Bold statement: A single coastal patch in central Bolivia now holds one of the richest fossil footprints catalogs in the world, redefining how we view dinosaur life and movement. And this is the part most people miss: the sheer scale and variety of tracks unlock a vivid storyboard of ancient ecosystems and social behavior that fossils alone rarely reveal.
Scientists have identified a record-breaking collection of fossilized dinosaur footprints and swimming traces at a national park in central Bolivia. The tracksite sits along a shoreline that once framed a dynamic coastline, with ripple marks running parallel to the footprints and other imprints in a northwest-southeast orientation, according to a new study. The majority of footprints belong to theropods—bipedal, three-toed carnivorous dinosaurs from the late Cretaceous period (about 145 to 66 million years ago). The researchers also documented numerous bird tracks, underscoring a diverse scene of life at the edge of the ancient sea.
In total, the team led by McLarty counted 16,600 theropod footprints and 1,378 swim tracks. These finds come from the Carreras Pampa tracksite, located within Torotoro National Park. Although the site was known, it had not been thoroughly studied or documented until now.
Carreras Pampa spans roughly 80,570 square feet (7,485 square meters) and was analyzed by first clearing debris and exposing the fossil impressions, then removing surrounding sediment to reveal additional tracks. The researchers noted a remarkable variety of footprint shapes and sizes, indicating that many theropod species roamed the ancient coastline. Some footprints measure under 4 inches (10 centimeters), a rarity in the fossil record, though it remains unclear whether they were produced by small theropods—for example Coelophysis—or by juvenile individuals of larger species.
The largest footprints exceed 12 inches (30 centimeters), which the team associates with mid-sized theropods such as Dilophosaurus or Allosaurus. By contrast, well-known large theropods like Tyrannosaurus rex and Giganotosaurus typically leave prints around 16 inches (40 centimeters) long.
Carreras Pampa stands out not only for the footprint count but also for the behaviors it captures. The site records a spectrum of locomotive actions, including walking, running, swimming, tail-dragging, and abrupt turning. According to McLarty, the preserve offers some of the most complete evidence of dinosaur tail traces anywhere and preserves multiple instances of unusual movement—providing a rare window into how these animals moved through wet, sediment-rich environments.
The swim traces themselves present as straight or comma-shaped grooves, often accompanied by one or two smaller grooves beside them. The primary groove is attributed to theropods dragging their middle toe across the mud at the water’s edge, while the auxiliary grooves likely come from the other toes. Unlike many other sites that capture only isolated swimming prints, Carreras Pampa preserves alternating left and right tracks, offering a more complete picture of swimming sequences.
The abundance and arrangement of impressions imply that Carreras Pampa functioned as a prehistoric highway, with parallel trackways suggesting groups or packs moving in concert at times. Bolivia’s track-rich landscape is a focal point for paleontologists seeking to understand dinosaur behavior and ecology.
"The tracksite with the next highest number of tracks is also in Bolivia," McLarty noted, highlighting Bolivia’s prominence as a dinosaur track hotspot. He contrasted Carreras Pampa with Cal Orck’o, a nearby tracksite etched into a nearly vertical quarry wall. While Cal Orck’o is long and narrow, Carreras Pampa occupies a broader, more expansive footprint, literally and scientifically.
Sascha holds multiple science journalism credentials and has contributed to outlets such as The Guardian and Zoe. In addition to writing, she enjoys tennis, baking bread, and browsing second-hand shops for hidden treasures.
Would you like to dive deeper into how paleontologists distinguish different dinosaur species from tracks, or explore what these footprints reveal about ancient ecosystems and group behavior?
