How cute were baby dinosaurs

Paleontology: Dino babies did not hatch for three to six months

Millions of years ago, baby dinosaurs probably took longer to hatch than researchers previously assumed: some of them spent around three to six months in the egg at the beginning of their life, according to a team led by Mark Norell from the American Museum of Natural History.

With the help of computed tomography and microscopy, Norell and his colleagues examined the dentition of well-preserved dinosaur embryos that came from two very different species: while some of the fossils belong to the genus Protoceratops belonged, whose representatives were not even three feet tall and laid quite small, light eggs, the other skeletons came from giant dinosaurs of the genus Hypacrosauruswhose eggs alone weighed four kilograms. Based on the typical line patterns that, similar to the annual rings of trees, form in the dentin over time, the scientists were finally able to determine that the Protoceratops-Embyrones were about three months old at the time of their death, while the Hypacrosaurus-Babies developed in the egg for around six months.

This article is contained in Spectrum - The Week 01/2017

So far, researchers had assumed that the breeding season of dinosaurs was more like that of modern birds, whose young hatch after about 11 to 85 days. The dinosaurs were obviously too slow for that - they apparently brooded more like reptiles, whose young grow up in the egg for twice as long. That could perhaps have played a role in the extinction of the dinosaurs, the researchers speculate. Because if the offspring is longer in the egg, the baby, like parents, is more susceptible to falling prey to other predators, to starvation or to death as a result of unfavorable changes in the environment. Norell and his team also say: If you look at the breeding season of dinosaurs, which are more similar to the birds living today than the two species studied, a completely different picture could emerge. So far, however, there are no fossils for this: dinosaur embryos are only very rarely found.