Light shed on why dinosaurs died out

THE mystery of why the dinosaurs became extinct after the Cretaceous meteor strike, while birds and mammals flourished, may finally have been solved.

Palaeontologists have discovered that dinosaur young took so long to hatch and grow that populations failed to recover quickly enough after the devastating impact 65 million years ago.

In contrast, birds and small mammals only took a few weeks for their offspring to emerge, giving them a distinct advantage.

The discovery was made by scientists at Florida State University and the University of Calgary, who realised it was possible to calculate how long it took for dinosaurs to hatch based on marks on the teeth of embryos and babies.

Just like tree rings growing a new layer each year, teeth grow a new layer each day, which can be seen in microscopic lines in the dentine. By simply counting the lines, scientists found that it took dinosaurs between three and six months to hatch.

The lengthy incubation period made the hatchlings, and their parents, vulnerable and left them struggling to re-establish their species.

“Some of the greatest riddles about dinosaurs pertain to their embryology, virtually nothing is known,” Gregory Erickson, a professor of biological science at Florida, said.

“Our findings have implications for understanding why dinosaurs went extinct, whereas amphibians, birds, mammals and other reptiles made it through and prospered.” – The Telegraph