Dinosaur embryos wiggled around in their eggs just like the embryos of modern birds, scientists have found. The boffins made the discovery after a cache of fossilised dino bones and eggs were dug up in southwest China.
The scientists are hoping to find out more about the Jurassic-era creatures by analysing remnants of complex proteins found in some of the 190-million-year-old fossils.
The researchers studying the oldest dino-embryo fossils ever found have hypothesised that they moved within the egg to exercise muscles and encourage their bones to grow.
More than 200 fossilised bones were dug out of a site near Lufeng in Yunnan, south west China. All the specimens come from the genus called Lufengosaurus, a long-necked, herbivorous beast which weighed more than a tonne and grew up to nine metres long.
Normally scientists find eggs within nests, meaning that they are all at similar points of development. But the huge Lufeng sample featured dinos which were in several different growth stages.
Robert Reisz, a palaeontologist from the University of Toronto Mississauga, in Canada, said: "We are looking at various stages in the embryonic life of this animal, and we can put this together to get a growth trajectory of the embryo itself - something that has never been done before."
Researchers analysed the femurs of the specimens and found that the bone appeared to be growing extremely quickly within the egg, which indicates that eggs may have been incubated for just a short period.
They also found that the bones were pulled around by muscles inside the eggs, bending them into shape.
"This suggests that dinosaurs, like modern birds, moved around inside their eggs," said Reisz. "It represents the first evidence of such movement in a dinosaur."
DInosaur embryos are incredibly rare, generally found only in strata traced back to the Upper Cretaceous, and difficult to study, for the obvious reason that they are found within eggs which scientists are often loathe to crack.
So there was great excitement when three years ago, palaeontologists found the remains of 20 Lufengosaurus embryos among a pile of fossilised bones which dated back to the Jurassic period and are 190 to 197 million years old.
Prof Reisz added: "The nests were inundated by water and basically smothered, and the embryos inside the eggs died and then decayed. "And then more water activity moved the bones and concentrated them into a very small area. We only excavated 1m2 of the 'bone bed' and we got more than 200 bones.
He suggested the team’s finding proved that dinosaurs emerged from their eggs in a relatively developed state, ready to face the perils of the Jurassic era.
The research was published in Nature. ®
*DNA's half-life is about 500 years, though fragments of incomplete degrading DNA remain as the proteins slowly dissolve over hundreds of thousands of years. These remains are 190 million years old. Nevertheless, one of the scientists found it necessary to explain, here, that “resurrecting a dinosaur is out of the question."