Dozens of mammoths were trapped in a South Dakota sinkhole over 100,000 years ago. A bulldozer uncovered the first fossil 50 years ago, and experts have been finding bones ever since. The Mammoth Site ...

The institute is a hub for research, collection, preparation and mounting of dinosaur fossils, and minerals from the Black Hills region. Return to Rapid City for an evening at leisure.

Peter Larson, president of the Black Hills Institute of Geological Research, called the discovery "very significant." He said other mosasaurs have been found in South Dakota but nothing this complete.

Dozens of mammoths were trapped in a South Dakota sinkhole over 100,000 years ago. A bulldozer uncovered the first fossil 50 years ago, and experts have been finding bones ever since.