(American Museum of Natural History) New research on the teeth of fossilized dinosaur embryos indicates that the eggs of non-avian dinosaurs took a long time to hatch –between about three and six months. The study finds that contrary to previous assumptions, dinosaur incubation is more similar to that of typical reptiles than of birds. The work suggests that prolonged incubation may have affected dinosaurs’ ability to compete following the mass extinction event that occurred 65 million years ago.