Ahytherium

Ahytherium is an extinct genus of megalonychid sloth that lived during the Pleistocene of what is now Brazil. It contains a single species, A. aureum. The almost-complete skeleton of Ahytherium alongside remains another extinct sloth species, Australonyx, were discovered in Poço Azul, an underwater cave in Chapada Diamantina National Park in 2005. It was described by Castor Cartelle of Pontifícia Universidade Católica de Minas Gerais. The bones, which had a length of about when put together, belong to an animal which presumably was still growing. This animal is known from well-preserved and nearly complete fossils, including a skeleton of an immature specimen, which in life must have been about three meters long, one meter tall and weighing perhaps half a ton. Like all ground sloths, Ahytherium was equipped with a robust body and legs equipped with powerful claws. Ahytherium was similar to other ground sloths such as Megalonyx but possessed some features that clearly distinguished it: the head, for example, was extremely short and tall, and possessed dorsally swollen frontal bones. The zygomatic arches were wide, particularly the frontal processes, while the lacrimal bones were narrow, blade-shaped and directed anterolaterally. The dentition included canine teeth that were thin, curved and oval in cross-section. The humerus was equipped with a poorly developed deltopectoral crest, while the femur possessed a large trochanter located distally. The shape of the caudal vertebrae indicates that the tail was dorsoventrally flattened. Ahytherium is a genus of the extinct family Megalonychidae within the suborder Folivora and the superorder Xenarthra. The Megalonychidae represent a very diverse group. The closest relatives of the Megalonychidae are the Megatheriidae and the Nothrotheriidae. The former include the largest known representatives of the sloths, the latter consist of rather smaller members of the sloths. All three families together are relegated to the superfamily of Megatherioidea.