Rewriting the Book on Dinosaurs

Forget what you knew: they weren't necessarily cold-blooded or pea-brained, and may not really be extinct

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A 7-ft.-tall juvenile T. rex, he speculates, was probably very active, capable of scampering like a groundbird. By contrast, mid-size individuals, averaging 12 ft. to 15 ft. in height, were probably somewhat less agile and may have traveled in packs. A full-grown, 40-ft.-long, eight-ton tyrannosaur must have slowed down even more, and may even have reverted to a solitary life-style. Says Brett-Surman: "They certainly wouldn't have turned somersaults across the landscape." As for the giant herbivores, which would have required hundreds of pounds of vegetation a day to sustain their enormous bulk, they might have had their own unique metabolism fueled by the heat given off by nonstop digestion.


In 1978, when Jack Horner happened upon 14 rocky nests in an eastern Montana excavation that was later dubbed Egg Mountain, another dinosaur myth bit the dust. The egg-filled nests belonged to hadrosaurs -- duck-billed dinosaurs -- which had apparently built vast rookeries much the way social birds like penguins do. Though dinosaurs were never thought to be especially cuddly or caring, these creatures clearly nurtured their young, probably feeding them by mouth like baby birds until they were strong enough to leave the nest. Horner and his colleagues named the species Maiasaura -- Greek for "Good Mother Lizard."

The evidence for communal living was the fact that groups of nests were found in a single layer of sediment, implying that they were all built in the same year. Beyond that, the nests were spaced an average of 23 ft. apart -- about the size of an adult maiasaur. Birds often do the same thing, laying their eggs close enough together for maximum mutual protection, yet far enough apart so that they can move easily past their neighbors. Inside the nests, Horner found lots of tiny eggshell fragments. If the baby maiasaurs had simply hatched and wandered off to fend for themselves, he reasoned, the shells would simply be broken; the fact that they were thoroughly smashed convinced him that the babies stayed around to be cared for and fed. He also believes -- somewhat controversially -- that the babies' oversize eyes and snub noses would have appeared "cute" to their parents, the way the same characteristics do in humans, and thus inspired caring behavior.

Whatever the reason, says Horner, "we have pretty good evidence that all duck-billed dinosaurs were nest-bound and nurturing. We also see a lot of herding behavior among hadrosaurs as well as ceratopsians," a group that includes Triceratops. In fact, claims Horner, "most of the herbivores cared for their young."

$ China's leading paleontologist, Dong Zhiming, believes some meat eaters too may have been caring parents. In fact, he takes the contrarian view that Oviraptor, a toothless predator whose very name means egg stealer, is the victim of a bum rap. The sharp-clawed creature has been found in close proximity to nests not because it was poised to devour unhatched babies but because "it was the mother and was protecting them," says Dong.


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