Giant beavers had hidden talents
Skull passage may have helped extinct rodents sound off
partial airway doesn’t seem useful for
breathing, Rinaldi said. She and her
colleagues speculate that giant beavers
whooshed air through it to create sounds.
What those sounds were is another
puzzle. Her best guess, Rinaldi said, is
that the animal closed off the back of
the complete airway and forced a breath
through the dead-end passage. Air sped
up when pushed through the long narrow slit, and soft membranes there may
have created vibrations much like the
reed of a wind instrument.
The beaver’s sinuses could have given
considerable resonance to the sound,
as the enormous cavities extended over
the front of the brain and well into the
cheeks. Rushing whirs, rumblings or
maybe even whistles might have conveyed giant messages.
Today’s beavers aren’t much help in
re-creating the airway function because
they don’t have the skull structures of
By Susan Milius
Blessed with a hidden chamber in its
oversized skull, an extinct giant beaver
may have created a unique Ice Age call
of the wild.
Detailed CT scans reveal a dead-end
passageway leading from the back of
the animal’s skull toward its face. That
chamber connects via a long, narrow slit
to another passage going straight through
the beaver’s skull from throat to nose, vertebrate paleontologist Caroline Rinaldi of
the University of Missouri-Kansas City
School of Medicine reported November 2.
Estimates of how big the beaver
Castoroides ohioensis was range from a
sizable 60 kilograms on up to the bulk of
a modern black bear. The last giant beaver died roughly 10,000 years ago, about
the time many supersized creatures of
the last Ice Age went extinct.
The beaver’s closed-at-the-nose,
A replica of the interior of an extinct
giant beaver’s skull shows a blind
passageway (bottom) that may have
helped the animal produce sounds.
the extinct giants. “It’s a great lesson that
if you take a modern animal and scale it
up, you’d be wrong,” said rodent paleontologist Larry Flynn of the Peabody
Museum of Archaeology and Ethnology
at Harvard University.
New York City, who presented the findings November 3.
may have mixed
Supposedly separate types
may really have been one
“Woolly and Columbian mammoths
may be so close that they should really
be regarded as the same thing,” he said.
“One extraordinarily variable species.”
Both types of mammoths roamed
North America millennia ago. The
smaller woolly mammoth was thought
to have immigrated from Eurasia, while
the larger Columbian was considered
native to North America.
The new findings come from one well-preserved Columbian mammoth from
Utah, and a second, less well-preserved
one from Wyoming. DNA analysis placed
both on the same branch of the genetic
family tree as a subgroup of woollies.
The results have left MacPhee
“gobsmacked,” he said. “There will be
resistance to this conclusion because it
is so unexpected.”
By Susan Milius
The two major species of North American mammoth may have mated. DNA
analysis of the Ice Age beasts’ remains
suggests that the woolly mammoth
(Mammuthus primigenius) interbred
with what has been considered a separate, more southerly species—the
Columbian mammoth (Mammuthus
Two Columbian specimens turn out
to carry woollylike DNA inherited from
their mothers, said Ross MacPhee of the
American Museum of Natural History in
Unexpected indeed. “Whoa!” said
vertebrate paleontologist Russell
Graham of Pennsylvania State Univer-
sity, as he hunched over and clutched
his temples at the thought of combin-
ing mammoth species. He wants to see
a lot more DNA evidence from more
specimens, he said, but he relishes the
chance that something so seemingly
well-established as mammoth taxonomy
still holds surprises.
December 3, 2011 | SCIENCE NEWS | 13