Mastodon Fossils-Rare in Colorado-Donated to Denver Museum of Nature & Science

DENVER-October 1, 2009-Two young friends exploring a creek bed in Ken Caryl Ranch after a heavy rain over the summer inadvertently made a significant scientific discovery that informs the understanding of Colorado's prehistoric past.  Jake Carstensen and Tyler Kellett, both 13, stumbled across a rare mastodon mandible and tusk which could be 50,000 to 150,000 years old.  It is the best example of a mastodon ever found in Colorado, and only the third discovery on record in the state. Both the mandible and the tusk have been donated to the Denver Museum of Nature & Science by the Ken Caryl Ranch Master Association, the owner of the land where the discovery was made.

Carstensen and Kellett first discovered the mastodon mandible on June 1, 2009, while exploring a stream and pool of water after a period of heavy rain. The boys could tell right away they had found the jaw of some large animal because it contained a huge tooth. They brought their discovery home to determine what they had found. After quizzing Tyler Kellett's father, Don, a wildlife biologist, and ruling out every suggestion he made, the boys turned to the internet to find some answers. They quickly realized they had discovered the mandible of an American mastodon, a prehistoric relative of the elephant that went extinct approximately 13,000 years ago. The boys contacted Dr. Steve Holen, curator of archaeology at the Denver Museum of Nature & Science, who confirmed their conclusion.

Holen was immediately interested in the discovery because unlike mammoths, mastodon fossils are extremely rare in Colorado. With the help of Dr. Greg McDonald, a senior curator of natural history with the National Park Service and a Museum research associate, Holen learned that there were only two other instances of mastodon discoveries in Colorado on record-a tooth fragment was found northeast of Pueblo in 1875, and a full molar was found in Golden sometime prior to 1924 and donated to the Museum, which was known then as the Colorado Museum of Natural History.  
Holen returned to the area of the discovery with Carstensen and Kellett to do some additional exploration in early August, when they found the mastodon's tusk intact in a stream bank, submerged in water. With the blessing of the Ken Caryl Ranch Master Association, plans were made to temporarily divert the stream to excavate the tusk and determine whether any other parts of the mastodon skull were present.

The recovery of the tusk took two days to complete. On Saturday, September 19, Holen, along with Carstensen, Tyler and Don Kellett, and several other volunteers, began pumping water away from the stream bed around the tusk. The group returned on Sunday, September 20, once the water was diverted, and began the challenging, messy task of excavating the tusk. After digging carefully for several hours, the five-foot segment of tusk was unearthed, wrapped carefully in paper towels and plaster, and removed from the stream bed. No other signs of the mastodon's skull were found during the excavation.

At the Museum, volunteers cleaned the mandible and applied a preservative to prepare it for storage. The tusk is more fragile and will remain in its plaster jacket for several more weeks until it dries out, then it will undergo similar treatment.  The Museum has not yet determined whether the fossils will go on public display. With the completion of the donation, the mandible and tusk will be held in perpetuity as a part of Museum's permanent collection of 1.4 million objects.