Anzu wyliei

Anzu (named for Anzû, a bird-like daemon in Ancient Mesopotamian religion) is a genus of caenagnathid dinosaur from North Dakota, South Dakota, and Montana. This dinosaur lived during the Late Cretaceous (upper Maastrichtian stage, about 67.2 to 66.0 million years ago) in what is now the Hell Creek Formation. The main species, Anzu wyliei, is known from many skeletons that show both its skull and body parts. It was named in 2014 by scientists Matthew C. Lamanna, Hans-Dieter Sues, Emma R. Schachner, and Tyler R. Lyson.

Anzu was chosen as one of the "Top 10 New Species" discovered in 2014, showing how important this find was for science. In 2015, it was again recognized by the International Institute for Species Exploration as a very important discovery. Another unnamed species of this dinosaur was also found in Montana in the Hell Creek Formation, in Carter County. This dinosaur helps scientists learn more about life from that time long ago.

History of discovery

In 1998, a person named Fred Nuss found the first two partial skeletons of Anzu on a ranch in South Dakota. These skeletons were mostly scattered and had been moved by water. Another skeleton was later found by Scott Haire at his uncle’s ranch in Marmarth, North Dakota. These fossils, found together in the Hell Creek area, make up a fairly complete picture of Anzu wyliei, showing about 75 to 80 percent of its whole body.

Researchers from several museums studied these fossils and realized they belonged to the same species. They worked together to learn more about Anzu. This dinosaur is special because it is one of the best-preserved examples of a North American oviraptorosaur, helping scientists understand more about these ancient creatures. It had big crests on its skull, a beak instead of teeth, and a skeleton that looked very much like a bird. Because of this, it was nicknamed the “chicken from hell.” The name Anzu wyliei honors a person named Wylie J. Tuttle, whose grandparent helped support the museum where the fossils are kept.

Description

Anzu wyliei had a toothless beak, a noticeable crest on its head, long arms with big curved claws, strong legs with slender toes, and a short tail. This dinosaur measured about 3.5–3.75 metres (11.5–12.3 ft) long and stood up to 1.5 metres (4.9 ft) tall at the hips. It was one of the larger oviraptorosaurs found in North America.

When scientists first described Anzu, they found special traits that make it unique. It had a high, crescent-shaped crest on its skull, a wider occipital condyle compared to its foramen magnum, and a special shape on the front of its lower jaw. The lower jaw also had a long projection at the back. Other notable features included a divided lower end of the radius bone and a tubercle on the front of the ankle bone.

Classification

Anzu belonged to a group of dinosaurs called oviraptorosaurs, specifically within the family Caenagnathidae. Scientists used special methods to study its family tree and found it might be closely related to another dinosaur called Caenagnathus.

Before finding Anzu wyliei, experts thought oviraptorosaurs in North America would be similar to those in Asia because the two areas were connected by land long ago. However, this discovery shows that North American oviraptorosaurs were more closely related to each other than to those in Asia.

Paleobiology

Anzu was probably an omnivore or herbivore, though its beak wasn’t as strong as some other dinosaurs. It had thicker legs and different lower jaws compared to similar dinosaurs from Asia, which were smaller.

The fossils of Anzu wyliei were found in mudstone, a type of rock formed from old floodplains. This suggests that Anzu lived in a very different environment from its Asian relatives, who lived in dry or semi-dry areas. Experts describe Anzu as a fast-moving dinosaur that could eat many types of food, like plants, small animals, and maybe even eggs.

Though Anzu had some features similar to modern birds, it was not a bird dinosaur and went extinct 66 million years ago along with many other dinosaurs. Its bird-like traits are an example of convergent evolution, meaning it evolved similar features independently. Scientists say it likely showed many bird-like behaviors, bridging the gap between typical dinosaurs and birds.

The large crest on Anzu’s head had an unclear purpose, but it was very big and made of thin bone, so it likely wasn’t used for fighting. It might have been used to show off to others of its kind, much like some birds today. Fossils show signs of injuries, such as a healed broken rib, but it isn’t known if these came from fighting or from other dangers.