Doh! You're not a dinosaur after all...

Galvasean

I suppose you could consider it a demotion of sorts... Azendohsaurus, once believed to be a primitive form of prosauropodomorph, is no longer considered a dinosaur. New research has shown that it is in fact a primitive type of archosauromorph. It's similarities to early dinosaurs are a case of convergent evolution.

“Even though this extraordinary ancient reptile looks similar to some plant-eating dinosaurs in some features of the skull and dentition, it is in fact only distantly related to dinosaurs,” says John J. Flynn, curator in the Division of Paleontology at the American Museum of Natural History. “With more complete material, we re-assessed features like the down-turned jaw and leaf-shaped teeth found in A. madagaskarensis (one species of Azendohsaurus) as convergent with some herbivorous dinosaurs.”

The fossil he mentions is now a member of Archosauromorpha, a group that includes birds and crocodilians, but not lizards, snakes, or turtles. The analyzed specimen was uncovered by a team of U.S. and Malagasy paleontologists in a “red bed” that includes multiple individuals that probably perished together. This species was initially published as an early dinosaur in Science over a decade ago, but the completeness of the more recently unearthed and studied fossils has provided the first complete glimpse of A. madagaskarensis as a reptile and not a dinosaur.

Full article here.




Other recent high profile examples of new reseach on old specimens leading to reclassification include the 'American lion' and Proceratosaurus.