non-marine sequences developed within the Cleveland Basin. These tracks and associated trackways provide valuable evidence of the possible diversity of the dinosaur communities, their potential makers and behaviour and useful insights into the habitats and palaeoenvironment during the time of deposition. The uneven historical development of research into Yorkshire dinosaur tracks is reviewed and the Middle Jurassic lithostratigraphy, biostratigraphy and chronostratigraphy of the region is outlined. Next, the probable palaeoenvironment of the Middle Jurassic Cleveland Basin, generally regarded as a coastal plain and fluvial complex, is briefly summarized. The terminology used to describe the dominant preservational types of dinosaur tracks, such as surface, transmitted and underprints, is clearly defined, with examples from the Yorkshire sequences. The Yorkshire tracks show considerable morphological diversity and at present 29 different morphotypes have been recognized, which possibly represent at least 15 ichnotaxa. These morphotypes include both quadrupedal and bipedal forms, as well as a distinctive suite of raking prints resulting from swimming activity. The distribution and abundance of the known dinosaur tracks within the Middle Jurassic rocks of Yorkshire is described. For the first time, a range chart of dinosaur tracks is presented that illustrates the persistence of some morphotypes throughout the Ravenscar Group (Middle Jurassic) of the Cleveland Basin. Track distribution and diversity data allow reconstruction of the Yorkshire dinosaur communities that were made up of between 7–10 common types, belonging to sauropods, stegosaurids, ornithopods and theropods. The area is a ‘megatracksite’ of global importance.