Slow-cooking dinosaur eggs may have contributed to extinction, say scientists

January 4, 2017

A joint research team from the, , and announced on Monday that the eggs of non- dinosaurs such as the  took as long as six months to hatch, far longer than had previously been believed.

Bird eggs incubate for 11 to 85 days, about half the time of most other egg-laying vertebrates. Scientists had thought dinosaur eggs were more like those of modern birds than modern reptiles, but this long hatch time is far more reminiscent of than magpie.

The scientists reached this conclusion by comparing CT scans of the teeth of dinosaur embryos of two different species, the ', which had eggs weighing under 200 s, and ', a type of duck-billed dinosaur that had eggs twenty times that size. They observed the, patterns that form in teeth as they grow, to determine how long the overall developmental process was taking. "They're kind of like tree rings, but they're put down daily," said Florida State University co-author Gregory Erickson. "And so we could literally count them to see how long each dinosaur had been developing." They found the Protoceratops embryo was about three months old and the Hypacrosaurus about six months. According to the research team, this may be one reason why dinosaurs did not recover after the event 65 million years ago. Both the eggs and any parents guarding them would have drawn the attention of predators and been unable to flee floods or other problems. Guardians might not have been able to move far to find food. This, researchers say, would have put dinosaurs at a disadvantage over animals with quicker-hatching eggs and their mammalian competitors.

Natural History Museum Curator and study co-author Mark Norell cites advances in as the reason why this study is being published today: "We know very little about dinosaur embryology, yet it relates to so many aspects of development, life history, and evolution, [b]ut with the help of advanced tools like  and high-resolution, we're making discoveries that we couldn't have imagined 20 years ago." The research team plans to study more fossilized dinosaur embryo skeletons to confirm their findings. Specifically, the current study did not include the skeleton of a or any other dinosaur considered closely related to birds.