Baby Dinosaurs Needy, Oldest-Known Embryos Suggest

The oldest dinosaur embryos ever discovered indicate that hatchlings were surprisingly helpless and required intense care from their parents, researchers reported Friday in the journal Science.

Although the embryos were close to hatching, they lacked teeth and had underdeveloped bodies. Scientists surmise that the creatures probably walked on four legs after birth -- unlike their parents, which used two.

Found in 1978 under the 183-million-year-old Drakensberg lava flow in South Africa, the Massospondylus carinatus embryos are 30 million years older than previously discovered specimens, said the study’s lead author, paleontologist Robert R. Reisz of the University of Toronto at Mississauga. The dinosaur lived from roughly 227 million to 180 million years ago. The plant eaters grew to about 15 feet from snout to tail.

“You could say we have the ‘Guinness Book of Records’ for oldest dinosaur embryos, and that’s really cool,” Reisz said. “But the science is what excites me: to see how the dinosaur developed, from an embryo to an adult.”

Each of the six whitish eggs, somewhat rounder than chicken eggs, measures about 2 inches long. The eggs had been on display at the University of the Witwatersrand, Johannesburg, their extreme fragility hindering inspection of the contents.

Reisz’s team finally used miniature jackhammers and drills under powerful microscopes to remove the surrounding rock.

The nearly hatched prosauropods had disproportionately enormous heads and long forelimbs compared to adults of the species, which had small heads and short forelimbs.

The newborn body type and four-legged posture may have given rise to similar features among the prosauropods’ evolutionary descendants, the sauropods, such as the massive apatosaurus.