Slow incubation of dinosaur eggs

Researchers report the discovery of daily-forming growth lines in the teeth of embryonic nonavian dinosaurs, and counts of the lines suggest that dinosaur egg incubation lasted for months, a period comparable to that for reptiles but slower than typical for birds; prolonged incubation times would have exposed and endangered dinosaurs and their eggs and may have limited dinosaurs’ ability to compete with rapidly generating species after the K-Pg mass extinction event, marked by the disappearance of nonavian dinosaurs. - Read at PNAS.org

Article #16-13716: “Dinosaur incubation periods directly determined from growth-line counts in embryonic teeth show reptilian-grade development,” by Gregory M. Erickson, Darla K. Zelenitsky, David Ian Kay, and Mark A. Norell.