''Urumacocnus'' is an extinct genus of

megalonychid Megalonychidae is an extinct family of sloths including the extinct ''Megalonyx''. Megalonychids first appeared in the early Oligocene, about 35 million years (Ma) ago, in southern Argentina (Patagonia). There is actually one possible find dating ...

sloth Sloths are a group of Neotropical xenarthran mammals constituting the suborder Folivora, including the extant arboreal tree sloths and extinct terrestrial ground sloths. Noted for their slowness of movement, tree sloths spend most of their li ...

that lived during the

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...

. The genus contains one known species, ''Urumacocnus urbanii''. Fossils have been found in the

Urumaco Formation The Urumaco Formation is a formation in Venezuela that includes deposits from the Late Miocene. It is the site of several "giant forms": the turtles, crocodiles, sloths and rodents of Urumaco are among the largest of their groups. Location Th ...

of Venezuela.

Etymology

The generic name, ''Urumacocnus'', is derived from the Urumaco Formation in which its fossils have been found in, and -ocnus, which means "hesitating" or "lazy", which is commonly used to name extinct sloths. The specific name honours Franco Urbani, for his important contributions to Venezuelan geology.

Description

''Urumacocnus'' is a relatively small sized megalonychid sloth that shares a combination of diagnostic features such as a round femur shaft, a straight femur shaft, albeit with the medial and lateral sides curved the femur head angle with respect to the femur shaft which is more than 160°, the femur neck being well demarcated, a valley between the femur head and the greater trochanter shallow; the

femoral head The femoral head (femur head or head of the femur) is the highest part of the thigh bone (femur). It is supported by the femoral neck. Structure The head is globular and forms rather more than a hemisphere, is directed upward, medialward, and a l ...

present and larger than in other members of the family; the proximal end of the femur being broader than the distal end, greater trochanter longer than wide and smaller than the head, and entirely positioned distal to the femur head; and the lesser

trochanter A trochanter is a tubercle of the femur near its joint with the hip bone. In humans and most mammals, the trochanters serve as important muscle attachment sites. Humans are known to have three trochanters, though the anatomic "normal" includes ...

well developed, and caudally and medially directed.

Taxonomy

References

{{Taxonbar, from=Q112259853 Prehistoric sloths Miocene xenarthrans Miocene mammals of South America Neogene Venezuela Fossils of Venezuela Huayquerian Chasicoan Mayoan Fossil taxa described in 2019 Prehistoric placental genera