For decades now, the drumbeat of dinosaur news has been their similarity to birds. They were warmblooded! They had feathers! And they’re still around, because birds are actually dinosaurs.
All true, but those that were nonavian dinosaurs, as they are now called, were not all beak and tweet. They were closely related to other living reptiles like crocodiles, and new findings about how long their eggs took to hatch bring that point home. According to paleontologists’ discoveries dinosaur young took so long to hatch and grow into adulthood that populations failed to recover quickly enough after the devastating impact 65 million years ago.
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.
That long incubation process might have contributed towards the dinosaurs dying out. Besides taking too long time to hatch, it would also take them long enough to become mature. So if to count all together it took dinosaurs around two years to become fully grown and mature from being conceived – far too long in the harsh environment after the comet or asteroid hit.
The traditional explanation of a rock crashing into Earth and wiping them out still holds – but the new research suggests that the eggs taking so long might have slowed down the repopulation after that fact, holding the dinosaurs back from replacing those animals that were wiped out during the catastrophic event.
Scientists say that the same findings could help inform our understanding of what the dinosaurs were doing when they were alive, however. They probably migrated less than we had previously thought given how hard it would be to do that while having young, for instance.