Newfound Dinosaur a Transitional Creature

[Allan Edels <edels@msn.com>]

> From the AP, via Yahoo:

http://story.news.yahoo.com/news?tmpl=story&cid=1894&e=1&u=/ap/20050504/ap_on_sc/dinosaur_diet

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Newfound Dinosaur a Transitional Creature
By MALCOLM RITTER, AP Science Writer
6 minutes ago


Scientists have caught a dinosaur in the act of evolving from meat-eater to 
vegetarian.

The two-legged, feathered creature ate plants, but its bones show that the 
transition from its carnivorous ancestors was still in progress.

All plant-eating dinosaurs were ultimately descended from a meat-eater, and 
switchovers to plant-eating occurred several times. The newly discovered 
species, which lived 125 million years ago in what is now Utah, could help 
scientists understand details of how the changeovers took place.

It's "our first really good case of a dinosaur in the midst of shifting from 
the meat-eating body to a plant-eating one," said an expert not involved in 
the discovery, Thomas R. Holtz Jr. of the University of Maryland.

"It's definitely eating a substantial amount of plants, (but) we still see 
the original imprint of meat-eating upon it."

The creature, with 5-inch claws on its outsized hands, measured some 12 feet 
from its snout to the tip of its long skinny tail. It stood just over 3 feet 
tall at the hip and could apparently reach about five feet off the ground 
with its long neck to munch leaves or fruit, said Utah state paleontologist 
James Kirkland.

He describes the creature in Thursday's issue of the British journal Nature 
with Lindsay Zanno and Scott Sampson of the Utah Museum of Natural History 
at the University of Utah, among others.

They dubbed it Falcarius utahensis. Bones from hundreds or maybe thousands 
of these dinosaurs were discovered at a two-acre dig site in east-central 
Utah, south of the town of Green River. Nobody knows why they gathered there 
or what killed them, Kirkland said.

But analysis revealed that Falcarius was the earliest known member of a 
bizarre-looking group of plant-eaters called therizinosaurs (pronounced 
THAY-rih-ZY-no-sores.) Found mostly in Asia, the barrel-bodied creatures 
waddled upright like Godzilla or "a pot-bellied bear," Kirkland said.

Falcarius, very early in its evolution into the therizinosaur body type, 
retained the rather horizontal posture and built-for-speed legs of its 
meat-eating ancestors. But it had already lost the flattened and serrated 
teeth used to tear meat and acquired the smaller, more densely packed teeth 
of a vegetarian, Zanno said.

It also showed some change toward the larger gut needed to digest plant 
material rather than meat, as well as a lengthened neck and smaller head 
associated with eating plants, she said.

Holtz said Falcarius still had fairly slender proportions overall rather 
than the barrel body of later therizinosaurs. "This one could probably move 
fairly quickly," he said, whereas its more evolved relatives "would have had 
problems hunting things faster than a tree."

Kirkland and Zanno said they suspect Falcarius probably ate some meat in 
addition to plants.

"I wouldn't doubt this thing would eat a lizard or two in a pinch," Kirkland 
said.

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Congrats to Jim and Lindsay (and to Tom for being a prime source [as an 
uninvolved scientist] for the article :-)

Allan Edels