Mysterious Dinosaur Anzu Debuts

Of all western North America’s fossiliferous lands, the Hell Creek Formation is among the richest boneyards. The 68-66 million year old exposures that stretch from Wyoming through Montana and the Dakotas have yielded countless dinosaurs, including the Cretaceous celebrities Edmontosaurus, Triceratops, and Tyrannosaurus. So much has been found that the chances of finding new, large dinosaurs are relatively slim, and many paleontologists have shifted their focus to investigating the biology of the formation’s abundant dinosaurs. Yet the Hell Creek isn’t totally tapped out yet. A bizarre dinosaur announced just this week shows that the famous formation still holds secrets.

Described by paleontologists Matt Lamanna, Hans-Dieter Sues, Emma Schachner, and Tyler Lyson in PLoS One, the new dinosaur is officially named Anzu wyliei. Journalists have had more fun crowing the creature’s nickname. Anzu was the “Chicken from Hell” – an eleven-foot-long Cretaceous weirdo with a toothless beak, a flashy crest, and elongated arms tipped with nasty-looking claws, all wrapped up in a coat of prehistoric plumage.

A reconstruction of Anzu with postcranial bones (figured in gray on the skeleton). Image from Lamanna et al., 2014.
A reconstruction of Anzu with postcranial bones (figured in gray on the skeleton). Image from Lamanna et al., 2014.

In the tangled branches of the dinosaur family tree, Anzu was an oviraptorosaur. These superficially bird-like, omnivorous dinosaurs have been found at other Cretaceous sites in North America and Asia, but to find a giant form hiding in the Hell Creek Formation was a surprise. That’s why paleontologists and dinosaur fans spent a decade and a half anxiously waiting for this dinosaur to be published.

The first two partial skeletons of Anzu were discovered in 1999 by Fred Nuss and Robert Detrich as they searched for 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. Word was getting out about the amazing oviraptorosaur when Scott Haire found another partial skeleton on a private ranch in North Dakota that went to a growing research collection in the town of Marmarth.

Anzu at the Carnegie Museum of Natural History. Photo by Brian Switek.
Anzu at the Carnegie Museum of Natural History. Photo by Brian Switek.

Reconstructions of the dinosaur’s skeleton only generated more buzz. Not only did the Carnegie Museum of Natural History in Pittsburgh acquire the first two skeletons, but they also put up a mount of Anzu made by Triebold when they reopened their renovated dinosaur halls in 2008. That mount became the basis for other, scrappier oviraptorosaurs discovered in western North America. The Natural History Museum of Utah’s mount of Hagryphus – an earlier oviraptorosaur as yet known from less material – has casts of some Anzu bones to help fill out the skeleton.

Anzu is no longer the dinosaur who must not be named. That alone is enough cause for celebration. Even better is that in the space of 15 years, Anzu has gone from being invisible to an exceptionally well-represented dinosaur. In addition to the three specimens already collected, a Burpee Museum of Natural History crew uncovered what’s likely a fourth Anzu skeleton. Anzu is well on its way to becoming a Hell Creek star.

But most important of all is the lesson Anzu teaches about what’s yet to be discovered. If such a superlative feathery weirdo could remain hidden for so long, who knows what’s still out there awaiting discovery?

Related Stories:

“Pearl” the Mystery Dinosaur
Did Feathered Dinosaurs Shake Their Tail Feathers?


Lamanna, M., Sues, H-D., Schachner, E., Lyson, T. 2014. A new large-bodied oviraptorosaurian theropod dinosaur from the Latest Cretaceous of western North America. PLoS ONE. 9, 3: e92022. doi:10.1371/journal.pone.0092022

10 thoughts on “Mysterious Dinosaur Anzu Debuts

  1. I didn’t know that about Hagryphus. amazing! I am going to pass that information along to all my coworkers, now!

  2. THIS is an extraordinary new species of oviraptosaur, especially in North America! So that skeleton in Carnegie Museum once thought to be from a possible species of Chirostenotes is actually an Anzu! Congratulations Lamanna et al.! Hooray, now we have another official animal from Hell Creek Formation along with Acheroraptor!

  3. Good question, Dan; I guess it all depends on whether Haegryphus’ hand is actually diagnostic or not. That is, does it have features that are indistinguishable from other oviraptorosaurs? If so, and if it shares those features with Anzu, then yes, Haegryphus should have priority. However, if those features are widely-spread in oviraptorosaurs (or caegnathids), then it should be considered a nomen dubium.

    It could also be that any features shared by Haegryphus and Anzu simply mean they’re each-other’s closest relatives, and the rest of the skeleton or skull may differ considerably. This is the problem when you name an entire genus based on A SINGLE HAND.

  4. I think there’s some misunderstanding about Hagryphus and Anzu. All Brian was saying is that the mount of Hagryphus on display at the Natural History Museum of Utah uses casts of the bones of Anzu to fill in the missing pieces. No one is saying they’re the same species. In fact, they’re separated in time by 10 million years, so its very unlikely.

    I should point out that the type of Hagryphus is represented by a hand and foot. And although this is scrappy material, there’s no need to get all fanboy indignant about it Zach. Based on our current understanding of caenagnathids, Hagryphus is very much diagnostic and valid. There are very good reasons for giving names to diagnostic but fragmentary material, especially for taxa that in the fossil record tend to be quite rare. Caenagnathids are a great example – most of the taxa from North America are very poorly known, but their morphology is so weird and disparate that we can generally tell when we’re dealing with different species. Just look at how long people have been collecting fossils from the Hell Creek Formation and how many fossils they’ve collected before someone found something as complete as Anzu. If we waited that long to name a new caenagnathid species in other formations, we’d never end up putting names on specimens, even though we knew they were something different from known species. Science is a process – and the naming of a new species is a hypothesis to be tested with new data. As such, there’s nothing wrong with naming fragmentary but diagnostic remains; one is proposing a hypothesis of a new species that will be tested by future fossil discoveries.

  5. Oh, c’mon, has every one got feathers on their brains? — there weren’t any feathers found with any of these skeletons, and the assumption that they were “covered” in feathers is mostly based on “related” fossils that were preserved much earlier, were much smaller and different in other ways and/or were several cladistic nodes away — leaving all sorts of opportunity for evolution to make drastic changes in integuement, produce feathers in other lines in parallel but not necessarily this one, etc. Just look at the figure in the original PLoS ONE report that shows where the fossils were found as well as the phylogenetic tree.

  6. @DavidBump So far literally every single taxa within coelurosauria that was well preserved enough for soft tissue to be preserved has had feathers and/or proto-feather fuzz. It’s silly to say “there weren’t any feathers found with any of these skeletons” as an argument. If you were to find a giant Pleistocene sloth skeleton isn’t it safe to assume that it had fur? No evidence of that is seen from the fossils. But we know that it was a mammal, and mammals tend to have fur. Through the same evolutionary logic we know that of Anzu had feathers based on it’s closest relatives (All of which had feathers). literally every type of coelurosaur including Tyrannosaurids (Dilong, yutyrannus) , Deinonychosauria (MIcroraptor, Velociraptor, archaeopteryx, Aurornis, Anchiornis, etc.) Oviraptorosauria (Incisivosaurus, Citipati, etc.) avialae (birds…nuf said), Therizinosauridae (Beipiosaurus) Ornithomimosauria (Ornithomimus) etc. with the right conditions has proven to had feathers. By the way from the family tree in the paper it’s clear that Caenagnathidae is nestled between feathered birds and feathered Oviraptorids. By the way Oviraptorisauria is the single closest non avian Theropod group to birds. I rest my case.

    1. Lots of mammals don’t have hair that you’d notice at a distance – elephants, rhinos, naked mole rats, and possibly even the odd giant sloth, at least those suspected of being more or less aquatic. Also, I specified my beef was with the enthusiastic assumption of this critter being “covered” with feathers. Many of the examples of “feathered” dinosaurs include those with a covering we can’t be sure was homologous to bird feathers, and/or did not constitute a covering type of integuement. Dilong had a “filamentous integumentary” called “proto-feathers,” Yutyrannus also had “feathers” described as “filament-like” structures, “simple filaments” and “the team’s measurements of the oxygen isotope ratios in the creatures’ teeth, a sensitive paleo-thermometer, suggest that the climate where these dinosaurs lived probably averaged about 10° Celsius over the course of a year—substantially colder than most of the dinosaur era, and in fact close to that seen in northeastern China today, Xu notes.” (, Researchers Unearth Largest Feathered Dinosaur, by Sid Perkins on 4 April 2012) The Deinonychosauria were all much smaller, mostly earlier, and often were either flying or gliding. The one, somewhat (not very) large, late exception, velociraptor, has no evidence for feathers except for possible quill knobs on the forelimbs. Incisivosaurus is a small oddity — and what source says it was found with feathers? Was one found with much more than the skull and a cervical? The Wikipedia article (FWIW) says a 2009 study indicates “…that the most birdlike features of oviraptorosaurs may have been convergent with birds.” Hmmm, convergence, where have I heard that before? Wiki (and other sources) also suggest the critter might be Caudipteryx or something very close. I can’t find any evidence for feathers on Citipati except the assumption that since it was found in a “brooding position,” it must have had feathers in order to actually cover all the eggs. You know, there are snakes that incubate their eggs and they don’t have feathers. Beipaosaurus (ONE of the oddball Therizinosuars) was relatively small and again has only traces of some filamentous material around some parts, assumed to be homologous with feathers. Ornithomimus again had downy markings around it, and possible quill attachment points on the forelimb. I’ve seen enough cladistic trees to know that what are closest groups today may be much farther apart when the next analysis is done.
      I continue to prefer to leave such cases open rather than join everyone else in closing their minds around a highly-desired and easy conclusion, steel-traplike or otherwise.

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