the same Canyon Bone Bed site as MOR 485 (and catalogued under the same number), but only reported in 2010. Two other specimens were collected on the Blacktail Creek, to the south of Cut Bank and referred to Achelousaurus by Sampson in 1995. Specimen MOR 591 is a partial skull and an about 60% complete skeleton of a sub-adult specimen that includes the vertebral column, pelvis, sacrum and a femur. It also includes lower jaws, catalogued as MOR 591-7-15-89-1. Both skull and lower jaws are nearly complete, lacking only the braincase and occipital region. MOR 591 is smaller than the holotype with a skull base length of about . Specimen MOR 571 includes a partial skull and lower jaws with associated ribs and vertebrae of an adult. The skull consists of only the parietals, and the lower jaws are limited to their upper rear bones, the surangulars and articulars. A fifth specimen is MOR 456.1, a subadult. None of the specimens were of an advanced individual age. According to Andrew McDonald and colleagues, the Achelousaurus finds represented single individuals, not bone beds. Possible Achelousaurus finds In addition to fossils that have been unequivocally assigned to Achelousaurus, some other material has been found of which the identity is uncertain. A centrosaurine ceratopsid specimen with bosses from the Dinosaur Park Formation (specimen TMP 2002.76.1) found in 1996 was suggested to belong to a new taxon in 2006, but may instead belong to Achelousaurus or Pachyrhinosaurus. Since it is missing the parietal bones, which are used to diagnose centrosaurines, it is not possible to assign it to any genus with confidence. In 2006, it was also proposed that Monoclonius lowei, a dubious species based on a skull (specimen CMN 8790) from the Dinosaur Park Formation, could be a sub-adult specimen of Styracosaurus, Achelousaurus or Einiosaurus, with which it is roughly contemporaneous. In addition, some indeterminate specimens from the Two Medicine Formation – such as fragmentary skull MOR 464 or snout MOR 449 – may belong to Achelousaurus or the two other roughly contemporary ceratopsids Einiosaurus and Rubeosaurus. Description General build Achelousaurus is estimated to have been long with a weight of . The skull of an adult individual (holotype specimen MOR 485) was estimated to have been long. This puts it in the same size-range as other members of the Centrosaurinae subgroup of ceratopsians that lived during the Campanian age. It was about