The scientists reached this conclusion by comparing CT scans of the teeth of dinosaur embryos of two different species, the , which has eggs weighing under 200 s, and , a type of duck-billed dinosaur that has 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. Skull from a Protoceratops andrewsi embryo. 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.
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. Skull from a Protoceratops andrewsi embryo. 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.
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