SNOWMASS VILLAGE.- Denver Museum of Nature & Science excavation crews discovered two additional Ice Age mammal species at a fossil dig site at Ziegler Reservoir near Snowmass Village, Colorado on Thursday. The first find was a humerus, or upper arm bone, of a giant ground sloth. The second discovery was a small deer-like animal. The total number of mammal species found at the dig site now totals five: Columbian mammoth, American mastodon, Ice Age bison, giant ground sloth, and the yet to be identified deer-like animal. When combined with the well-preserved plant matter, insects, and invertebrates found at the site, the excavation is revealing an exceptionally-well preserved Ice Age ecosystem.

"It is truly uncommon to get all parts of a fossil ecosystem preserved in one place," said Dr. Ian Miller, the Museum's curator of paleontology and chair of the Earth Science Department. "Instead of having just a piece of the ecosystem to tell the story, you've got all aspects of it. It's one of the most exciting scientific discoveries I've ever worked on."

Also on Thursday, Museum scientists determined there are two additional mastodons at the dig site after discovering a mastodon tooth and a leg bone in separate places. The discoveries bring the total number of partial mastodons found to five.

In another area of the dig site on Thursday, a Museum volunteer watching a bulldozer moving sediment spotted the horn of an Ice Age bison as it was churned up by the machine. The horn, along with additional bison bones found in two other locations, make scientists believe they have found parts of three Ice Age bison at the excavation site.

Construction crews working on the expansion of Ziegler Reservoir made the original discovery of a juvenile Columbian mammoth at the site on October 14. Over the weekend, Museum crews plotted a grid above the discovery and have begun a careful excavation of the area using archaeological techniques that remove sediment layer by layer. The material is then screened so workers can search for any evidence of human artifacts associated with the bones. Thus far, no evidence of human interaction with the Columbian mammoth has been found, though the excavation has uncovered additional portions of the animal.

There are four excavation crews working on recovering bones at the dig site right now. Another crew is focused on collecting plant matter found in a layer of peat, and they are making extraordinary discoveries.

All the plants recovered to date are still original material. Crews have found large logs, some up to three feet in diameter, where the grain and growth rings of the woods are easily seen. This will allow scientists to easily identify the species of the trees. Also, crews have recovered seeds, pollen, and leaves that are "mummified," where original organic material is preserved. Scientists also found preserved insects, some still iridescent, and a number of fossilized snails, which may tell them something about the water quality of the lake or bog where they lived thousands of years ago.

In order to ensure a thorough analysis of this Ice Age ecosystem, the Museum will enlist the assistance of top scientists in a number of specialties. Dr. Daniel Fisher, a paleontologist from the University of Michigan, will visit the excavation over the weekend. He has extensive experience excavating mastodon sites similar to the one in Snowmass Village. Dr. Fisher is an internationally renowned expert in mastodons, and is the guest curator for a traveling exhibition called "Mammoths and Mastodons: Titans of the Ice Age," which opened March 5, 2010, at The Field Museum of Natural History in Chicago.

Dr. Russ Graham, an Ice Age mammal specialist from Pennsylvania State University, and Dr. Greg MaDonald, a fossil sloth expert, will join the crew over the weekend. Other outside scientists will be consulted later in the excavation.

The Museum's excavation crew intends to work as quickly and efficiently as possible to remove as many fossils as they can before the heavy snowfall begins. Plans call for the crew to be at the site through the month of November, weather permitting.