[1] Three fossils of Yutyrannus huali — all found in the rock beds of Liaoning Province — are the largest-known dinosaur specimens that preserve direct evidence of feathers.

[3] The holotype, ZCDM V5000, is the largest specimen, consisting of a nearly complete skeleton with a skull, compressed on a slab, of an adult individual.

The snout features a high midline crest, formed by the nasals and the premaxillae and which is covered by large pneumatic recesses.

[1] However, scaly skin impressions have been reported from various Late Cretaceous tyrannosaurids (such as Gorgosaurus, Tarbosaurus and Tyrannosaurus) on parts of the body where Yutyrannus was feathered.

[7] If scaly skin was the dominant epidermal trait of later genera, then the extent and nature of the integumentary covering may have changed over time in response to body size, a warmer climate, or other factors.

Primitive traits relative to advanced tyrannosaurs included long forelimbs with three fingers and a short foot which was not specialized for running.

[9] Their cladogram is shown below: Guanlong Proceratosaurus Kileskus Yutyrannus Sinotyrannus The knowledge of specimens representing various different ages has allowed paleontologists to determine the ontogeny, or change during growth, of this species.

[10] Because the three known individuals of Yutyrannus were allegedly found together, some paleontologists, including Xu Xing, have interpreted the animal as a pack hunter.

[11] If Yutyrannus did prey on sauropods, it would have been one of two predatory animals known from the Yixian formation capable of doing so, the other being an as-of-yet undescribed large theropod known from a tooth embedded in the rib of a Dongbeititan.

Age estimates point towards Yutyrannus originating from the Lujiatun or the Jianshangou beds of the Yixian, meaning it would have been contemporaneous of such dinosaurs as Psittacosaurus, Dongbeititan, Sinosauropteryx, and Caudipteryx.

Volcanic eruptions and forest fires appear to have been common in the Yixian, and the environment would have been littered with bodies of water and coniferous plants.

The environment would have been comparable to the modern day temperate rainforests of British Columbia, and would have experienced significant seasonal changes in temperature.