Museum Staff in Race Against Time to Recover Fossils

A team of scientists from the Denver Museum of Nature and Science are embarking on a seven-week long expedition to recover the fossilised remains of American mega fauna discovered by chance last autumn at a construction site for an extension to the Ziegler reservoir near Snowmass village (Colorado).

The researchers have less than fifty days to recover the fossilised bones of animals such as ancient bison, Mastodons and Mammoths before the construction team have to move in to complete their work on extending the reservoir.  Ironically, the excavation work last year, revealed that the reservoir sat on the remains of an ancient Ice Age lake bed, one that had preserved as fossils evidence of the exotic life that once roamed this part of the United States.

In February, team members at Everything Dinosaur, reported on an agreement being reached between all parties to continue the research work: Scientists reach agreement over Ice Age dig site.

The team, in excess of thirty researchers intend to apply a methodical approach to surveying the site, last year, they had to work alongside the reservoir construction teams with their big diggers and machinery as the prehistoric animal remains were revealed.

Dr. Ian Miller, the museums curator of palaeontology stated:

“Last year, we were working in the same hole. It was a little more of a salvage operation.”

This time, there will be one backhoe, employed by the museum, to move the muck out of the way after it has been combed for fossils.  A small crew working on expansion of the reservoir will also be on hand, but off to the side of the fossil dig, not involved in it.

Predicting what will happen, Dr. Miller added:

“We will have thirty people shovelling this time, it’s going to be a little bit different than last year”.

Scientists and field workers, really put the town of Snowmass on the map when they  managed to collect some 600 bones and bone fragments last autumn, before snowfalls stopped their work.  The team found a treasure trove of ancient mammal remains including 15 elephant tusks.  The team found evidence eight to ten American Mastodons, four Columbian mammoths, two Ice Age deer, four Ice Age bison and one Jefferson’s ground sloth (the first ever found in Colorado).

Although limited by the need to complete the reservoir extension project, the Denver museum staff have it organised like a military operation with every contingency considered.  Over the summer, their numbers will swell as more volunteers and museum staff join the excavations.  In all, 36 scientists from 15 institutions and four countries will help analyse the Ice Age ecosystem preserved in the reservoir sediment.  For example, there will be a fossil pollen expert who takes sediment samples at every five centimetres of depth.  A sample the size of a sugar cube can contain 10,000 grains of pollen, this will give the scientists an ideal about the climate and how it changed as well as providing excellent data on the distribution and types of flora that were to be found at the site.

Remains of a Prehistoric Bison Found at the Reservoir

Picture Credit: Denver Museum of Nature and Science

Dr. Miller added:

“It really gives us a picture of that whole ecosystem.”

A much larger core sample, nearly one hundred kilogrammes of sediment, will be screened to search for evidence of microvertebrates, things like mice teeth and the vertebrae of tiny fish.

The researchers believe that Ziegler Reservoir dates from 150,000 years ago at its deepest layers, to about 50,000 years at the shallowest layers, a 100,000-year snapshot of the Ice Age as an ancient lake slowly filled in.

Because carbon dating can only date material out to about 45,000 years, other methods will be employed this year to date the various levels of the site, sophisticated techniques such as optically stimulated luminescence and cosmogenic exposure dating.

A skeleton museum crew will remain at Ziegler when dam construction begins, from July 2nd, just in case of new finds, but with the newly enlarged reservoir expected to be filled with water sometime this autumn, the next seven weeks will be crucial to recovering whatever secrets the site might yet yield.

The Denver museum is the repository for the specimens collected at Ziegler, and its preparation lab has been busy all winter preserving and cataloguing last year’s finds.  The laboratory will be closed during this year’s dig, though, as most of its staff will be in and out of the Snowmass site.

Most of the fossils found last year have been carefully dried; some are still in that process, according to a spokesperson for the project.  The horns and skull of an Ice Age bison have been assembled for display in the lab window, so some of the animals found are already being prepared for museum display.

The young, female mammoth known as “Snowy”, the first find at Ziegler, was lifted out of the earth last autumn, bone and matrix together, as winter closed in.  That fossil, each piece now carefully labelled, is about 60 to 70 percent complete, and this year’s dig will include efforts to find more of her remains, Dr. Miller stated.

The museum will create a cast of one of the fossils and turn it over to the Snowmass Water and Sanitation District, owner of the reservoir, for display. At some point, long after Ziegler is again a reservoir, an extensive exhibit of the fossils found  is likely, although it may not be a permanent feature of the museum.  It may even form part of a travelling exhibition so that more Americans can see the amazing fossils.

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