Ardley Quarry

(Dinosaur Paths)

Members of Oxfordshire Rigs, Oxfordshire Council and English Nature

(Left) Megalosaur footprints stretching for 180 metres.  (Right) Mike Windle with artists impression of Megalosaurus

Introduction

The rocks exposed in the quarry are 168 million years old limestone forming part of the White Limestone Formation of the Great Oolite Group which is middle Jurassic in age.  The limestone was deposited very near to the shore of a sea which shelved very gradually to the south-west.  To the east was low, forested land stretching away south-eastwards over London and towards Belgium.

The calm marine environment with little tidal influence produced mainly fine-grained, micritic sediment which was strongly bioturbated by a thriving population of bivalves, gastropods, echinoids and other benthos.  Small changes of sea level occasionally brought the mud banks above sea level.  One such horizon is represented by the floor of the quarry.  This bed is impressed with dozens of footprints of dinosaurs that walked across the sediment while is was still soft and wet.

The footprints form trackways made by two different dinosaurs.  The most numerous are the pothole-like impressions, 60cm across, of the feet of quadrupedal, herbivorous sauropods.  No skeleton remains have been found to identify the trackmaker but the most probably candidate is the 15 metre long Cetiosaurus whose bones occur in the White Limestone as several localities in the district.  The second type of trackway is made up of three-toed, bird-like footprints of a bipedal, carnivorous dinosaur.  These footprints are up to 80cm long and 2 metres apart.  The trackmaker was probably Megalosaurus, the only known theropod in the area of appropriate size and geological age.

Photo Gallery

Click on the photo's enlarge

Artwork by David M. Waterhouse

For more information visit about Ardley Quarry www.discoveringfossils.co.uk