Description and Classification

Anzu was a relatively large dinosaur for its group, reaching lengths of about 3 to 3.5 meters (10 to 11.5 feet) and standing around 1.5 meters (5 feet) tall at the hips. It is estimated to have weighed between 200 and 300 kilograms (440 to 660 pounds). Anzu walked on two long legs and had a body plan that shared many similarities with modern birds, though it was much larger.

One of Anzu’s most striking features was a tall, rounded crest on top of its skull, similar to that of a cassowary. It had a toothless beak, long arms with three-fingered hands equipped with sharp claws, and a long tail. While direct feather fossils have not been found with Anzu specimens, its close relatives within Oviraptorosauria are known to have been feathered, so scientists believe Anzu was also covered in feathers.

Anzu belongs to the clade Oviraptorosauria, a group of feathered, bird-like theropod dinosaurs. More specifically, it is classified within the family Caenagnathidae. Caenagnathids, like Anzu, were generally larger than their close relatives, the oviraptorids (such as Oviraptor), and are primarily known from North America and Asia. Other members of the Caenagnathidae family include Caenagnathus and Chirostenotes.

Distinguishing Features

Anzu can be recognized by several key characteristics:

• A prominent, cassowary-like crest made of thin bone on the top of its skull.
• A parrot-like, toothless beak.
• Long, slender arms ending in three-fingered hands with sharp claws.
• A relatively large body size compared to many other oviraptorosaurs.
• Long legs adapted for running, suggesting it was an agile animal.
• Likely presence of feathers covering its body, inferred from related dinosaurs.

Paleoenvironment and Diet

Anzu lived in the Hell Creek Formation environment of the very late Cretaceous period. This ecosystem was a warm, humid coastal plain with rivers, forests, and swamps. Anzu shared this habitat with many well-known dinosaurs, including the fearsome Tyrannosaurus rex, the horned Triceratops, the duck-billed Edmontosaurus, and the dome-headed Pachycephalosaurus. The diverse plant life would have supported a complex food web.

The exact diet of Anzu is not certain because it had a toothless beak. However, most scientists believe it was an omnivore. This means it likely ate a variety of foods, possibly including plants, seeds, fruits, small animals like lizards and mammals, and perhaps eggs. Its agile build and clawed hands would have allowed it to forage effectively and possibly catch small prey. Its size might have also deterred some smaller predators.

Significance and Ongoing Research

The discovery of Anzu, specifically the species Anzu wyliei, was very important because it provided some of the most complete skeletons of a North American oviraptorosaur. Previously, caenagnathids were known mostly from scattered bones, making it difficult to understand what they looked like. Anzu helped confirm that these dinosaurs were indeed very bird-like, with crests and likely feathers, and provided a clearer picture of their anatomy.

Ongoing research on Anzu continues to shed light on the diversity and evolution of oviraptorosaurs. Scientists are studying its bones to learn more about its growth, how it moved, and the possible function of its crest, which might have been used for display to attract mates or intimidate rivals. Comparing Anzu to other oviraptorosaurs from North America and Asia helps researchers understand how this group of dinosaurs spread and changed over time. Future fossil finds may provide more direct evidence of its diet and behavior in the rich Hell Creek ecosystem.