An artist's rendering shows how the
fossilized remains of a Jurassic crocodile found in Oregon may have
appeared in water. (Livescience Photo) Photo
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BEIJING, March 22(Xinhuanet) -- The fossil of an ancient
amphibious reptile with a crocodile's body and a fish's tail has been unearthed
in U.S. Oregon.
Scientists believe the creature's remains were transported
by geologic processes nearly 5,000 miles away from where it originally died more
than 100 million years ago.
The new fossil is the oldest crocodilian ever
unearthed in Oregon and one of the few to be unearthed on this side of the
Pacific. The "hybrid" animal is thought to be a new species within the genus
Thalattosuchia, a group of crocodilians living during the age of dinosaurs.
The reptile roamed a tropical environment in Asia
about 142 to 208 million years ago. Called a Thalattosuchian, the amphibious
creature represents an early milestone in evolutionary history, marking a
transition during which these reptiles moved from being semi-aquatic to wholly
ocean species.
Scientists uncovered the remains of the six- to
eight-foot-long reptile in Jurassic rock on private property in the Snowshoe
Formation of the Izee Terrane, a rock formation in Oregon. They knew the croc
came from Asia due to distinct anatomical features, such as the way its ribs
were connected to the rest of its body.
The rock-entombed animal migrated eastward from
perhaps Japan via continental drift, a theory of land movement in geological
time, suggests William Orr, part of the fossil-discovery team and director of
the Thomas Condon State Museum of Fossils at the University of Oregon.
During ancient times, the Pacific Ocean was much
wider than it is today, and Orr suggests the rocky ride could have taken as long
as 100 million years before reaching North America.
Like modern-day crocodilians, the creature sported
both land-lubbing and ocean-faring equipment. It had short, stubby legs, which
the scientists say would have allowed it to creep easily along the ground and
lay eggs.
But the amphibious Thalattosuchia was also at home in
the water. With webbed feet and a fish's tail, the reptile was likely a swift
swimmer that could pulse through the water in search of aquatic prey.
"The thing that makes this creature unique is its
tail," Orr said. Unlike today's reptiles, the creature had a shark-like tail, an
indication of its ability to maintain itself in a marine environment.
"[The animal] was awfully close to being purely
aquatic," Orr said.