18 dic 2012
A University of Nevada, Las Vegas research team recently unearthed
fossil remains from an extinct wolf species in a wash northwest of Las
Vegas, revealing the first evidence that the Ice Age mammal once lived
in Nevada.
The metapodial, or foot bone, was uncovered late last year by UNLV
geologist Josh Bonde during a survey of the Upper Las Vegas Wash. They
have now confirmed that the bone comes from a dire wolf.
The discovery site is near the proposed Tule Springs Fossil Beds
National Monument, a fossil-rich area known for its diversity and
abundance of Ice Age animal remains. Scientists estimate the fossil to
be 10,000 to 15,000 years old during the Late Pleistocene period.
"Dire wolves are known to have lived in almost all of North America
south of Canada, but their historical presence in Nevada has been absent
until now," said Bonde, a UNLV geology professor. He was a Ph.D.
student at the university when he discovered the bone.
"The Tule Springs area has turned up many species, but it's exciting
to fill in another part of the map for this animal and reveal a bit more
about the Ice Age ecosystem in Southern Nevada."
The dire wolf, a larger relative of the gray wolf, was present in
much of North and South America for more than a million years.
Scientists theorize that competition from other wolf species and a
possible food scarcity led to its extinction roughly 10,000 years ago.
Foot bones of the extinct dire wolf are difficult to distinguish from
those of the gray wolf. Researchers conclude bone is likely from a dire
wolf because of the abundance of dire wolf fossils―and scarcity of gray
wolf fossils―in similar-aged excavation sites throughout the Southwest.
Fossil remains of dire wolves are abundant in the La Brea tar pits
and have been found in other Southwestern states. Many of the same
species of Ice Age animals found at La Brea have also been recovered in
the Las Vegas Valley, including Columbian mammoths, camels, horses,
bison, and ground sloths.
"This discovery helps flesh out Southern Nevada's Pleistocene
ecosystem and shows that there are still important discoveries to be
made in the Upper Las Vegas Wash," said UNLV geology professor Steve
Rowland, a collaborator with Bonde on the study of local Ice Age
fossils. "To understand why certain species became extinct and others
did not, we need to learn as much as possible about predatory habits and
which species were especially sensitive to changes in the environment."
The announcement comes on the heels of a recent discovery in the same
wash of a saber-tooth cat by researchers from the San Bernardino County
Museum. Like dire wolves, saber-tooth cats were Pleistocene predators
that had been conspicuously absent from the Southern Nevada fossil
record.
According to Rowland, Tule Springs was a spring-fed, swampy area
during periods of the Late Pleistocene, an ideal spot for plant-eating
animals and their carnivorous predators.
The recent discoveries come exactly 50 years after scientists
conducted a 'big dig' at Tule Springs, revealing the site to be rich
with Ice Age fossils.
"Tule Springs likely had the highest density of large animals in the
area during the Late Pleistocene, and the marshy environment was very
good for preserving at least some of the bones and teeth of animals that
died there," said Rowland.
"In the 50 years since the 'big dig,' the scientists have confirmed
that humans interacted with Ice Age animals. We now have a new list of
questions about life and death in the Pleistocene, and a new tool kit of
research techniques to help us get the answers."
The identity of the find was confirmed by Xiaoming Wang of the Los
Angeles County Museum of Natural History, an expert on extinct species
of the dog family. Bonde has been surveying the Tule Springs area since
2007, and he and a group of UNLV undergraduate studentss are prospecting
for more fossils.
The center of the original 'big dig' is on the same parcel of land where Bonde discovered the wolf fossil.
The dire wolf bone, in addition to other bones collected by UNLV researchers, are cataloged, studied, and stored at UNLV.
