Description and Classification

Prestwichia footprints are classified as ichnites, a specific category within trace fossils. They represent the preserved impressions left by an animal moving across soft sediment, which later solidified into rock. The tracks assigned to Prestwichia are recognized as belonging to a bipedal (two-legged) dinosaur, almost certainly a type of theropod. Theropods were a large and diverse group of mostly carnivorous dinosaurs, which includes well-known members like Tyrannosaurus rex and Velociraptor, although the dinosaur that made the Prestwichia tracks would have been an earlier and probably smaller relative from the Middle Jurassic. The classification of ichnogenera like Prestwichia relies on careful comparison of footprint features (such as toe number, shape, and claw marks) with other known dinosaur footprints and with the foot anatomy of dinosaurs known from skeletal remains. It is important to understand that an ichnogenus such as Prestwichia identifies the trace fossil itself, not the specific biological genus of the dinosaur that created it, which often remains unknown.

Distinguishing Features

The features that distinguish Prestwichia are based on the morphology of the footprints themselves:

• Tridactyl form: The footprints typically show three main, forward-pointing toe impressions, a common characteristic of theropod dinosaurs.
• Claw impressions: Clear, often V-shaped or pointed marks at the tips of the toe impressions strongly suggest the presence of claws, which were typical for theropods.
• Digit proportions and arrangement: The relative lengths and widths of the toe impressions, the overall shape of the foot, and the angles between the digits are key diagnostic features.
• Bipedal gait: The tracks are found in sequences (trackways) that clearly indicate the animal walked on two legs. The spacing between prints (stride length) can provide estimates of the animal’s size and walking speed.
• Size: Prestwichia tracks generally indicate a medium-sized theropod for its time.

These characteristics help paleontologists differentiate Prestwichia from other dinosaur footprint ichnogenera found in Jurassic rocks, such as Grallator or Eubrontes, which might have been made by different types or sizes of theropods.

Paleoenvironment and Diet

The sedimentary rocks in which Prestwichia footprints are preserved, such as the Stonesfield Slate in England, offer insights into the paleoenvironment. During the Middle Jurassic, this region was characterized by shallow marine and lagoonal environments, with nearby landmasses supporting terrestrial ecosystems. The dinosaurs making these tracks likely walked along coastal plains, shorelines, or on exposed sediments in intertidal zones. The presence of theropod tracks like Prestwichia implies an ecosystem capable of supporting carnivorous animals. This means there would have been a variety of other creatures, including herbivorous dinosaurs (like early sauropods or ornithischians), smaller reptiles, and possibly early mammals, which could have served as prey for the theropod responsible for the Prestwichia tracks. While the footprints themselves do not directly reveal diet, the theropod trackmaker was almost certainly a carnivore, actively hunting other animals or scavenging.

Significance and Ongoing Research

Trace fossils like Prestwichia are highly significant because they provide direct evidence of dinosaur activity and behavior that skeletal fossils alone cannot offer. They can reveal how dinosaurs moved, their posture, estimates of their speed, and sometimes even suggest social behavior if multiple trackways are found together. Footprints are also crucial because they can be found in ancient environments where body fossils are scarce, thereby expanding our knowledge of dinosaur distribution and diversity. Ongoing research on Prestwichia and similar ichnofossils focuses on refining the identification of the specific types of dinosaurs that made these tracks. This involves detailed anatomical comparisons between the footprints and the foot structures of known dinosaur skeletons from the same geological period and region. Studying trackways also continues to contribute to broader understandings of dinosaur biomechanics and paleoecology. Discoveries of new Prestwichia sites or exceptionally well-preserved trackways could further illuminate the lives of Middle Jurassic theropods.