Oviraptor Ruminations

Dinosaur Found Crouching Over Eggs Like Bird

LONDON, Dec 20 (Reuter) - A fossilized dinosaur found incubating its eggs has offered the most graphic evidence yet of how they may have been the precursor of the modern bird.

The spectacular specimen, found buried under sand in Mongolia, is crouched on a nest of at least 15 eggs.

Its hindlimbs are folded on each side of the nest like the brooding posture of the modern bird, Mark Norell of the American Museum of Natural History reported in Nature Magazine on Wednesday.

"This finding provides the strongest evidence yet that modern avian brooding behavior evolved long before the origin of modern birds," Morell and his colleagues concluded after studying the superbly preserved Oviraptor.

The fossil, found at Ukhaa Tolgod in Mongolia, contains the dinosaur's ribs and most of the limbs.

From: Dinogeorge@aol.com

In a message dated 95-12-28 22:39:59 EST, BGNewhouse@aol.com writes:

>Greetings--
>Forgive this minor suggestion from a dinosaur groupie:
>but I was speaking to my mother (no paleontologist, but she never met a
>feathered coelurosaur she didn't like) Christmas Eve, and she suggested that
>perhaps the Oviraptor found on a nest of eggs was caught at the moment of
>actually laying them rather than simply brooding them, like the Velociraptor
>and the Protoceratops fossilized while fighting--just a thought--

The authors of the paper address this very point and conclude that the animal was probably not laying the eggs, because no eggs or shells were found within the body cavity.

From: Rich Travsky [rtravsky@UWYO.EDU]

Unless, by fantastic coincidence, it had just finished laying them.

I haven't seen the article. What was the critter's gender? If it was male, that'd sure settle the question.

From: GSP1954@aol.com

The new Oviraptor on the nest has its arms drapped around the eggs in a classic brooding posture, and the egg ring was complete. Egg laying was probably already finished (and could have included eggs from various females, as per some ratites).

It has been suggested that the Oviraptor was shading the eggs rather than keeping them warm. It is possible that this was true at that moment of death, but exposed eggs will suffer from the cool night unless kept warm.

Since the oviraptors were nesting in a desert where night temperatures were probably low even in the summer, this would be an important concern. All brooded eggs are therefore warmed as well as shaded. It is therefore probable that the brooding theropod was generating high levels of heat at least at night. Pythons brood eggs, but their method of using muscular contractions of a long sinuous body appears ill suited for a theropod. It is more likely that the oviraptor was producing heat in a more avian manner.

It is interesting that the body and arms did not entirely cover the eggs. This hints that insulation was present to cover the eggs for both heat retention, and shading, as in birds. It is frustrating that two new European theropods appear to have integument preserved, but neither has been described in detail.

In response to a question on whether the new oviraptor find is really an "old" find, perhaps from the Roy Chapman Andrews expedition of the early 20th century, and whether all the eggs found by Andrews and others really belong to oviraptors rather than protoceratopians as previously thought, Mark Norell of the American Museum of Natural History wrote:

1) At Djadoktha (Bayn Dzaka and Bayan Mandahu) and Djadoktha like (Kheerman Tsav, Khulson, Ukhaa Tolgod) localities several different kinds of eggs are found. The only ones that can be definitively identified are those that contain oviraptorid embryos and those that contain Gobipteryx embryos. Some eggs may in fact be Protoceratops, but we have no idea of knowing which ones those are. The most common eggs and the best preserved nests collected by American Museum expeditions (in the 20's and now) and Polish, Russian and Mongolian expeditions are oviraptorids.

2) the new reconstructions of oviraptorids coming out of people associated with our group is based on new material collected during the Mongolian-AMNH expeditions. This material is also identical to specimens collected by Mongolian expeditions housed in Ulaan Baatar. At this time we feel that the material is probably referable to philoceratops.