Avisaurus

Extinct genus of birds

Avisaurus (meaning "bird lizard") is a genus of enantiornithine bird from the Late Cretaceous of North America.

The specimen has a maximum length of , making it one of the largest known tarsometatarsi of an enantiornithine. RAM 14306, an incomplete coracoid, is bigger than the holotype. It indicates an animal with a length of , hip height of , and weight of .

This genus belongs to the enantiornithine family Avisauridae, which also contains similar animals from South America such as Soroavisaurus and Neuquenornis In the Late Cretaceous the Americas were still separated by a branch of the Tethys Ocean. The paper by Brett Surman and Paul in 1985 explicitly considered the possibility that A. archibaldi was an enantiornithine. The authors described and named UCMP 117600 formally, but they looked at other enantiornithine material, including the "metatarsus" PVL 4690 from Argentina. The authors assigned this latter fossil to Avisaurus sp. From this they concluded that members of the genus Avisaurus existed in both North and South America in the Late Cretaceous. Moreover, the authors concluded that the length/width ratio and degree of metacarpal fusion of these bones were more like those of non — avian dinosaurs. A terrestrial dinosaur genus in both continents would then support Brett — Surman's theory that there had been a land connection between the two continents. Further discoveries and further study by Chiappe showed that all of the material belonged to enantiornithine birds, and PVL 4690 was given its own genus Soroavisaurus.