GLYPTODON (from the fluted character of its teeth), a gigantic fossil mammal, belonging to the order EDENTATA, and related to the megatherium and lnylodon, also closely allied in form and structure to the modern as well as ancient armadillos. The first notice of this fossil animal was published by Cuvier, in 1823, in an extract of a letter addressed by the cure of Montevideo to M. August St. Hilaire, describing several huge fossil bones, and portions of tesselated bony armor. Cuvier supposed them to belong to the megatherium, remarking that that animal bad pushed its analogies with the armadillo so far as to be covered like them with a scaly cuirass. The living families of daspodida3 and myrmecophagidm of South America were represented in the same geographical area in pliocene and post-pliocene times bvmany interesting types, most of which, though representatives of those now living, differed from them in points of generic importance, while many were of comparatively gigantic proportions. The glyp todon differs from the vuwatherium in the number and form of its teeth, and Rom the armadillos in the form of the lower jaw, and in the presence of a long process descending from the zygoma; but in these respects it resembles the megatherium. Four species of glyptodon have been described by prof. Owen, the largest of which is glyptodon clavipes. The back and sides were covered by an armor or "carapace," of thick polygonal bony plates, which were dermal ossifications or scales, to the number of 2,000 or more. The head was also covered with a helmet of similar construction, and the tail was inclosed in a cylindrical casing of similar polygonal plates, which were, as a rule, nearly hexag onal. The carapace formed a massive dome for the support of which the skeleton was specially adapted. Thus, the last cervical and first two dorsal vertebra; are anchylosed to form a single bone, which articulates by a hinge joint with the next dorsal. The sacral and caudal vertebrm form a bony mass, and the Mist are enormous, Unlike the living armadillos, the glyptodon has no movable bands in its •armor; and therefore could not, like them, roll itself up. The animal had no canines, but there were eight molars
on each side of each jaw. The feet were massive, the ungual phalanges short, com pressed, and hoof-like, the fore feet being tetradactylous, and the hind feet with four or live toes. The carapace of the glyptodon in the royal college of surgeons in London has the following dimensions: length 5 ft. 7 in. following the curve of the back, in a straight line 4 ft. 8 in.; breadth over curve, 7 ft. 4 in. ; in a straight line, 3 ft. 2 inches. The tail was 18 in. long, and 14 in. in circumference at the base. The dimensions of the glyptodou in the museum of natural history of Columbia college, New York, are as follows: entire horizontal length, frofii end of nose to tip of tail (of skeleton), 9 ft. 2 in ; . length of carapace, following the curve, 6 ft. 9 in.; transverse of carapace, following the curve, 9 ft. 1 in.; horizontal breadth, from edge to edge of carapace (which is less than at the middle), 3 ft. 5 in.; length of head, 14 in.; depth of head from occiput to angle of lower jaw, 14 in.; circumference of tail at base, 4 ft. 5 in.; length of tail, 3 ft. 10 inches. The genus schistopleuron comprises gigantic armadillos, which were contemporaries of the glypotodon. Schistopleuron typus was 8 ft. in length, including the tail, and the cara pace was 3 ft. in height. No direct representative of the glyptodon is known to exist at the Present day, but the true armadillos, having movable bands in.their armor, have been found in the post-tertiary accumulations of the plains of South America, and also of the cave deposits of Brazil. Some of them belong to well-known living types, as dasypus, zenurus, and eutatus, while others belong to extinct gigantic forms, as chalamydotherium and pachytherium, the former of these two attaining to the size of the existing rhinoceros. The ant-eaters also, inynnecophagidie, are represented in the cave deposits of Brazil by the extinct glossetheriurn. See ARMADILLO, ANT-EATER, and MEGATHERIUM.