Bold opening hook: A single site in Bolivia has unlocked the most extraordinary dinosaur gathering ever seen, with a staggering 16,600 fossil footprints left by predators. But here’s where it gets controversial: what exactly do these tracks tell us about Late Cretaceous ecosystems and predator behavior?
What happened and where
Scientists have identified the world’s largest collection of dinosaur footprints at Carreras Pampa, a paleontological treasure in Torotoro National Park, Bolivia. The assemblage is remarkable for comprising 16,600 tracks, all attributed to theropods—the carnivorous relatives of Tyrannosaurus rex. This find is reshaping our understanding of how predatory dinosaurs lived and moved during the Late Cretaceous, just before their extinction.
Site highlights
Carreras Pampa stands out because its footprint record is dominated by carnivores, a contrast to many fossil sites that show a mix of meat-eaters and plant-eaters. The prints vary in size from under 10 centimeters to more than 30 centimeters, captured in Maastrichtian soils that preserve a snapshot of predatory life from the time.
Evidence of swimming and movement
Among the discoveries are 280 swim traces, 289 solitary footprints, and 1,321 continuous trackways tracing a single layered surface. In total, researchers documented more than 1,378 swimming footprints, some of which reveal alternating left-right limb movements, providing direct clues about how dinosaurs navigated water. This rare fossil record of aquatic locomotion was reported in Communications Biology and offers fresh perspectives on how these creatures traversed their watery environments.
Behavioral clues from the tracks
The Carreras Pampa footprints reveal intriguing details such as toe splay, tail drag marks, and subtle turns or pauses. The exceptional preservation—thanks to a carbonate-rich substrate and a low-energy depositional setting—allows researchers to interpret how larger theropods pressed into soft sediment and how smaller or lighter animals interacted with nearby terrain.
Ecological mystery: why predators only?
All identified tracks at Carreras Pampa belong to bipedal carnivores. The ecological reason for this predator-only congregation remains unresolved. Scientists offer several hypotheses—perhaps a hunting zone kept separate from prey, or a scavenging congregation gathered near a shrinking water source—but none fully accounts for the conspicuous absence of prey tracks across roughly 7,500 square meters. This mystery invites ongoing debate and further study about predator behavior and ecosystem structure during the end of the Cretaceous.
