Anzu (named for Anzû, a bird-like daemon in Ancient Mesopotamian religion) is a monospecific genus of caenagnathid dinosaur from North Dakota, South Dakota and Montana that lived during the Late Cretaceous (upper Maastrichtian stage, 67.2-66.0 Ma) in what is now the Hell Creek Formation. The type species and only species, Anzu wyliei is known from numerous skeletons that preserve cranial and postcranial elements. It was named in 2014 by Matthew C. Lamanna, Hans-Dieter Sues, Emma R. Schachner, and Tyler R. Lyson. It was named one of the "Top 10 New Species" for new species discovered in 2014 by the International Institute for Species Exploration in 2015. History of discovery Several large skeletons from the late Maastrichtian Hell Creek Formation of Montana and South Dakota were initially referred to as "cf. Chirostenotes", though more recent studies concluded that they represent new species. In 1998 Fred Nuss of Nuss Fossils discovered the site containing the holotype, CM 78000. The first two partial skeletons of Anzu were discovered in 1998 by Fred Nuss Fossils on a private South Dakota ranch. The two specimens weren't buried together – the skeletons rested about 330 feet apart with the second individual in a rock layer about 11 feet below the first – but, once prepped by the commercial outfit Triebold Paleontology, it was clear that both represented the same dinosaur. Both were mostly disarticulated and appeared to have been transported by a water current. A third referred specimen, fragmentary skeleton MRF 319, studied by Tyler Lyson of the National Museum of Natural History, was discovered by Scott Haire, who spotted the bones at his uncle's ranch at Marmarth, North Dakota. A rear lower jaw fragment, FMNH PR 2296, was also referred. These four fossils found at Hell Creek together make up a fairly complete skeleton of Anzu wyliei, comprising about 75 to 80 per cent of the whole skeleton. Three researchers, Emma Schachner of the University of Utah, Matthew Lamanna of the Carnegie Museum of Natural History and Tyler Lyson of the Smithsonian in Washington realized in 2006 that they each had partial skeletons of the same species and began collaborating to study it, assisted by Hans-Dieter Sues, a paleontologist at the National Museum of Natural History of the Smithsonian Institution in Washington. The main fossils are being held at the Carnegie Museum of Natural History in Pittsburgh. The genus is notable as the first well-preserved