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Therizinosauroid embryos described
From: Ben Creisler firstname.lastname@example.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.