In 2024, researchers from the universities of Oxford and Birmingham excavated a huge expanse of a quarry floor in Oxfordshire filled with hundreds of dinosaur footprints.
Authors
- Kirsty Marie Edgar
Professor of Micropalaeontology, University of Birmingham
- Duncan Murdock
Collections Manager, Earth Collections, Museum of Natural History, University of Oxford
Dating to the Middle Jurassic period (around 166 million years ago), the extensive trackways are part of what has been described as a huge "dinosaur highway". They form the largest dinosaur tracksite in the UK today. It's among the largest in the world.
The tracks were made as dinosaurs walked across mudflats surrounded by warm tropical lagoons. As the feet of the giant animals, some up to 10 tonnes, pressed on the mud, they left behind both an impression of the foot and in some cases a large rim of displaced mud around the track.
The surface was then rapidly flooded and the tracks were filled in and buried by a clay-rich mud, which acted to preserve them. Over time and further burial these sediments turned into rock. Unlike body fossils, tracks give us a glimpse into a moment in the life of the dinosaur.
The size, shape and position of the tracks can tell us how these dinosaurs moved, their body size and speed, where they lived, and how they interacted with their environment and with each other.
Smaller finds, including shells, teeth and plant matter, help to build a more complete picture of this lost environment of Middle Jurassic Oxfordshire.
How it began
Dinosaur science itself began with the discoveries of fossil bones in Oxfordshire and recognition that they belonged to new creatures. Megalosaurus , an apex predator in the Middle Jurassic, was the first dinosaur to be scientifically named and described in 1824 from fossils found in slate quarries in the village of Stonesfield.
Remains of three other dinosaurs are also known from sites in the county, including the 18m-long sauropod Cetiosaurus.
In 1997, extensive trackways were discovered in Ardley Quarry, north Oxfordshire, including those likely belonging to the large carnivorous dinosaur Megalosaurus - a member of a dinosaur grouping known as theropods - as well as numerous larger tracks made by sauropods. These trackways were recorded and then reburied for the construction of an energy recovery facility.
Further discoveries at the smaller Ardley North quarry led to the trackway's surface being designated as a site of special scientific interest in 2010, in light of a planned extension of quarrying activity into the neighbouring Dewars Farm.
Early in 2022, quarry worker Gary Johnson felt "unusual bumps" as he was stripping back a layer of clay from the ground in his digger to expose the rocky quarry floor. On inspection he realised that these were regularly spaced and could be a trackway.
Dewars Farm and Duns Tew quarry manager, Mark Stanway, contacted the Oxford University Museum of Natural History. As more and more of the surface was exposed, the significance of the site became clear and, in collaboration with University of Birmingham and quarry operators Smiths Bletchington, a plan was formed for a major excavation.
In June 2024, together with Dr Emma Nicholls from the Oxford University Museum of Natural History and Professor Richard Butler from the University of Birmingham, we led a team of more than 100 staff, students and volunteers for a week long excavation of the quarry surface.
Together, we painstakingly uncovered and cleaned out the overlying clay from around 200 footprints, took more than 20,000 images of individual footprints for photogrammetry - a technique that uses photographs to create 3D models of objects and landscapes. Using computer software, we were then able to build detailed 3D models of the site using aerial drone photography - documenting the footprints in unprecedented detail for future research.
We identified at least five separate trackways. One of these was probably made by Megalosaurus and four by giant herbivorous sauropod dinosaurs. The longest trackway stretches for more than 150 metres.
Further excavations
Data analysis continues, but the trackways are already yielding insights into how these dinosaurs moved - including their speeds, how large they were and if and how they interacted. Each Megalosaurus track (a classic three-toed track) is around 65cm in length, with a stride length of about 2.7 metres and the dinosaur could have been up to 9 metres in length.
The sauropod tracks may have been made by a dinosaur called Cetiosaurus , reaching up to 18 metres in length, and weighing 10 tonnes or more. The longest sauropod trackway at Dewars Farm has tracks that are up to one metre long but the different trackways have tracks of different sizes indicating different species or different-sized individuals at the site. The spacing of the prints suggest that the sauropod and Megalosaurus were walking at similar speeds, about 5km per hour - roughly an average adult human walking speed.
Where trackways intersect, we can determine which animal passed through the area first. In this case, the theropod came after the sauropod, whether it was mere moments, days or weeks between these tracks, we don't know.
Dewars Farm is still a working quarry with no public access and will remain so in the medium term. However, we are actively working with Smiths Bletchington and Natural England on options for preserving the site for the future. Perhaps most exciting is that the ongoing quarrying of the overlying limestone (for use as crushed and graded aggregate) will only uncover more of the trackway surface.
We are further planning exploratory visits and hope to return for another excavation in summer 2025. It is very likely that the number, length and extent of the trackways will only increase and there may well be unexpected discoveries still to come.
Funding for the 2024 excavation was provided by the Curry Fund of the Geologists' Association (to Butler, Edgar, Nicholls & Murdock), the Research Support Fund of the School of Geography, Earth and Environmental Sciences at the University of Birmingham (to Butler and Edgar), and the Alumni Fund of the University of Birmingham (to Edgar and Butler).
Duncan Murdock does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
