I love the late Cretaceous! It used to be a big mystery when I was a kid, and there was actually a lot of disagreement between scientists about the evolution of raptors and birds. Evidence has been rolling in for the last 30 years, and there are just so many cool pre-birds (that’s what I call them, most scientists would probably have a better name).
This is Citipati. They were huge (emu sized). At least four Citipati specimens have been found in brooding positions, the most famous is a large specimen nicknamed “Big Mamma” found in the Gobi Desert. All of the nesting specimens are situated on top of egg clutches, with their limbs spread symmetrically on each side of the nest, possibly-feathered front limbs covering the nest perimeter. This brooding posture is found today only in birds and supports a behavioral link between birds and theropod dinosaurs.
They are in the genus oviraptorid, or egg-theives, but they were totally misnamed at first. Oviraptor was originally presumed to have eaten eggs, based on its association with a fossilized nest thought to belong to Protoceratops. The discovery of actual nesting specimens of Citipati with the same types of egg showed that they were likely brooding the eggs, not feeding on them.
1. Citipati brooding behavior
2. Big Momma
3. Big Auntie
4. close up
5. A 1922 illustration incorrectly showing reptilian-like protoceratops guarding “their” eggs from the Citipati.