In spite of its familiarity, it is known from far fewer remains than its closest relatives. In 2017 the Canadian paleontologists Victoria M. Arbour and Jordan Mallon redescribed the genus in light of newer ankylosaur discoveries, including elements of the holotype that had not been previously mentioned in the literature (such as parts of the skull and the cervical half-rings). They concluded that though Ankylosaurus is iconic and the best-known member of its group, it was bizarre in comparison to related ankylosaurs, and therefore not representative of the group. Many traditional popular depictions show Ankylosaurus in a squatting posture and with a huge tail club being dragged over the ground. Modern reconstructions show the animal with a more upright limb posture and with the tail held off the ground. Likewise, large spines projecting sideways from the body (similar to those of nodosaurid ankylosaurs) are present in many traditional depictions, but are not known from Ankylosaurus itself. The armor of Ankylosaurus has often been conflated with that of Edmontonia (earlier referred to as Palaeoscincus); in addition to Ankylosaurus being depicted with spikes, Edmontonia has also been depicted with an Ankylosaurus-like tail club (a feature nodosaurids did not have), including in a mural by the American artist Charles R. Knight from 1930. Description Ankylosaurus was the largest-known ankylosaurine dinosaur and possibly the largest ankylosaurid. In 2004 Carpenter estimated that the individual with the largest-known skull (specimen CMN 8880), which is long and wide, was about long and had a hip height of about . The smallest-known skull (specimen AMNH 5214) is long and wide, and Carpenter estimated that it measured about long and about tall at the hips. The American paleontologist Roger B. J. Benson and colleagues estimated the weight for AMNH 5214 at in 2014. In 2017, based on comparisons with more complete ankylosaurines, Arbour and Mallon estimated a length of for CMN 8880, and for AMNH 5214. Though the latter is the smallest specimen of Ankylosaurus, its skull is still larger than those of any other ankylosaurins. A few other ankylosaurs reached about in length. Because the vertebrae of AMNH 5214 are not significantly larger than those of other ankylosaurines, Arbour and Mallon considered their upper range estimate of nearly for large Ankylosaurus too long, and suggested a length of instead. Arbour and Mallon estimated a weight of for AMNH 5214, and tentatively estimated the weight of CMN 8880 at