A limestone cliff nearly a mile long at Cal Orck’o, outside Sucre, contains the largest collection of dinosaur tracks in the world: 12,092 footprints from nine distinct species, all dating back 68 million years.
The site was documented by a team led by Swiss paleontologist Christian Meyer, and Bolivia later submitted it to UNESCO’s Tentative List. These prints form 465 identifiable trackways.
No other site on Earth packs so many dinosaur ichnites — fossil footprints — into one place.
A Near-Vertical Wall That Was Once a Shoreline
The wall sits about 3 miles from downtown Sucre, inside a limestone quarry still operated by a French cement company.
Workers first noticed the markings in 1985, though the full surface wasn’t exposed until 1994, when mining operations removed a larger section of rock, revealing much of what’s visible today.
Some 68 million years ago, during the Late Cretaceous, this area was the shore of a vast lake.
Dinosaurs walked across wet mud and left impressions that hardened during dry spells. Layers of sediment then buried and protected them from erosion. The cycle repeated several times, which is why the wall today shows overlapping footprints at different stratigraphic levels.
Millions of years later, the uplift of the Andes tilted the once-flat ground to nearly vertical — an angle of almost 70 degrees.
The formation rises more than 330 feet and is part of the El Molino Formation, a geological unit that extends across much of Bolivia.
What the Tracks Reveal — and What They Don’t
Cal Orck’o preserves ichnites — impressions left by animals in motion, not skeletal remains.
From the shape and arrangement of those trackways, researchers identified at least nine kinds of dinosaur, including sauropods, theropods, ankylosaurs, ornithopods, and titanosaurs.
Among the most striking finds is a continuous trackway stretching several hundred feet, attributed to a juvenile tyrannosaur known informally as “Johnny Walker.” It ranks among the longest single dinosaur trackways ever recorded.
The way certain tracks are arranged also offers clues about how the animals behaved.
Because some trackways run parallel and close together, several researchers have suggested that different species were moving together along the same shoreline.
A Site Only Partially Protected
Cal Orck’o was designated a Paleontological Natural Monument of Bolivia in 1998 and has appeared on UNESCO’s Tentative List since 2003, under the name “Cal Orck’o: Footprints of Time.”
Even so, the nomination has never advanced to full inscription — in part because the site remains an active quarry.
Limestone extraction and the vibrations of heavy machinery continue to erode sections of the wall, and every so often, sections bearing footprints are lost before they can be documented.
The Parque Cretácico, which opened in 2006 next to the quarry, tries to make up for some of that loss. It offers guided tours and a museum with life-size replicas of the dinosaurs identified there, and the revenue helps fund continued documentation.
A Recent Moment in the International Spotlight
The site reached audiences beyond the scientific community through “One Strange Rock,” the National Geographic documentary series available on Disney+, which featured Cal Orck’o as an example of how a single rock formation can preserve a detailed record of an entire geological period.
The wall continues to erode.
Each rainy season strips away a little more than the last — and, now and then, uncovers a footprint no one had ever seen.
