|
Dec. 1, 2006
UI Museum Of Natural History Finds Third Ice Age Sloth
For over three years, students, staff and volunteers from the University of
Iowa Museum of Natural History (MNH), the UI Department of Geoscience, the
Department of Anthropology and the Office of the State Archaeologist have
been excavating the bones of a giant, SUV-sized, Ice Age sloth from a site
near Shenandoah, Iowa. In April 2006, they announced the discovery of a
juvenile sloth.
Today, the research team announced that diggers have unearthed the remains
of a second juvenile sloth.
"We've found only one bone so far, but it's unmistakably a third sloth and
unprecedented," said David Brenzel, curator of the UI Museum of Natural
History.
"It's like winning the lottery-twice," according to Dr. Holmes Semken,
professor emeritus of geoscience and co-leader of the sloth expeditions.
The scapula, or shoulder blade, recovered on the early November dig has been
confirmed as belonging to a very young individual of the same species
previously recovered, almost certainly less than one year old, according to
Greg McDonald, senior curator of natural history at the National Park
Service in Denver, Colo., and the world's foremost giant sloth authority. "I
never would have expected a second juvenile. We are in uncharted territory
with this new discovery."
"This one is a real baby," according to Sarah Horgen, MNH education and
outreach coordinator who uncovered the fossil, noting the bone is about
two-thirds the size of the two juvenile scapulae previously found. "I showed
it to Holmes, and he got very quiet. I think he went into shock," she said.
The team also recovered a complete hip bone and four or five ribs and
vertebrae from the older juvenile and a half-dozen other bones or pieces
still to be identified during the four-day dig. The site had previously
yielded almost 90 bones from the adult and more than 30 bones of the older
juvenile -- both ranking as the second-most complete skeletons of their kind
ever recovered and the first adult-juvenile combination ever found.
The discovery will force another rewrite of the grant proposal that Semken
is preparing for the National Science Foundation (NSF) to fund analyses of
the fossils.
"It's more important then ever that we try to prove this is a sloth family,"
said Semken, adding that he is assembling a team of university and national
experts to assist in the work. "The potential window this opens into the
family behavior of giant sloths is absolutely unique." The proposed research
has the potential to indicate the climate, local habitat, diet, dietary
deficiencies, some diseases and possibly the migration patterns for the
animals. Together, the three individual sloths may help establish parameters
for determining the sex of adults, age of sexual maturity, growth rates and
diet changes with age. "This is truly a Rosetta Stone for understanding
these rare and mysterious animals," said Semken.
Bob and Sonia Athen first discovered the sloth in the summer of 2001 behind
their home, along West Tarkio Creek, which forms the border between their
land and that owned by Dean and Loreta Tiemann of Lincoln, Nebraska. The
Athens subsequently brought their specimens to Iowa City, where Semken,
identified them as the remains of a Megalonyx jeffersoni, the giant sloth
discovered by and named in honor of Thomas Jefferson. Both families have
been enthusiastic donors and participants in the excavations.
A dozen of the bones are currently on display in the lobby of Iowa Hall.
Additional information about the sloth digs and research can be found on the
Museum of Natural History Web site at:
http://www.uiowa.edu/~nathist/Site/sloth/index.html
STORY SOURCE: University of Iowa News Services, 300 Plaza Centre One, Suite
371, Iowa City, Iowa 52242-2500.
END
|
