From the instant he saw the egg in the rocks of the Gobi Desert in the summer of 1993, Mark Norell knew he had stumbled upon a time capsule. Peering through the worn-away top of what had been a six-inch egg, he saw the fragile fossilized bones of an 80 million-year-old unhatched dinosaur. Its ankle bones identified it as a theropod, an upright hunter like a velociraptor; the skull, tucked near the knees in a fetal position, was that of an oviraptor, a long-necked predator sort of like an emu with a tail. The embryo is the first to be positively identified as that of a meat-eating dinosaur, the American and Mongolian discoverers announced in the journal Science last week. And for a tiny guy, it's full of promise. An embryo, says Norell, of the American Museum of Natural History, ""allows us to examine . . . questions that scientists are not usually able to,'' such as how dinosaur parents tended their nests and hatchlings, and how the babies looked and behaved.
Past discoveries of embryos have indeed shined a light on the lifestyles of the thundering and famous. Jack Horner of the Museum of the Rockies, the model for Dr. Alan Grant in ""Jurassic Park,'' has found more than two dozen at ""Egg Mountain'' in Montana. Embryos of four-legged maiasaurs, agile little hypsilophodonts and what may be a brainy, carnivorous Troodon all had the big eyes and small chins of a Cretaceous ET. Faces that only a mother could love, suggested Horner, kept the parents from abandoning the hatchlings. The babies may have had other ideas, though: the hypsilophodonts' bones showed the kind of surfaces that would have allowed them to hit the ground running. In contrast, the maiasaur bones were so unformed that the hatchlings would have required extensive care, a suggestion at odds with the old view that dinosaur mothers laid 'em and left 'em.
The cliche that a scientific find is going to ""rewrite the textbooks'' is almost always hype, but the Gobi embryos will demand some redrawing of children's dinosaur books. Many show little Protoceratops, four-legged plant-eaters, lumbering out of their shells. That was based on the 1923 discovery by the swashbuckling dinosaur hunter Roy Chapman Andrews of eggs in the Gobi, where Protoceratops was very common. But those eggs are identical to the ones just discovered: the books should show little oviraptors, not Protoceratops. The misidentification also means that oviraptor got a bum rap. When Andrews found the fossil of an adult oviraptor atop the ""Protoceratops'' eggs, he assumed it was having breakfast; the new find suggests the oviraptors, whatever their diet, were attentive mothers. Harder to explain is another Gobi find. In the same nest were tiny skulls of predators belonging to a group that includes velociraptors. Assuming the oviraptor mother hadn't brought the hunters over for her hatchlings' first playdate, they could have been food. Or, the eggs could have been slipped into the nests by a mother belonging to a different species that didn't want to raise her own brood, much as cuckoos do today. Or, they could have been prowlers. Norell can only guess. Dead bones tell no lies.