Dinosaur Embryo Fossils Date Back 190 Million Years, Reveal How Creature Grew

Scientists working in southwestern China have uncovered a group of 190 million-year-old dinosaur embryos that, for the first time, prove a long-held theory that the Lufengosaurus, a long-necked dinosaur whose adults measured 30 feet long, grew much quicker inside the egg than other dinosaurs. What's more, the creature further appeared to have flexed its muscles in a way similar to humans.

Published in Thursday's issue of the journal Nature, University of Toronto paleontologist Robert Reisz said the fossils are the same age as another set he and his team discovered in South Africa eight years ago. At that point, they were the oldest dinosaur embryos ever found.

In fact, the two types of dinosaurs, which both date back to the Jurassic period, are close relatives.

The discovery of the embryos in China isn't necessarily new - Reisz and his team first found them three years ago. However, as is often the case, it took the team several years to finish analyzing the find, which included examining more than 200 bones from 20 individual animals.

The current find proved to be especially advantageous to those working on the project because, unlike the previous discovery in which the dinosaur embryos were still neatly tucked inside their fossilized eggs, these fossils contained scattered bones, letting researchers examine them in greater detail.

What's more, through spectroscopic analysis of bone-tissue samples form the site, researchers determined that they had discovered the oldest organic material in a terrestrial vertebrate. Such a find was astonishing to the paleontologists given the porous and delicate nature of the fossilized femur bones, which ought to have been vulnerable to corrosive effects of weathering and groundwater.

As Reisz told the journal, "That suggests to us that other dinosaur fossils might have organic remains. We just haven't looked at them in the right ways."