Aerosteon

What it was like

Aerosteon was a large meat eater from the megaraptoran group, relatives of Megaraptor and Australovenator. Its bones are full of hollow spaces that held air sacs, much like the bones of living birds.

Those air-filled bones are the reason for its name. They suggest it breathed with a bird-like system of air sacs, which may have helped it take in oxygen and kept its skeleton light.

Its world

Aerosteon lived about 84 to 72 million years ago, in the Late Cretaceous, in what is now Argentina. Its bones come from the Anacleto Formation, home to the abelisaurid Aucasaurus, the small plant eater Gasparinisaura and titanosaurs such as Neuquensaurus and Antarctosaurus.

How it was found

Sereno and colleagues named Aerosteon in 2008 from a single partial skeleton. Scientists are still working out exactly where megaraptorans sit on the theropod family tree.