Scientists find eggs in dinosaur mom
Discovery offers clues on prehistoric reptile's reproduction
By Marsha Walton
(CNN) -- A chance to work on a historic dinosaur discovery seems a fitting reward for a paleontologist who first said the word tyrannosaurus at age 3.
In the journal Science, Tamaki Sato describes the discovery of two shelled eggs found inside a dinosaur that died before laying them.
A geologist found the fossilized remains in China's Jiangxi province and sold them to a museum.
"The museum that purchased it did not know there were any eggs inside," said Sato, a paleontologist at the Canadian Museum of Nature in Ottawa. "They thought it was just a skeleton."
But as researchers were preparing the 14-by-14-inch pelvis, they discovered the shelled eggs within the female dinosaur's body cavity.
Sato described the eggs as bumpy in texture, somewhat elongated and looking a bit like "pineapple-sized potatoes."
The dinosaur was an oviraptorosaurian, a subgroup of theropods, and probably stood 10 to 13 feet tall when it lived 65 million to 100 million years ago, Sato said.
Theropods, (which means "fierce footed") were carnivorous, bipedal reptiles believed to be the ancestors of modern birds. The clues provided by the Chinese discovery suggest that the dinosaur had a reproductive system with some similarities to ancient reptiles and some to modern birds.
Like crocodiles and some other modern reptiles, this dinosaur had two ovaries and oviducts. But unlike crocodiles, which lay an average of 50 eggs at a time, the dinosaur had the birdlike characteristic of producing one larger, shelled egg at a time.
Scientists previously have found more than a dozen dinosaur eggs in nests in the same region of China as well as in Mongolia.
Sato said combining knowledge from those discoveries with this latest find could add dramatically to the knowledge of dinosaur reproductive biology.
For example, she said, the shape of the eggs, with a slightly pointed end on each one, indicates that the female went to the center of the nest to lay ring-shaped clutches, or groups of eggs.
"By combining that information, we can have a great idea about how dinosaurs laid eggs," Sato said. "It is rare in paleontology that we can study this kind of behavior. This specimen will be very important."
The specimen, which researchers said is in good condition, is at the National Museum of Natural Sciences in Taiwan. It will be studied further to determine when the dinosaur lived exactly and how she died, right before she would have laid the eggs.