Glyptotherium

Glyptotherium Temporal range: Early Pliocene-Late Pleistocene (Blancan-Rancholabrean) (Ensenadan-Lujanian) ~3.6–0.015 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
G. texanum, National Museum of Natural History
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Cingulata
Family:	Chlamyphoridae
Subfamily:	†Glyptodontinae
Genus:	†Glyptotherium Osborn, 1903
Type species
†Glyptotherium texanum Osborn, 1903
Other Species
† G. cylindricum (Brown, 1912)
Distribution of Glyptotherium (orange) compared to Glyptodon's (green).
Synonyms
Boreostracon Simpson, 1929 Brachyostracon Brown, 1912 Xenoglyptodon Meade, 1953 Synonyms of G. texanum Glyptotherium arizonae Gidley, 1926 Xenoglyptodon fredericensis Meade, 1953 Glyptodon fredericensis (Meade, 1953) Synonyms of G. cylindricum Glyptodon mexicanum Cuatáparo and Ramírez, 1875 Glyptodon nathorsti Felix and Lenk, 1875 Glyptodon petaliferus Cope, 1888 Brachyostracon cylindricum Brown, 1912 Brachyostracon mexicanum (Cuatáparo and Ramírez, 1875) Glyptodon rivipacis Hay, 1923 Boreostracon floridanus Simpson, 1929 Glyptotherium floridanum Simpson, 1929 Glyptotherium mexicanum (Cuatáparo and Ramírez, 1875)

Glyptotherium (from Greek for 'grooved or carved beast') is a genus of glyptodont (an extinct group of large, herbivorous armadillos) in the family Chlamyphoridae (a family of South American armadillos) that lived from the Early Pliocene, about 3.6 million years ago, to the Late Pleistocene, around 15,000 years ago. It had a wide distribution, living in the United States, Mexico, Guatemala, Costa Rica, Honduras, El Salvador, Panama, Venezuela, and Brazil. The genus was first described in 1903 by American paleontologist Henry Fairfield Osborn with the type species being, G. texanum, based on fossils that had been found in the Pliocene Blancan Beds in Llano Estacado, Texas, USA. Glyptotherium fossils have since been unearthed from many more fossil sites, from Florida to Colombia. Another species, G. cylindricum, was named in 1912 by fossil hunter Barnum Brown on the basis of a partial skeleton that had been unearthed from the Pleistocene deposits in Jalisco, Mexico. The two species differ in several aspects, including age, with G. texanum being from the older Early Pliocene to Early Pleistocene strata, whereas G. cylindricum is exclusive to the Late Pleistocene.

Glyptotherium was a large, quadrupedal (four-legged), herbivorous armadillo with an armored carapace (top shell) that was made of hundreds of interconnected osteoderms (structures in dermis composed of bone). Other pieces of armor covered the tail and cranium roof, the skull being tall with hypsodont (high-crowned) teeth. As for the postcranial anatomy, pelves fused to the carapace, an amalgamate vertebral column, short limbs, and small digits are characteristic of Glyptotherium and its relatives. Glyptotherium reached up to 2 meters (6.56 feet) long and 400 kilograms (880 pounds) in weight, making it one of the largest glyptodonts but not as large as its close relative Glyptodon or Doedicurus, the largest known glyptodont. Glyptotherium is morphologically and phylogenetically most similar to Glyptodon, however they differ in several ways. Glyptotherium is smaller on average, with a shorter carapace, a relatively longer tail, and a slender zygoma, or cheek bone.

Glyptodonts evolved first during the Eocene, but greatly diversified in the Miocene and Pliocene, largely in the Santacrucian sites of Argentina. However, their diversity diminished into the Pleistocene, though they peaked in size during this period. Glyptotherium is considered an example of North American megafauna, of which most have become extinct, and may have been wiped out by changing climate or human interference. Glyptotherium was primarily a grazer, but also had a mixed diet of fruits and other plants, that lived on open grasslands. The armor could protect the animal from predators, of which many coexisted with Glyptotherium during its existence, including the "saber-tooth cat" Smilodon, the "bone-crushing dog" Borophagus, and the "short-faced bears" (Tremarctinae).