A pelvis can say so much
It's an impressive piece of detective work to take a fragment of a fossil and learn something about the behavior of dinosaurs. This is a fossil that consists of only the pelvic region of an oviraptor, which also happens to have a pair of large eggs nestled inside it. This poor female was pregnant at the time of her death, and was just about ready to lay these eggs.
It doesn't sound like much, but here's what we learn from it:
- Oviraptors had two functional oviducts, like modern crocodiles. They laid their eggs in pairs.
- These are large eggs, and the animal didn't have a lot of room in there—so it only laid a few at a time. It wasn't like modern sea turtles, dumping a load of eggs in a nest all at once.
- Oviraptor nests have been found, and they contain many eggs. This had to have been done by repeated visits and multiple egg-laying sessions, suggesting a fair amount of parental investment in the nest.
- The pointed end of the egg is pointed caudally. In oviraptor nests, the eggs are all in circular rings, with the pointed end outward. From this we can infer that the mother oviraptor stood in the center of the nest when laying the eggs.
Isn't it cool where a little evidence and logic will take you?

The oviraptorosaurian specimen at the National Museum of Natural Science in Taiwan (specimen no. NMNS-VPDINO-2002-0901) was excavated from the Upper Cretaceous Nanxiong Formation of the Hongcheng Basin near the city of Ganzhou, in the southern Jiangxi Province, China. It consists of six sacral vertebrae; the first two caudal vertebrae; the ilia, pubes, ischia, and femora; the lower part of the left leg; and a pair of eggs inside the pelvis. The pubes and ischia are slightly disarticulated, but otherwise these bones retain their original anatomical relationships. The eggs are located dorsal to the pubic symphysis, about one egg length anterior to the cloacal region. They are side by side and closely apposed, although the right egg was slightly more ventrally positioned than the left egg. Y.-n.C. and Y.-f.H. supervised the preparation of NMNS-VPDINO-2002-0901, confirming that it is not a composite.
Sato T, Cheng Y-n, Wu X-c, Zelenitsky DK, Hsiao Y-f (2005) A Pair of Shelled Eggs Inside A Female Dinosaur. Science 308(5720):375.


When I was a child, I wanted to be a paleontologist (studying dinosaurs naturally). As a teenager I learned that vertebrate paleontology was a dead dead dead field. I gave it up for the stars. I don't exactly regret my decision, but on days like this I do feel a twinge......
Might cool stuff.