A Calgary-found dinosaur embryo is giving scientists a new perspective on how long it took dinosaur eggs to hatch. Previously, scientists thought that the dinosaur egg incubation period would be similar to that of birds, somewhere between 11 to 85 days. The larger the egg (at least in the case of birds), the longer the incubation period. However, the incubation period was apparently more like that of lizards.
Gregory Erickson of Florida State University lead a team of researchers in a study that was published in Proceedings of the National Academy of Sciences. Erickson examined a Hypacrosaurus, found in Calgary, and a Protoceratops found by the American Museum of Natural History in the Mongolian Gobi Desert for the study. Dinosaur embryos are not readily available to study since there are less than 10 known dinosaur embryos in existence.
Erickson was able to examine embryos on both ends of the dinosaur size spectrum. The Hypacrosaurus are some of the largest known dinosaurs, with eggs that weigh four kilograms and resemble volleyballs. On the other hand, Protoceratops eggs are some of the smallest dinosaur eggs that researchers have found.
The key was to study the growth lines on the dinosaurs’ teeth. Like other animals such as crocodiles, the teeth form a new line each day that they develop. Erickson found that the small Protoceratops had an incubation period of three months and the large Hypacrosaurus had an incubation period of about six months.