Soft Dino Shells

A clutch of soft-shelled snake eggs surrounded by dirt

Which came first? The chicken or the soft shelled egg? 

This is Sandra Tsing Loh with the Loh Down on Science.

For ages it was believed that dinosaur eggs were hard shelled – like chicken eggs! But is there a crack in that theory? 

Mark Norell and colleagues from the American Museum of Natural History traveled to the Mongolian Gobi Desert to investigate! There, they found two nests of fossilised embryos and shell fragments from two different dinos. Hard or soft? After seventy five million years, it’s hard to tell!

To find out, Norell shined laser light on the shells under a microscope. The light’s interaction with chemicals in the shell reveals which minerals are there. The team compared the minerals to those in eggs of modern day relatives – birds and turtles! 

Results? Minerals in the dino eggs closely matched soft-shelled turtle eggs. So soft dino shells, it is!

Norell thinks that dinos started with soft shells but eventually developed hard shells. This let them lay eggs on bare ground without the eggs drying out. 

SO much to learn about the past – It’s PETRIFYING!

Reference: Norell, M., et al. (2020). The first dinosaur egg was soft. Nature, 583, 406-410.