By Kerry Sheridan
9 hours ago
Washington (AFP) - A
pint-sized tyrannosaur braved the frigid Arctic and feasted on fellow
dinosaurs 70 million years ago, according to a report Wednesday on a new
species identified from fossilized skull bones in Alaska.
Scientists have
crowned the fierce creature the "polar bear lizard," or Nanuqsaurus
hoglundi, and they say it stood as tall as a modern man but was half the
size of its very close cousin, T. rex, the "lizard king."
An
analysis of several skull bones and teeth are described in the journal
PLoS ONE by Anthony Fiorillo and Ronald Tykoski of the Perot Museum of
Nature and Science in Texas.
Roving across land that was dark for
half the year and prone to rainy, snowy and frigid spells, the miniature
tyrannosaur likely had a strong sense of smell and may also have had
sharp vision to hunt prey at night.It was also just as big as another common meat-eating dinosaur found in Alaska, the Troodon, Fiorillo told AFP.
"To us that is a really cool thing because it is telling us, we think, that there is something about the Arctic environment of 70 million years ago that selected for an optimal body size for a successful predator."
- Skull fragments tell a story -
The bones were found on a bluff above the Colville River in northern Alaska.
Remains
of the much larger T. rex have typically been found further south,
scattered across the western United States where the climate would have
been warmer.
The area inside
the Arctic Circle where the dinosaur bones were found was not as cold 70
million years ago, and was probably on par with modern day Seattle,
Washington, or Calgary, Canada.
The
tyrannosaur's skull fragments were found in a hole along with a horned
dinosaur it likely killed and tried to eat, based on the tooth-size
gashes in the plant-eater's bones, researchers said.
At the time of publication,
researchers had four bone pieces, some of which were crucial because
they showed the head growth of an adult, rather than a juvenile, and
allowed scientists to estimate the overall skull size.
Since then, more fragments have been unearthed, Fiorillo said.
"We
have a pretty complete picture of the skull roof now. The beauty of
that is that the sediment that filled it in preserves the shape of the
brain and we can see that this animal also had a well developed sense of
smell."
University of Chicago
paleontologist Paul Sereno, who was not involved in the research,
described the jaw and skull fragments as "pretty exciting."
When fossils of dinosaurs were first found in the Arctic three decades ago, they were initially mistaken for whale bones.
Early
on, some experts believed the dinosaurs may have migrated, or that
juveniles would have been unable to survive there, but more recent
discoveries have debunked those ideas.
"We
couldn't get ourselves to believe that they lived up there in the
darkness," Sereno told AFP, adding that recent discoveries have changed
that way of thinking.
"They must have been managing somehow. We know that reindeer change their diet to eat all sorts of strange things."
The
new species' name, Nanuqsaurus hoglundi, is a nod to the Inuit name for
polar bear, Nanook, and the natural gas tycoon Forrest Hoglund who
helped fund the Texas museum where Arctic dinosaur bones are displayed
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