Cal Orck’o in Bolivia Has the Most Dinosaur Tracks at a Single Site – And It’s Almost Vertical!

Until the 1990s, the Dinosaur Plateau in Turkmenistan was thought to have preserved the largest concentration of dinosaur footprints in a single area. But then, deep in Bolivia, near the city of Sucre, one of the most extraordinary paleontological sites on Earth was discovered – Cal Orck’o. This massive limestone cliff holds what might be the most concentrated collection of dinosaur tracks ever discovered, with over 12,000 individual footprints preserved across 465 distinct trackways.

The most striking feature of Cal Orck’o isn’t just the sheer number of tracks – it’s their unusual, almost vertical orientation. The entire fossil bed sits at a dramatic 72-degree angle, creating a towering wall that stretches 1.5 kilometers (about a mile) in length and rises more than 100 meters (over 300 feet) into the sky.

But, of course, these tracks weren’t always vertical (gravity affected dinosaurs too). Their story begins 68 million years ago, during the Late Cretaceous period – just a few million years before the mass extinction event that would wipe out most dinosaur species.

The area was then part of Gondwana, the southern supercontinent, and Cal Orck’o itself was a flat, muddy plain beside a lake. Dinosaurs of various species left their footprints in the soft ground as they moved along the shoreline. The humid conditions caused their heavy feet to sink deeply into the mud, creating well-defined impressions.

The remarkable preservation of these tracks was thanks to a massive volcanic eruption that followed. Millions of cubic meters of ash rained down, blanketing the fresh footprints and protecting them from wind and rain that would have soon erased them. This natural layering protected the tracks from erosion, allowing them to fossilize over millions of years.

Over time, more sediment accumulated, and the immense pressure transformed these layers into rock. Then, as tectonic forces formed the Andes Mountains, the land was pushed upward, causing the once-horizontal track-bearing layers to tilt dramatically. Today, visitors can gaze up at this nearly vertical wall, where the tracks remain preserved, an impressive outcome of nature’s geological transformations.

The sheer number and density of footprints at Cal Orck’o make it one of the most significant dinosaur track sites on the planet. High-resolution mapping of this site revealed an astounding 12,092 individual tracks, representing at least nine different types of dinosaur tracks with 465 distinct trackways from a wide variety of dinosaurs.

Some of the most notable prints include the tracks of ankylosaurs (armored dinosaurs), ornithopods (plant-eaters that could walk on two or four legs), various types of theropods (meat-eating dinosaurs), and massive titanosaurs, which were among the largest dinosaurs to have walked the earth.

One of the most fascinating discoveries at Cal Orck’o is a set of tracks nicknamed “Johnny Walker” – the longest continuous dinosaur trackway ever found. These footprints, stretching an impressive 347 meters, were left by a young Tyrannosaurus rex.

The site spans approximately 65,000 square meters of rock face, documented through careful mapping conducted from 1998 to 2015. The diversity and quantity of tracks here are unparalleled, making Cal Orck’o a crucial resource for understanding dinosaur behavior and diversity in what is now South America.

What makes Cal Orck’o particularly valuable to scientists is how it preserves evidence of both solitary and group behaviors. Beside the solitary ones – such as limping, stopping, turning, spinning, running at different speeds, and individual hunting behaviors – some trackways suggest herding patterns among the giant sauropods, to whom about 26% of the trackways belong. Sauropods were the largest land animals that ever lived and included various types of titanosaurs that could weigh up to 100 tonnes.

Intriguingly, two distinct types of sauropod trackways are evident, each revealing different foot and toe impressions that may correlate with different species. Some tracks show broad, oval impressions, while others have a more rounded, horseshoe shape, with distinctive details that allow scientists to infer the species and behaviors of the trackmakers.

Cal Orck’o, which is often referred to as Bolivia’s “dinosaur dance floor,” offers an unparalleled look at the ancient world, showcasing not only the dinosaurs themselves but the environmental changes that reshaped their world. Yet, how long it will last remains uncertain. The site was first discovered in the 1990s by a mining company, and while mining operations in the area were terminated to preserve the site, natural forces like gravity, rain, and earthquakes continue to erode the limestone wall containing these ancient tracks. Without intervention, the wall is at risk of eroding entirely, potentially disappearing very soon.

Sources: 1, 2, 3, 4, 5