South Dakota is home to an amazing number of archeological and paleontological sites, with more than 19,000 recorded. One of the most famous fossils unearthed in South Dakota is a 90% complete Tyrannosaurus rex—the most inclusive one ever discovered. 

The T-Rex was named Sue, and was found on the Cheyenne Sioux River Reservation near the small town of Faith, in the northwest corner of South Dakota. The fossil is estimated to be 67 million years old, and was discovered on August 12, 1990, by Sue Hendrickson.  T-Rex Sue is 42 feet long, and 12 feet high at her hips.  90% of the skeleton is original bone, missing only a foot, an arm, and a few ribs and vertebrae.  The original Sue is now housed at the Field Museum in Chicago, but the Washington Pavilion in Sioux Falls has a 40-foot T-Rex replica for visitors to explore.

Today, visitors to the state can observe archeologists and paleontologists in action at the following dig sites:

• Big Pig Dig, Badlands National Park: Discovered by hikers in 1993, Big Pig Dig is an active excavation site at The Badlands. Since its discovery, more than 13,000 bones have been removed from the site. Visitors to The Badlands National Park can visit The Big Pig Dig, and watch paleontologists hard at work.
• South Dakota Museum of Geology: Visit and participate in various digs throughout South Dakota. Sessions are two weeks in length and cost $450.00. 
• The Mammoth Site: The Mammoth Site in Hot Springs, South Dakota, is the world's largest mammoth research facility.  Visitors can tour an active archeological site and view Ice Age fossils as they are found.  Attractions at The Mammoth Site include a scientific excavation, an Ice Age exhibit hall, a walk-in mammoth bone hut, fun hands-on activities, a working paleontology laboratory, and a junior paleontologist dig.