A team of scientists from the University of Nebraska, the American Museum of Natural History, the Berkeley Geochronology Center, and the Mongolian Technical University, presents new evidence in the cover story of the January issue of Geology that the dinosaurs and other ancient creatures from the Gobi Desert's richest fossil site were killed by sudden avalanches of water-soaked sand flowing down the sides of dunes. The research also revealed the first dinosaur footprints ever discovered in the Gobi Desert. The scientists, part of a joint expedition organized by the American Museum of Natural History and the Mongolian Academy of Science, were working in the area known as Ukhaa Tolgod (Brown Hills), one of the world's richest Late Cretaceous fossil sites.
Discovered by the American Museum/Mongolian Academy team in 1993, Ukhaa Tolgod is virtually unparalleled in the extraordinary preservation of the specimens it yields. Minuscule skeletal structures -- some of them smaller than one of the letters in this sentence -- are perfectly preserved. This remarkable quality of preservation indicates that the animals at Ukhaa Tolgod were killed swiftly by catastrophic events that buried their bodies before they could be scavenged or destroyed by the elements. It has often been presumed that immense sandstorms were the culprit, their wind-blown clouds of grit burying the dinosaurs alive. However the true nature of these disasters remained a mystery.
The geological detective work conducted by the authors of the new paper reveals that cause of death was actually a little-known and only recently recognized phenomenon, a debris flow, or "sand slide," in which a massive quantity of wet sand rushes down the side of a dune, burying everything in its path in an avalanche of debris.
Unraveling the mystery began with a detailed examination of the geology of Ukhaa
Tolgod. The team discovered that there were three distinct types of sandstones
at the site, each revealing
Contact: Elizabeth Chapman
American Museum of Natural History