 Floating
dinosaur theory holds water
U
of C paleontologist studies buoyancy
of sauropods
by NSERC Newsbureau
They were the biggest animals ever to walk the earth.
And now the giant sauropod dinosaurs – known as “long-necks” to
millions of kids – have another claim to fame. They were also
the largest to ever float.
“
The sauropod dinosaurs were the colossal corks of the Mesozoic,” says
Donald Henderson (right), a postdoctoral researcher at
the U of C who teaches biology and conducts research with Faculty
of Science professor Anthony
Russell.
Henderson
presented his NSERC-funded discovery this month at the annual meeting
of the Society of Vertebrate Paleontology
in St. Paul, Minnesota.
While
it’s well known that many modern large animals can swim,
sauropods have long been viewed as bulky leviathans in a
class of their own. These giants tipped the scales at between
10 and 30 tonnes
and were up to 30 metres long and 12 metres in height.
Scientists
initially thought they were swamp waders, too huge to have survived
on land without crushing themselves.
In the 1950s, the theory changed; some thought a submerged
sauropod would
be covered with water to such a depth that the water pressure
wouldn’t
allow it to expand its lungs.
Recently,
evidence appeared that these heavyweights had bird-like lungs and
air sacs. Modern birds have a series of balloon-like
air sacs in their bodies that reduce their weight and aid
respiration.
Research
on sauropod vertebrae found the telltale marks of bird-like air
sacs. Scientists now think that sauropods were
full of air – at least 15 percent of their body volume was air
sacs.
“
Using 3-D computer modeling, I found that when you give sauropods
bird-like lung systems and air sacs they’re actually really
light . . . so they float really high in the water,” Henderson
says.
He made
the startling discovery using 3-D mathematical and computer models
of animal buoyancy.
The computer
modeling also indicates sauropods had a centre of balance above
their centre of buoyancy and so would have
been very unstable once afloat.
“
If they lost contact with the bottom they would tip sideways
and be in serious trouble,” he says.
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