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Largest Group of Trackways (and Two Eggs) Found in Bolivia August 15, 1998

The largest group of dinosaur trackways, containing hundreds of footprints, was found in the Andes mountains in Bolivia, South America, near the town of Sucre. These tracks date from the late Cretaceous period, about 65 to 70 million years ago, right before the large K-T extinction which ended the reign of the dinosaurs. The footprints include a lot of medium-sized sauropods (titanosaurs ) , some small- to medium-sized theropods, and other as yet unidentified dinosaurs (ornithopods, including ankylosaurs). The individual tracks are up to 3 feet (1 m) long.

The Swiss paleontologist Christian Meyer, who has been working at the site, says, "There is no comparable site in the world. ... The site covers an area of 269,100 square feet (25,000 sq meters)," Meyer said. One of the trackways extends up to 1,100 feet (350 m); this unbroken set of dinosaur footprints may be the longest yet found in the world.

The site is located in a limestone quarry and parts of the track are at angles up to 70° from horizontal. The tracks were made on an ancient lakebed that was flat during the late Cretaceous period but has been pushed up along with the Andes mountains and is now quite steep.

So far, the six sets of ankylosaur tracks have yielded the most surprising results so far. The ankylosaurs were apparently travelling at a pretty fast rate, which is not what was expected, given their massive bodies, heavy armor covering, and stubby legs. Other ankylosaur trackways (there are only about a dozen worldwide) show slow locomotion, but these Bolivian ankylosaurs were relatively speedy, as were the sauropods.

Two fossilized eggs from about 68 million years ago were also found. "We found two eggs that could be from dinosaurs," said Meyer, "Of the eggs we found, one measures 25 cm (10 inches) and the other, from a flying reptile, is big and measures 40 cm (16 inches)."

The site is 440 miles (700 km) southeast of La Paz, Bolivia and is at an altitude of 9,200 feet (2,800 meters). Other fossils have been found at the site, including crocodiles, fish, turtles, mollusks, actinopterygians (ray-finned fishes), charophytes (green algae), stromatolites (blue-green bacteria). Although the trackways were found in 1996, they were visited by paleontologists in 1998 and the analysis of these new fossils has just begun.

The wide range of late Cretaceous tracks at this site leans support to a quick, catastrophic extinction at the end of the Cretaceous, and not a gradual decline.

RELATED LINKS
Sedimentology, Stratigraphy and Ichnofacies of the El Molino Formation (Sucre, Bolivia)from Dr. Christian Meyer, Institute of Geology & Paleontology, Basel, Switzerland.

More information on trackways and other trace fossils.

A page on dinosaur locomotion

Information about Dinosaur eggs

Other fossils found in South America.

Chart of geological time

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