of between 76.2 and 75.2 million years. According to Theropoda Expeditions, it was 99% complete. It was described as a "dinosaur mummy", due to its preservation of soft tissues. Many osteoderms and small ossicles of the armour are present in their original position. Additionally, there are remains of keratin sheaths of the spikes and of keratin, non-bony, scales, in the form of a black film. The specimen is, as of 2017, the most complete ankylosaur find from the Judith River Formation. It was also the first North American ankylosaur specimen with well-preserved material from both the skull and tail. Description Zuul has been estimated to have been long, with a weight of . The describing authors of Zuul, Victoria Arbour and David Evans, noted some distinguishing traits of Zuul. Some of these were autapomorphies, unique characters which set Zuul apart from all other known ankylosaurids. The caputegulae, armour tiles of the head, that lay on the nasal bones, the frontals and the parietals, are imbricated, overlapping, and pointed on top. The squamosal horns, on the rear corners of the skull roof, have conspicuous longitudinal grooves on their side surfaces. The osteoderms on the side of the tail, the knob itself excepted, have a front edge with a strongly hollow profile, while their points are off-set to the rear. The tail knob is vertically flattened with a height less than a fifth of the length. Other traits were not unique but distinguished Zuul from various relatives in the Ankylosaurinae. The caputegulae on the prefrontals, the frontoparietals and the middle supraorbitals are pyramid-shaped, in contrast to the conical caputegulae with Nodocephalosaurus and Talarurus. The squamosal horn protrudes to behind the rear edge of the skull roof, just as with Scolosaurus but different from Anodontosaurus, Euoplocephalus or Ziapelta. The caputegulae behind the eye socket are small and sparsely distributed, again like Scolosaurus but differing from Anodontosaurus, Euoplocephalus or Ziapelta. The osteoderms on the handle of the tail club are relatively larger and more pointed than those of Asian ankylosaurines of the Nemegt Formation of Mongolia. Cranial anatomy With a length of about , the skull of Zuul is of considerable size, being only surpassed among the ankylosaurs of Laramidia (western North America) by the three known skulls of Ankylosaurus, specimens AMNH 5214, AMNH 5895 and CMN 8880. The skull is also rather flat but this is partly caused by compression. The snout is