Fossils of sauropodomorph embryos in a bone bed in Lufeng County contained individual embryos in different stages of development, providing researchers an unprecedented chance to analyze the embryonic development of a prehistoric species, the journal Nature reported Wednesday.
Robert Reisz from the University of Toronto and his colleagues discovered eggshells and more than 200 dis-articulated bones dating to the Early Jurassic period, 197 million to 190 million years ago.
They represent the earliest knows examples of dinosaurs in the embryo state, the researchers said.
"Most of our record of dinosaur embryos is concentrated in the Late Cretaceous period," David Evans, curator of vertebrate paleontology at the Royal Ontario Museum in Toronto said. "This [study] takes a detailed record of dinosaur embryology and pushes it back over 100 million years."
The embryos also provided clues to how adult sauropodomorphs were able to grow to be 30 feet long, larger than any other terrestrial animal alive during the period.
The fossil embryos showed evidence of rapid, sustained embryonic growth and short incubation times, researchers said, and the dinosaurs probably maintained this extreme rate of growth after hatching in an effort to evade predation by outgrowing their predators.
"This may be a model to explain gigantism in this group," Reisz said.