Timothy Huang, a chemist at National Chung Hsing University in Taiwan and an amateur archaeologist, discovered the embryonic bones about three years ago in Yunnan Province, China. The bone bed has an area of about 3 square feet (1 square meter) and a thickness of about 4 to 8 inches (10 to 20 centimeters). In this small patch, the researchers eventually uncovered more than 200 itsy-bitsy bones.
A geological analysis of the spot revealed that slow flooding probably smothered the eggs, which seem to have been laid in a colonial nesting site. After the flood, the embryos and eggs rotted and fell apart, leaving a mound of disarticulated bones. The bones date to the Lower Jurassic period, or between 199.6 million and 175.6 million years ago. That makes them just as ancient as the oldest known embryos ever found, which were discovered at a nesting site of long-necked Massospondylus dinosaurs in South Africa.
It was a boon for science that the dino embryos had fallen apart, instead of fossilizing inside their eggs, Reisz told LiveScience.
"People are extremely possessive and fond of their embryos inside their eggs — imagine us asking them to take pieces out and do the sections on them and cut them, and essentially do damage to them," he said. "These bones are completely disarticulated, and we have a lot of them — so it's not unreasonable to be able to take a few and cut them, and see what their internal anatomy is like."