The fossil was rediscovered in January 2006 by graduate student Sterling Nesbitt at the American Museum of Natural History. Nesbitt was opening jackets of blocks in order to find new specimens of Coelophysis. Upon finding the remains of Effigia, he instantly recognized this was not a dinosaur and proceeded to track down the rest of the blocks from that area of the quarry. 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.
Effigia is noted for its remarkable similarity to ornithomimid dinosaurs. Nesbitt, in 2007, showed that Effigia was very similar to Shuvosaurus, and is definitely a member of the crurotarsan group Suchia (in the line leading towards modern crocodilians), and that its similarity to ornithomimids represents a case of "extreme" convergent evolution. Nesbitt also demonstrated that Shuvosaurus was the same animal as Chatterjeea, and that it belonged to an exclusive clade containing closely related suchians such as Shuvosaurus and Poposaurus (Poposauridae). Within this group, Effigia forms an even more exclusive clade with Shuvosaurus and the South American Sillosuchus (Shuvosaurinae). In 2007, Lucas and others suggested "Effigia" was synonymous with "Shuvosaurus" and used the new combination "Shuvosaurus okeeffeae" for the animal.
In popular culture
- In a January 30, 2006 episode of The_Colbert_Report, Stephen_Colbert satirically touted the fossil as disproving the "Darwinlutionists" ("who try to claim that every kind of creature had evolved from monkeys"). Colbert also believes that the fossil should not have been named after Georgia O'Keeffe, whose paintings "scare the hell out of [him]", and instead should have been named after Edwin H. Colbert (see List of The Colbert Report episodes).
- In the 2007 IMAX 3D film, Dinosaurs Alive!, Nesbitt explains how he discovered Effigia. It is also featured in an animated sequence where it is chased by a small pack of Coelophysis and was later killed by a Redondasaurus.
- It was also seen in one episode of Dinosaur Train "Classic in the Jurassic" in a Crocodile contest. Air, Water & Land.