Aerosteon

Aerosteon was a genus of large theropod dinosaur from the Late Cretaceous period (approximately 84 million years ago) of what is now Argentina. The name Aerosteon riocoloradense translates to "air bone from Río Colorado," referring to the pneumatic, or air-filled, bones that characterized its skeleton and the location of its discovery.

Discovery and Naming

The holotype specimen was discovered in 1996 in the Anacleto Formation of the Río Colorado Subgroup, Neuquén Province, Argentina. It was formally described and named by Sereno, Novas, Forster, Isasi, and Bittar in 2008.

Description

Aerosteon is estimated to have been around 9 to 10 meters (30 to 33 feet) in length. What distinguishes Aerosteon is the presence of extensive pneumaticity in its bones, particularly the vertebrae, ribs, and ilium. Pneumaticity refers to the presence of air sacs that invade the bones, making them lighter without sacrificing strength. These air sacs were connected to the respiratory system, similar to modern birds. It is believed that this adaptation may have played a role in improved respiratory efficiency or weight reduction.

Classification

Phylogenetic analyses have placed Aerosteon within the Megaraptora, a group of large-bodied theropods that are characterized by their enlarged hand claws and pneumatic skeletal features. However, the exact relationships within Megaraptora are still debated, and some researchers propose alternative classifications. The position of Megaraptora itself within Theropoda is also a matter of ongoing research, with some studies suggesting they are allosauroids and others supporting a tyrannosauroid affinity.

Paleoecology

Aerosteon lived during the Late Cretaceous period in what is now Argentina. Its environment would have consisted of diverse dinosaur fauna, including sauropods, ornithopods, and other theropods. It likely occupied a position as an apex predator in its ecosystem.