"The discovery near Snowmass Village is one of those once-in-a-lifetime finds. Not only will it completely shape our understanding of life in the Rockies during the Ice Age, but it will become forever iconic for the kids of Colorado," said Dr. Kirk Johnson, the Museum's chief curator and vice president of the Research and Collections Division.
Construction crews working on the expansion of Ziegler Reservoir made the original discovery of a juvenile Columbian mammoth on October 14. After completing an agreement with the Snowmass Water and Sanitation District on October 29, Museum excavation crews arrived at Ziegler Reservoir on November 2 to begin digging for additional fossils. Over the next two weeks, they uncovered an exceptionally well-preserved Ice Age ecosystem that produced a bumper crop of Ice Age plants and animals. Excavation crews have recovered
- Eight to 10 American mastodons
- Four Columbian mammoths
- Two Ice Age deer
- Four Ice Age bison
- One Jefferson's ground sloth (the first ever found in Colorado)
- One tiger salamander
- Distinctly chewed wood that provides evidence of Ice Age beavers
- Insects including iridescent beetles
- Snails and microscopic crustaceans called ostracods
- Large quantities of well-preserved wood, seeds, cones, and leaves of white spruce, sub-alpine fir, sedges, seeds, and other plants
Though the discovery is barely a month old, the significance and uniqueness of the Ziegler Reservoir fossil site is readily apparent to scientists.
The high-altitude setting of this fossil site (8,874 feet) is consistently underrepresented in the Ice Age fossil record. "There have been suggestions that high-altitude environments might have harbored different communities, or had a different story of change, but since fossils representing them are so rarely found, no one has known for sure. Now is our chance to see what they are like," said Dr. Daniel Fisher, a mastodon expert from the University of Michigan, and a scientific consultant on the excavation.
In addition, it is exceedingly rare to discover so many different plants and animals from an Ice Age ecosystem in one place. Normally, scientists must piece together a picture of what plant and animal life was like in the Ice Age from many different sites. Here, they can assemble a very complete picture from one site.
The preservation of the fossils discovered at Ziegler Reservoir is exceptional. At least one of the tusks recovered from the site is still white after tens of thousands of years. Scientists think there is a good chance of recovering well-preserved ancient DNA from some of the fossils.
The age of the site is also of particular interest to scientists. Initial radiocarbon dating indicates that the Ziegler Reservoir site is more than 43,500 years old, and geologists estimate the site could be as old as 130,000 years. Additional analysis will provide more specific dating of the site. No matter what the result, the discovery of such an old Ice Age site is very rare and will provide scientists with an opportunity to learn about an earlier part of Ice Age history.
Finally, there are only a couple of other places in North America where such a great number of American mastodons are preserved in one place.
November 10 Snowmass Village Daily Update from DMNS on Vimeo.
Denver Museum of Nature & Science