Ancient mammals surface at dig
Volunteers comb site of 'Bones Galore' at Pawnee Grasslands
By Ann Schrader
Denver Post Science Writer
Thursday, August 23, 2001
Long before it was covered with grass, the present-day Pawnee National Grasslands was home
to tiny horses and deer, huge rhinos and pigs, and an odd camel or two.
Feeding the subtropical environment about 35 million years ago were river channels
carrying sediment from the last phase of mountain building 100 miles away. But then the
climate suddenly changed from greenhouse to near-desert, and the water holes started to
dry up.
Animals strong enough to move away slaked their thirst elsewhere, leaving behind the
vulnerable - the very old and the very young - trapped near shrinking water holes.
That's the ancient picture emerging as fossilized bones are dug out of an ancient water
hole on the undulating shortgrass prairie north of here at "Bones Galore."
Now in its fifth year of excavations, the Bones Galore site is yielding tantalizing pieces
of animals long gone from the face of the Earth.
"We're trying to understand what this area was like," said Russ Graham, curator
of earth sciences at the Denver Museum of Nature & Science. "We want to
understand the past, and we want to predict where to find the bones so the grassland can
be managed better."
Graham still wants to more precisely affix the date of the water holes. He also plans to
insert fossil information into software that can be manipulated in three dimensions for
further study.
A big part of the excavation, Graham said, "is community science, where we allow
people to participate in a research project."
Volunteers, students and staff from the museum and the U.S. Forest Service, which manages
the grassland, have unearthed parts of about 60 individual mammals.
Two years ago, a volunteer and his son discovered a complete skull of a brontothere - a
rhinoceroslike creature that was one-fourth to one-third larger than today's rhinoceros.
When discovered in 1996 by a Forest Service biologist, the site was white with bones on
the surface, hence its name "Bones Galore." Next year, the dig will be
completed, and Graham is looking for new excavation sites.
Up to two dozen workers have joined in on weekends during the two-week dig, with a handful
camping near the dusty draw during the week. They race into town for showers at the high
school and dine at the Prairie Station Cafe.
The volunteers delight in the scientific pursuit. Dan Smith came all the way from England
to get his hands dirty in the hot sun.
"I've found fragments, a couple of ribs and a complete vertebra," said Smith,
who learned of the opportunity online.
More typical of the volunteers and students in the museum's paleontology certification
program is John Davis. "I just got interested in paleontology," said the
eighth-grade science teacher at Sierra Middle School in Parker.
Davis has been videotaping the various steps in a dig - from the grunt work of removing
clay stone to preparing fossils for removal - to share with his classes.
END
OF REPORT
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