Friday, October 15, 2010

Sarahsaurus aurifontanalis, A New Sauropodomorph

Dispersal and diversity in the earliest North American sauropodomorph dinosaurs, with a description of a new taxon. T. Rowe, et al. Proc. R. Soc. B published online before print October 6, 2010

A new sauropodomorph from Arizona, Sarahsaurus aurifontanalis, lived about 190 million years ago (Early Jurassic Period) and was 14 feet long and weighed about 250 pounds.

Evidence from Sarahsaurus and two other early sauropodomorphs suggests that each migrated into North America at the end of the Triassic Period 200 million years ago in separate waves long after the Triassic extinction, and that no such dinosaurs migrated there before the extinction.

Sarahsaurus had physical traits usually associated with gigantic animals. For example, its thigh bones were long and straight like pillars, yet were not much larger than a human's thigh bones. Sarahsaurus shows that sauropodmorphs started out small and later evolved to a very large size.

Click to Enlarge
"We've never found anything like this in western North America," he said. "Its hand is smaller than my hand, but if you line the base of the thumbs up, this small hand is much more powerfully built than my hand and it has these big claws. It's a very strange animal. It's doing something with its hands that involved great strength and power, but we don't know what."

Sarahsaurus is named in honor of Sarah (Mrs. Ernest) Butler, an Austin philanthropist and long time supporter of the arts and sciences. Butler chaired a fundraising committee for the Dino Pit, an interactive exhibit Rowe helped create at the Austin Nature and Science Center that encourages children to dig up their own fossil replicas.

"I told her if she really raised a million dollars to build the Dino Pit, I'd name a dinosaur after her," he said. link