Anodontosaurus

Anodontosaurus was named by Charles Mortram Sternberg in 1928, based on holotype CMN 8530, a partially preserved skeleton including the skull, half ring, armor and other postcranial remains. The badly crushed The generic name means "toothless lizard" in Ancient Greek. It was inspired by the fact that compression damage to the specimen had removed the teeth, at the same time shifting various flat round elements below the skull and on top of the left lower jaw, misleading Sternberg into assuming that large "trituration plates" had replaced the normal dentition. The specific name, lambei, honours Lawrence Morris Lambe, the Canadian geologist and palaeontologist from the Geological Survey of Canada where the holotype was reposited. ==Description==

Anodontosaurus was a medium-sized ankylosaurid, measuring up to in length and in body mass. It was a quadrupedal, ground-dwelling herbivore. Like other ankylosaurs, Anodontosaurus has armor on a majority of the dorsal surfaces of its body. It has a wide, pointed tail club at the end of its armored tail. The skull features postocular caputegulae, which are small polygonal plates of bone that are present on the cranium and are situated to the immediate rear of the eye. Coombs supported the assertion that specimen AMNH 5266 represented a juvenile by citing that the vertebral centra were not fused to their neural arches, and that sacral ribs were likewise not fused to vertebrae and to the ilium. Other morphological characters supporting that this is a juvenile specimen include (a) long bones that feature smooth surfaces, which are not marked by the rugosities characteristic of adult bone; (b) the head of the femur is less spherical in shape and is clearly delimited from the adjacent part of the femoral shaft; (c) the distal ends of the tibia and the fibula are not fused to the astragalus and the calcaneum; and (d) the ungual phalanx of the manus is not widest at the proximal articular end as is observed in adults. ==Classification==

In 1971, Walter Coombs concluded that there was only one species of ankylosaurid during the Campanian age of the Late Cretaceous of North America. He synonymised the species Anodontosaurus lambei, Dyoplosaurus acutosquameus, and Scolosaurus cutleri with Euoplocephalus tutus. The synonymisation of Anodontosaurus lambei and Euoplocephalus tutus was generally accepted and thus CMN 8530 was assigned to E. tutus. The second study, by Penkalski (2013), named and described Oohkotokia from Montana on the basis of remains that were originally thought to be referable to Euoplocephalus. Penkalski (2013) performed a small phylogenetic analysis of some ankylosaurine specimens. The only Anodontosaurus specimen that was included in this analysis was its holotype. Anodontosaurus was placed in a polytomy with the holotype of Euoplocephalus and some specimens that are referred to it, while Oohkotokia was placed in a clade with Dyoplosaurus, and specimens that are thought to represent either Dyoplosaurus or Scolosaurus. The DPF specimen, however, was later made the holotype of a new species, A. inceptus. The following cladogram is based on a 2015 phylogenetic analysis of the Ankylosaurinae conducted by Arbour and Currie: }} ==See also==