Scientists from Florida State University studied dinosaur embryo fossils and used the data to estimate how long it took typical dinosaur eggs to hatch. The team found that the dinosaur eggs took an average of three to six months to hatch. The details are in a paper that was just published in the journal Proceedings of the National Academy of Sciences.
Little is known about dinosaur eggs and their developing embryos. Fossilized embryos are very rare and are usually far along in development, leaving early embryonic development as a bit of a mystery. Scientists have long wondered whether dinosaur eggs take a long time to develop and hatch. Crocodilian eggs can take months to hatch, for example. On the other hand, dinosaurs are closely related to modern birds and bird eggs take a month or less. Canary eggs take less than two weeks to hatch—a huge difference when compared to crocodilians that incubate their eggs for months.
A team of researchers acquired fossils of early dinosaur embryos. The team specifically studied fossils of Protoceratops and Hypacrosaurus. Protoceratops were sheep-sized herbivores with large neck frills. Dinosaurs in the Hypacrosaurus genus had duckbills, rounded crests, and spines along their backs. The researchers analyzed the fossilized embryonic jaws with a CT scanner and studied extracted teeth with high-powered microscopes. They looked for growth lines on the teeth—bands found in tooth enamel that correlate to how long the teeth have been growing. By analyzed these bands, the team could figure out far along the dinosaur embryos were in the developmental process. Using this information, the team dated the Protoceratops embryo at three months and the Hypacrosaurus embryo at six months old. This means that dinosaur eggs in these and related species took a minimum of three months to hatch and over six months in some cases. Dinosaur eggs had long developmental stages, just like crocodilians.
The research team was able to date fossilized dinosaur embryos and determined that dinosaur eggs took at least three to six months to hatch. These findings are interesting because they suggest that dinosaur eggs took much longer to hatch than bird eggs—surprising results since birds are modern day dinosaurs. The team believes that this long development time could have contributed to the extinction of certain dinosaur species.
Shubin et al. Dinosaur incubation periods directly determined from growth-line counts in embryonic teeth show reptilian-grade development. Proceedings of the National Academy of Sciences (2017).