Quarry's
fossils could help solve a 5 million-year-old mystery.
By Kevin Kilbane
of The News-Sentinel
Thu, Jul. 03, 2003
James Farlow cradles a huge molar in
his hand, a clue in what is a 5 million-year-old
mystery.
The tooth -- about the size of a peach
-- is a detailed cast, or replica, of a fossilized molar found
in the red clay soil under his feet.
The real tooth
belonged to a teleoceras, a squatty rhinoceros that stood 3 feet to 4 feet
tall and weighed about 300 pounds.
"
Imagine a very fat rhino that wants to be a dachshund," jokes Farlow,
a dinosaur expert at Indiana University-Purdue University Fort Wayne.
Farlow's
tone turns serious as he discusses the importance of the tooth and
other fossils found over the last five years at the Pipe Creek Junior quarry
southwest
of Marion. He says the site is the first in the eastern United States to
offer a glimpse of what life was like here between the Age of Dinosaurs,
which ended
65 million years ago, and the Ice Age, which began 30,000 years ago.
"
It (the quarry) tells us something about animals in North America from
a time we simply knew nothing about," says Farlow, who received
a $150,000 National Science Foundation grant to study the site. "It
is not simply important for the state, it is nationally and internationally
important."
The fossilized bones found from rhinos,
camels, bears and wild dogs raise many questions: Did the animals
wander in and die
at what apparently
was a marsh
or pond? Were they ambushed by predators lurking in the lush vegetation?
Or does
the failure to find a complete skeleton -- at least so far -- suggest
animals died above the sinkhole, that water later washed their remains
into the
low ground?
Farlow and other scientists believe
the answers to those and other questions still lie in the site's
unusual, reddish-brown
soil.
On a recent day, IPFW senior Tamra
Reece, 47, and members of an Indiana State Museum archaeological
crew stand shoulder-deep
in
a 2-foot-wide
trench in
the earth. The trench cuts across one side of the 200-foot-diameter
sinkhole, which
sat on the surface of limestone deposits some 5 million years ago.
Museum staff and volunteers shovel
excavated soil into 5-gallon buckets, which a lawn tractor hauls
up a crushed-stone ramp to
a service road
overlooking the site. At the edge of the road, museum staff and volunteers
dressed
in rain
gear
stand at large sieves, squirting water through excavated soil to separate
stone and fossils from sticky clay.
The sieves capture anything too
big to fit through a window screen. The particles, which can include
tiny bone fragments and rodent teeth,
then
go into bags
for closer scrutiny in Farlow's laboratory at IPFW or at the state
museum.
Quarry's rare finds
The stones
and pebbles tell a tale that actually began more than 400 million
years ago.
At that time, a shallow sea covered
most of what is now the Midwest, says Jack Sunderman, professor
emeritus of geology
at IPFW. Over millions
of
years, corals
and spongelike creatures known as stromotoporoids built up a mile-wide
reef at what is now the Pipe Creek Junior quarry.
After the sea receded
390 million years ago, the reef gradually turned into limestone
-- and a similar mineral, dolomite -- according to Sunderman,
who
has studied
the quarry's geology for nearly 30 years.
Five years ago, quarry workers
digging down to the top of the limestone bed unearthed an unusual
pocket of red, clay soil. Normally found only
in warm
climates, the
red clay resembles the soils of Georgia and other southern U.S. states.
Further study of the site led Sunderman
to develop this theory: Drainage of surface water or the flow of
an underground stream
slowly carved
a large cave
just below
the top of the former reef. Eventually -- he's not yet sure when --
the cave roof collapsed, creating a sinkhole.
Fossils of plants, frogs,
turtles and snakes suggest the sinkhole became a pond or marsh
surrounded by lush vegetation. The site attracted a
wide variety
of
animals.
Fossilized bones date to about 5 million
years ago, Farlow says. "
This is pretty rare stuff," notes Ron Richards, the state museum's
curator of paleobiology and natural history. Richards is helping to
coordinate the dig,
and fossils found eventually will go into the museum's collection.
Finds include bones from three species
of prehistoric camel. One camel stood as tall as a llama, Farlow
says. A second species stood slightly
taller,
while a third variety was long-necked and similar in size to a modern
giraffe.
Camels became extinct here just before
the Ice Age, Farlow says.
Other fossil discoveries include:
* A wild dog with large hyenalike jaws.
* A bear similar to the spectacled bear living today in the Andes
Mountains.
* A tortoise comparable in size to the Galapagos tortoise.
* Peccaries, which are related to wild pigs.
* Numerous squirrels, mice and other rodents, including four species
that had not been seen anywhere previously.
Farlow and the dig crew hope as-yet unturned soil may contain the
remains of a saber-toothed cat. That's the paleontologically correct
name for
a creature formerly known as a saber-toothed tiger.
Glimpse of the landscape
But it is not the fossils
themselves that most intrigue Farlow and Richards. It is the clues
they provide to what life was like
5 million
years ago
-- a page virtually blank in geologic history books for this part
of the country.
By comparing the growth rates of fossilized
turtle bones with growth rates of modern turtles, Farlow hopes
to learn
about the climate
and length of
the seasons
5 million years ago. Fast growth would suggest a warm climate and
long growing season.
Failure to find fossil evidence of
prehistoric horses, which roamed North America at that time, could
indicate
the sinkhole lay in a
forested area
rather than
on a grassy plain, Farlow says.
Using prior research on water's ability
to move bones, Farlow also hopes to determine whether rhinos, camels
and other large animals
died at the
sinkhole or whether
rain or streams washed in their remains after they perished nearby.
In addition, the cross-section of fossils found at the quarry provide
a rare, slice-of-life look at a small, prehistoric ecosystem, he
says.
"
That's what I enjoy -- looking for patterns and what they say about
this site and time," he adds.
Farlow and Richards, who will
complete the current dig Thursday, hope to finish all work at
the Pipe Creek Junior quarry next summer.
Because
of
other projects
and commitments, they and their crew work at the site only about
three weeks each summer.
The richness of the find, however,
has Farlow pondering whether similar fossil caches exist in other
limestone
deposits.
"
You wonder how many more of them are out there waiting to be found," he
says.
Boning up on prehistory
What: Some of
the 5 million-year-old fossils collected at the Pipe Creek Junior
quarry near Marion are on display in the "Missing Record" exhibit
at the Indiana State Museum in Indianapolis. The exhibit includes
a lifelike replica
of a teleoceras, a rhinoceroslike creature whose bones were found
at the quarry.
When: 9 a.m.-5 p.m. Monday-Saturday;
11 a.m.-5 p.m. Sunday.
Where: 650 W. Washington St., at White
River State Park in downtown Indianapolis.
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