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10/26 Science News Dino Articles: Urination, Pterosaurs, Mosasaurs, Stegos
Several dino related articles in the 10/26. They're not available online
unless you're a subscriber, so I'll summarize.
Scientists say that a bathtub-shape depression found at one of North
America's most significant sites of dinosaur tracks is the first
recognized evidence of urination in dinosaurs.
... Katherine McCarville of the South Dakota School of Mines and
Technology in Rapid City.
Because the ancient lakeshore was nearly flat, the researchers contend
that dinosaurs were the only possible source of such concentrated fluid
streams. The size of the basin at the Colorado track site suggests that
one of the brontosaurs that strode across the area was the culprit, says
McCarville. She estimates that the behemoth's bladder held about 1,300
McCarville, K., and G.A. Bishop. 2002. To pee or not to pee: Evidence for
liquid urination in sauropod dinosaurs. Sixty-Second Annual Meeting of the
Society of Vertebrate Paleontology meeting. Oct. 9-12. Norman, Okla.
A study of the claws of ancient flying reptiles known as pterosaurs
suggests that some of the creatures may have walked like present-day
herons and used claws on their wings to hold prey.
...In modern birds, claw curvature is closely correlated with the animal's
behavior, says David A. Krauss...
Pterosaurs had claws both on their feet and on their wings. An analysis of
more than 100 museum specimens shows that the curvature of claws on
pterosaurs' wing fingers was, on average, comparable to that of perching
birds. Claws on the pterosaurs' feet, however, were almost straight, like
those of birds that walk on the ground. This combination hints that
pterosaurs didn't live in trees, says Krauss.
... Krauss and his colleagues contend that pterosaurs walked upright but
used their curved wing claws to hold prey steady while they consumed it.
Krauss, D.A., et al. 2002. Claw geometry is an indicator of the
terrestrial habits of pterosaurs. Sixty-Second Annual Meeting of the
Society of Vertebrate Paleontology. Oct. 9-12. Norman, Okla.
A mathematical analysis of a fossil stegosaur's bones leaves little
doubt that the creature's spike-studded tail was an effective defense
...Those pointy skewers, wrist thick at their base, projected backward and
almost horizontally from the sides of the tail at angles of about 35 and
60, says Frank Sanders of the Denver Museum of Natural History. ...
Sanders and his colleagues estimate that Stegosaurus could flex its tail
about 13 to the left or right but only a few degrees up and down. Despite
this limited range of motion, the animal's tail muscles probably could
accelerate the tail to strike with a force of about 35 kilograms. ...
it generates a pressure more than 1,000 times that of the atmosphere at
sea level. That's more than sufficient to puncture ...
Sanders, F., K. Carpenter, and L. McWhinney. 2002. Mechanics of stegosaur
tails as weapons: A mathematical analysis. Sixty-Second Annual Meeting of
the Society of Vertebrate Paleontology. Oct. 9-12. Norman, Okla.
Mosasaurs were prehistoric aquatic reptiles that cruised the world's
oceans for 30 million years or so before they and the dinosaurs on land
went extinct, about 65 million years ago. Newly discovered mosasaur
fossils suggest that the creatures gave birth in midocean, countering
previous theories that their first days were spent on or near shore.
Everhart, M.J. 2002. Remains of immature mosasaurs (Squamata:
Mosasauridae) from the Niobrara formation (Late Cretaceous) argue against
nearshore nurseries. Sixty-Second Annual Meeting of the Society of
Vertebrate Paleontology. Oct. 9-12. Norman, Okla.