Researchers Estimate Dinosaur Eggs Took 3 to 6 Months to Hatch

Posted on January 2, 2017

Hypacrosaurus embryo fossil

Researchers from Florida State University estimate that it took about 3 to 6 months for a dinosaur egg to hatch. The time would vary for different species of dinosaurs. By comparison bird eggs hatch in periods ranging from 11-85 days. The research was led by FSU Professor of Biological Science Gregory Erickson.

Erickson says in a statement, "Some of the greatest riddles about dinosaurs pertain to their embryology -- virtually nothing is known. Did their eggs incubate slowly like their reptilian cousins -- crocodilians and lizards? Or rapidly like living dinosaurs -- the birds?"

The researchers examined dinosaur embryos from Protoceratops (sheep-sized dinosaur) and Hypacrosaurus (large duck-billed dinosaur) and focused on development of the teeth. They ran the embryonic jaws through a CT scanner to visualize the forming dentition. They also examined some extracted teeth under microscopes. Growth lines on the teeth showed researchers precisely how long the dinosaurs had been growing in the eggs.

Erickson says, "These are the lines that are laid down when any animal's teeth develops. They're kind of like tree rings, but they're put down daily. We could literally count them to see how long each dinosaur had been developing."

The results of the research showed nearly three months for the small Protoceratops embryos and six months for those from the giant Hypacrosaurus. A fossilized Hypacrosaurus embryo is pictured above. The research paper was published in Proceedings of the National Academy of Sciences.

Photo: Courtesy of Darla Zelinitsky