April 14, 2005

The first-ever discovery of two shelled eggs found inside a female dinosaur will help paleontologists further unravel the mysteries of dinosaur reproduction, says a University of Calgary researcher whose work appears in the April 15 issue of Science magazine. The discovery provides further scientific evidence that dinosaurs were evolving to become birds, which further supports the theory that birds are dinosaurs.

“ It’s the first find of its kind,” says Dr. Darla Zelenitsky, a postdoctoral fellow in paleontology at the University of Calgary and the Royal Tyrrell Museum. “Shelled eggs have never been found inside any vertebrate fossil, be it either a dinosaur, turtle, lizard or crocodile.”

The discovery adds further intrigue to the debate among scientists that questions if dinosaurs are more similar to reptiles or birds. “From a reproductive perspective, this particular specimen shows that the dinosaur was in transition between reptiles and birds,” says Zelenitsky, whose postdoctoral fellowship is supported through the Alberta Ingenuity Fund.

This recent discovery adds another piece to the growing clues that birds are indeed dinosaurs; paleontologists from around the world have already found dinosaurs sitting on top of their nests like birds do, sleeping in positions similar to birds with their head tucked in, covered in feathers and the latest, producing one egg at a time like birds.

Zelenitsky is co-author of the Science journal article along with Tamaki Sato and Xiao-chun Wu from the Canadian Museum of Nature, Yen-nien Cheng from the National Museum of Natural Science in Taiwan, and Yu-fu Hsiao from the Paleowonders Fossil and Mineral Museum in Taiwan.

“Canadian paleontologists have been collaborating with researchers of different countries, resulting in spectacular findings in various places. I’ve been fortunate to work in this Canadian multi-national team,” says lead author, Dr. Tamaki Sato, a Japanese postdoctoral fellow at the Canadian Museum of Nature.

The specimen was found in southern China in 2002, and when a Chinese paleontologist discovered that the specimen included the hips, limbs, and part of the tail of an oviraptorid dinosaur as well as two eggs lying side by side between the hips, Zelenitsky was called in. She has been investigating dinosaurs’ reproductive biology for the last 10 years, including fossilized egg nests (clutches) and dinosaur embryos, and is considered an international expert in the area of dinosaur reproductive biology.

The discovery is hailed as a major achievement by leading paleontologists. “A number of people working with dinosaur eggs noticed that the elongate eggs of oviraptorids seemed to have been laid in pairs. However, a number of scientists were skeptical, and the only way to resolve the dispute was to find the eggs lined up inside the body cavity. As unlikely as it seemed that such a specimen would ever be found, we now have the smoking gun!” says Dr. Philip Currie, Curator of Dinosaurs at the Royal Tyrrell Museum and adjunct professor at the Department of Geology and Geophysics at the U of C.

Crocodiles have two functional oviducts, which are part of the reproductive system where eggs are formed, and produce numerous eggs at a time, which are then laid all at once. Birds on the other hand only have one functional oviduct, producing one egg at a time, which is then laid before another egg is formed.

“The dinosaur specimen with two eggs side by side shows that both the left and the right oviducts are still functional but that only two eggs are produced at a time (one from each oviduct) and laid before the next pair is formed,” explains Zelenitsky.

Before Zelenitsky ever heard of the specimen from China, she was trying to find ways to explain the paired egg phenomena in the clutches she was finding in southern Alberta. “This new discovery brings much insight into my research; now I want to investigate if this is also the case in other, more primitive types of dinosaurs,” says Zelenitsky.

Science magazine is an international weekly peered-reviewed journal published by the American Association for the Advancement of Science (AAAS), which is celebrating its 125th year of publishing this year and which has gained an international reputation for publishing top-science discoveries.

To arrange interviews with Dr. Darla Zelenitsky please contact Natalie St-Denis, University of Calgary Media Relations at 403-283-9424, 403-874-9016 (cell) or nstdenis@shaw.ca. Dr. Zelenitsky will be available for interviews today, Thursday, April 14, from 10 am to 12 pm.

__________

Gregory Harris
Media Relations
External Relations
Administration Building, A113
University of Calgary
2500 University Drive N.W.
T2N 1N4
Phone (403) 220-3506
Cell (403) 540-7306
Fax (403) 282-8413