As in all known ankylosaurids, the foot has three toes, not four as Maryańska assumed in 1977, misled by the damaged specimen ZPAL MgD−II/9. The phalangeal formule of the toes is variable: most individuals have 0−3−3−4−0 but some exemplars possess an extra penultimate phalanx in the third toe, resulting in 0-3-4-4-0, while others lack a phalanx in the fourth toe, which causes a 0-3-3-3-0 configuration. The configuration of the skin ossifications, or osteoderms, of the body is partly known: no single specimen conserves a complete set. Additional information can be gleaned from the larger specimen MPC 100/1305, a possible "Pinacosaurus" exemplar. The neck is protected by two cervical halfrings, consisting of keeled rectangular segments fused to an underlying bone band. This band is completely ossified even in juvenile individuals. Godefroit assumed "Pinacosaurus" differed from other species in having three or four segments instead of the usual six, but Arbour concluded that the normal number was in fact present. The sides of the rump and the tail were occupied by moderately long, flat, recurved, triangular spikes. Parallel rows of smaller oval keeled osteoderms were present on the back. A continuous "sacral shield" on the hip, made of fused plates, is absent. Originally placed in the Nodosauridae by Gilmore, "Pinacosaurus" is now considered to be an ankylosaurid and a likely member of the Ankylosaurinae. As indicated by Thompson et al. 2012, the difference in the relative position of the two "Pinacosaurus" species between the respective analyses, is influenced by the fact that the best preserved "P. grangeri" skulls are from juveniles, while the holotype of "P. mephistocephalus" is an adult with a skull that is longer than it is wide, which might cause a more basal position of the latter. The following cladogram is based on the 2015 phylogenetic analysis of the Ankylosaurinae conducted by Arbour and Currie:  The habitat of "Pinacosaurus" consisted of a semi-desert interspersed with oases. No large theropods are known to have inhabited the ecosystem, though smaller ones like "Velociraptor" were present.