Dinos remained in the egg for up to 6 months
PALAEONTOLOGY Depending on the species, dinosaur eggs took 3-6 months to hatch, according to new research by Florida State University. One fossil is from a protoceratops, a dinosaur the size of a sheep, that laid 200g eggs. The other is from a hypacrosaurus, a huge, beaked dinosaur that laid 4 kg eggs the size of volleyballs.
The scientists focused on the newly-developed teeth of the embryos, which include tiny lines indicating daily embryo growth. The lines can be compared to the growth rings of trees, and scientists were able to conclude that the protoceratops egg took three months to hatch, whereas the hypacrosaurus egg took six months. The long time span inside the eggs surprised the scientists, because the period is very vulnerable for both the egg and the broody mother.