The 80 million-year-old fossil remains of Shuvuuia deserti—derived from the Mongolian word for “bird” and the Latin for “desert”—were found in the Gobi Desert of Mongolia. This was the first skull found from an animal belonging to a family called the Alvarezsauridae, which some scientists believe represents an advanced stage in the transition from dinosaurs to birds. Shuvuuia deserti was flightless, turkey-sized, walked on two legs, had a long tail and neck, and had short forearms ending in a single, blunt claw. Later specimens have shown a reduced second and third finger.

Although it was more advanced than the earlier Archaeopteryx lithographica, Shuvuuia deserti did not look like a stereotypical modern bird, leading paleontologists to conclude that birds in the Late Cretaceous period were as diverse as they are today. Although many of these primitive species during the Cretaceous were quite different, they did have some unique characteristics found in modern birds. In the case of Shuvuuia deserti, the similarity was prokinesis—the up and down, independent movement of the snout that allowed the mouth to open wide.