Dinosaurs - Yutyrannus huali

Introduction

Pronounced yoo-ti-RAN-us
Meaning beautiful feathered tyrant.

Named using the Mandarin word yu meaning feather and the Latin word tyrannosmeaning tyrant, a reference to the fact it is a feathered member of the Tyrannosauroidea superfamily. The species name is the Mandarin word huáli meaning beautiful, in reference to the beauty of the plumage.
This dinosaur was the first large tyrannosaurus found with feathers. Theories include that they possibly used feathers to keep warm in cold climate.

Identification

Yutyrannus is known from three specimens and holds the distinction of being the largest known dinosaur with direct evidence of feathers.The feathers were filaments, so looked like the fuzzy down of baby chicks, and served to keep the dinosaur warm in cooler periods. Yutyrannus had a distinctive nasal crest that was probably used for display.

Yutyrannus was a gigantic bipedal predator. The original (holotype) has a known length of 9 metres and an estimated weight of approximatley 1,400 kg. Its skull has an estimated length of 90 centimetres.

Scientists established some diagnostic traits of Yutyrannus, in which it differs from its direct relatives:-

The snout features a high midline crest, formed by the nasals and the premaxillae and which is covered by large pneumatic recesses. The postorbital has a small secondary process, jutting into the upper hind corner of the eye socket. The outer side of the main body of the postorbital is hollowed out. In the lower jaw, the external mandibular fenestra, the main opening in the outer side, is mainly located in the surangular.

Yutyrannus had a disctinctive nasal crest that was probably used for display.

Distribution

Reportedly found in what is now Liaoning province, China.

This large feathered tyrannosaur lived 131-120 million years ago during the Early Cretaceous.

Yutyrannus huali was named and described in 2012 by Xu Xing et al.after being purchased from a dealer in 2012.

Other behaviours and adaptations

Feathers
While it has been known since 2004, with the description of Dilong, that at least some tyrannosauroids possess filamentous “stage 1″ feathers. These are like the fuzzy down of baby chicks. According to the feather typology of Richard Prum, Yutyrannus huali is currently the largest known species of dinosaur with direct evidence of feathers, forty times heavier than the previous record holder, Beipiaosaurus.

The feathers were long (up to twenty centimetres) and filamentous. Because the quality of the preservation was low, it could not be established whether the filaments were simple or compound, broad or narrow. The feathers covered various parts of the body. With the holotype they were present on the pelvis and the foot, another specimen had feathers on the tail pointing backwards. The smallest specimen showed twenty-centimetre-long filaments on the neck and sixteen-centimetre-long feathers at the upper arm.Based on this distribution, feathers may have covered the whole body and served in regulating temperature. Alternatively, if the feathers were restricted to the regions in which they were found they may have served as display structures. In addition, the two adult specimens had distinctive, “wavy” crests on their snouts, on both sides of a high central crest, which were probably used for display. The presence of feathers on a large basal tyrannosauroid suggests the possibility that later tyrannosaurids were also feathered, even when adult, despite their size.

Fossils description

Yutyrannus is known from three nearly complete fossil specimens (an adult, a subadult and a juvenile) acquired from a fossil dealer who claimed all three had their provenance in a single quarry at Batuyingzi in Liaoning Province, China. They probably were found in a layer of the Yixian Formation, about 125 million years old. The specimens had been cut into pieces about the size of bath mats, which could be carried by two people.
The holotype, is the largest specimen, consisting of a nearly complete skeleton with skull, compressed on a slab, of an adult individual.

The paratypes are the two other specimens consisting of a skeleton of a smaller individual and a juvenile estimated to have been eight years younger than the holotype. The fossils are part of the collections of the Zhucheng Dinosaur Museum and the Erlianhaote Dinosaur Museum but have been prepared by the Institute of Vertebrate Paleontology and Paleoanthropology, under guidance of Xu.