London, Nov 7 (IANS) An excavation site in western Colorado in the US has revealed an entire Ice Age ecosystem.

Denver Museum of Nature and Science excavation crews discovered two additional Ice Age mammal species at a fossil dig site at Ziegler Reservoir near Snowmass Village, Colorado last week.

The first find was a humerus, or upper arm bone, of a giant ground sloth. The second discovery was a small deer-like animal.

Partial remains of five mastodons, three Ice Age bison and a juvenile Columbian mammoth, as well as plant matter and insects, have also been found. Crews haven't uncovered any human artefacts, reports the Daily Mail.

Mammoths and mastodons are both elephant-like creatures with long tusks that both faded into extinction more than 12,800 years ago.

Speaking to CBC News, Ian Miller, the museum's curator of paleontology, said: "It is truly uncommon to get all parts of a fossil ecosystem preserved in one place.

"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."

A bulldozer operator who was working on a construction project at Ziegler Reservoir near Snowmass Village noticed what turned out to be rib bones sticking out of the ground while working in mid-October.

At first workers examined the bones thinking they were likely from a cow, but quickly noticed an 'enormous' jaw bone.

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