With a bipedal stance, long neck, and a toothless beaked skull, Effigia and other shuvosaurids bore a resemblance to the ornithomimid dinosaurs of the Cretaceous Period.

Colbert's expedition intended to recover abundant fossils of the basal theropod dinosaur Coelophysis, and he believed that no other large vertebrates were present in the quarry.

The plaster jacket containing the holotype of Effigia started to be prepared in 2004, and the specimen was uncovered by graduate student Sterling Nesbitt at the AMNH.

Nesbitt and Mark Norell, curator at the museum, named it Effigia okeeffeae in January 2006 after Georgia O'Keeffe, who spent many years at Ghost Ranch.

In 2007, Nesbitt's description demonstrated that Effigia was very similar to Shuvosaurus, and is definitely a member of the archosaur subgroup Pseudosuchia (the line leading towards modern crocodilians).