Dinosaurs could swim!
 Q: Your article about swimming ostriches got me
wondering. Could Tyrannosaurus Rex swim? You mentioned they
had light bones, sort of like birds. Greg, La Mirada, California
A carnivorous, large dinosaur swimming 125 million years ago. The cutaway
drawing shows the dinosaurs legs paddling below the water's surface. Only
his head and back stay above the water. Sketch courtesy of artist Guillaume Suan of
the University Lyon1, France, copyright , used with permission.
A: It's a warm, muggy day about 125 million years ago (early Cretaceous
period) when dinosaurs roamed the land and flew the skies of what is now
northern Spain.
The air is full of squawks and songs of dinosaurs. Birds
add their calls to the cacophony, as they flit among tall cyads, which crowd the shore of a vast lake.
A pack
of large, swift Utahraptor dinosaurs mill on the shore, sniffing to catch
scent of likely prey. A female catches a faint
whiff of a herd of lumbering Iguanodons,
and darts after them. Four follow, but the fifth gets distracted.
Ute, a young 20-foot (6-m) male nearest the lake, sees a huge pterosaur, diving low right at
him. Ute leaps to snag her with curved talons, but misses. The
pterosaur squawks her outrage, tilts her wings, and soars out to an
island breeding ground.
Ute roars, bounds after her and splashes into the lake, upright on his two
powerful hind legs. He soon realizes she's outdistancing him, but young
and curious, he follows anyway. At first, he wades, but, as the
ground drops away, water covers more of his body, buoying him, so his feet
barely touch. Gigantic claws on his hind feet gouge deep tracks in
the mud. Then he can touch no more.
He's swimming. The offshore current catches him, and tends to sweep him
left. Ute crabs right, and trails the flyer on a direct path to the
island. He swims steadily, paddling with his hind legs like a duck.
In about a half hour, Ute makes land.
It's a dino's dream! Thousands of pterosaurs roosting, waiting to be
harvested.
 One
of the dinosaur's claw prints, fossilized in the solidified offshore sediment of
the former lakebed. The 4-inch (10-cm) black bar shows the scale.
Photo courtesy of Loïc Costeur of the Université de Nantes, France, copyright,
used with permission.
This fictional scenario is based on scientific findings. A team of
paleontologists, lead by Rubén Ezquerra, found a set of twelve fossil claw
prints forming a 50-foot (15-m) long trackway in the solidified offshore
sediment of a former large lake in what is now northern Spain. The team
dated the tracks to the early Cretaceous period, about 125 million years ago.
"The tracks strongly suggest a floating theropod [a bipedal, lizard-hipped,
carnivorous dinosaur], clawing the sediment as
it swam in at most three meters (ten feet) of water," emails paleontologist Loïc
Costeur of Laboratoire de Planétologie et Géodynamique de Nantes, Université de
Nantes, France, one of the team. "The dinosaur swam with alternating
movements of the two hind limbs, a pelvic paddle motion, similar to those used
by modern bipeds, including aquatic birds." As in my scenario, the dinosaur
crabbed right to counteract a "leftward water current", and maintained his
chosen direction. In an article published in the June 2007 issue of Geology, the team concluded, the evidence "persuasively demonstrates that some
non-avian theropod dinosaur were swimmers." Furthermore, "they may well
have occupied hitherto unsuspected ecological niches."
Further Reading:
Ostriches swim! WonderQuest
Could a dinosaur scratch when he itched, and did he itch? WonderQuest
Did dinosaurs live in Antarctica? WonderQuest
Were
non-avian theropod dinosaurs able to swim? Supportive evidence from an
Early Cretaceous trackway,
Cameros Basin (La Rioja, Spain), by Rubén Ezquerra, Stéfan Doublet,
Loïc Costeur,
Felix Pérez-Lorente, Geology, June 2007, v. 35, no. 6, p. 507-510.
U
of Colorado researcher identifies tracks of swimming dinosaur in Wyoming,
University of Colorado
The
'inflatable' dinosaurs of the Mesozoic by Donald Henderson, University of
Calgary, NSERC
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(Answered Sep. 10, 2007)
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