Einstein Science Reporting for Kids
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14-Apr-2005

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Dinosaur eggs discovered inside mother



Image of the left egg found inside the female dinosaur. The blue color of the egg shell fragments is not the original color. The texture of the shell pieces is probably similar to the original texture of the egg.
Click here for a high resolution photo.

Scientists have discovered a dinosaur that died right before it laid two eggs.

Finding dinosaur eggs inside the female, in almost the same position they were in when she died, might answer some tough questions about dinosaur egg-laying.

In the 15 April 2005 issue of the journal Science, the scientists who first studied the dinosaur from China explain what the eggs looked like and exactly where the eggs were inside their mother.




Click here for a high resolution photo.

To imagine what the two eggs looked like, picture a pineapple-sized potato. As for the color of the eggs, you'll have to use your imagination. In the picture, the egg shell pieces look blue and brown, but the scientists are not sure of the original color.

Finding dinosaur eggs within the mom is so cool because it gives scientists the "inside story" of dinosaur egg laying.

Science author Tamaki Sato from the Canadian Museum of Nature in Ottawa, Canada explained that there are lots of things we don't know about dinosaur egg laying.

For example: Did dinosaurs lay all their eggs at once, like crocodiles? Or did dinosaurs lay one egg at a time, like birds?




Click here for a high resolution photograph.

Based on her careful study of the female's bones and the eggs, Sato explained this dinosaur laid eggs like a crocodile some ways and like a bird in other ways.




Click here for a high resolution photograph.

Like a crocodile, the dinosaur had two "egg-makers" or ovaries. Each ovary was connected to a tube. Inside this tube, the egg received its hard shell. After getting a hard shell, the egg traveled to the light and the end of the tunnel -- the outside world.

Birds are different. They only have one ovary-tube combo.

Like a bird but unlike a crocodile, the dinosaur could not lay all its eggs at once. Finding a dinosaur with only two eggs inside her at one time provides some great clues. It suggests that she made two eggs, laid them, and then repeated the process until her nest was full. Nests of similar dinosaurs have been discovered with more than a dozen eggs inside.

The story doesn't stop here, though. Dinosaur egg laying is a part of a bigger mystery, the mystery of where birds came from.

Birds didn't just fly to Earth from outer space one spring. Many scientists think birds developed from dinosaurs.

The dinosaur the scientists studied is from a group of dinosaurs called "oviraptorosaurians." From head to tail, this dinosaur probably measured three to four meters, or 10 to 13 feet. It is important to know that oviraptorosaurians are from a larger group of dinosaurs called theropods. And theropods are the dinosaurs that are thought to have been the ancestors to modern birds.

Let's review: The scientists found a dinosaur that laid eggs in a way that is like reptiles in some ways and birds in other ways. This fossil alone does not prove anything about the bird-dinosaur connection. But the new discoveries do agree with the scientific idea that birds came from dinosaurs. And in the world of science, discovering new pieces that fit into an unfinished puzzle can bring us closer to seeing a full picture of our natural world.

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