Therizinosauroid embryos described

[bh480@scn.org]

From: Ben Creisler bh480@scn.org

In case this item has not been mentioned yet, the new 
issue of Science 305: 1396 (Sept. 3, 2004) has a brief 
description of therizinosauroid embryos from the 7th 
International Congress on Vertebrate Morphology in Boca 
Raton, Florida. Here's a synopsis:

Newly Hatched Dinosaur Babies Hit the Ground Running 
A.Cruickshank of the University of Leicester, U.K., Martin 
Kundrát of Charles University in Prague, Czech Republic, 
and their colleagues studied bones and teeth packed into a 
dozen fossil eggs of therizinosauroids found in Henan 
Province, in east-central China. All the dinosaur embryos 
were at least two-thirds of the way through their 
development. "They had well-ossified limb bones, so they 
can walk immediately after hatching," says Kundrát. 
Fossilized teeth in youngest embryos resemble the teeth of 
the other theropods, well suited for eating meat. In the 
more mature embryos, although the teeth retained some meat-
eating potential, they were more like those seen in adult 
therizinosauroids, which are presumed to be 
herbivores. "We could see the transition of the tooth 
crown and cusp," Kundrát said. 
These data suggest that the hatchlings came out of the egg 
able to chase down prey and consume suitable plants. 
Kundrát suggests that these stages of tooth development 
reflect the evolutionary steps that allowed 
therizinosauroids to arise from carnivorous ancestors.