''Megistonyx'' is an extinct genus of ground sloth endemic to South America during the Late Pleistocene (

Lujanian The Lujanian age is a South American land mammal age within the Pleistocene and Holocene epochs of the Neogene, from 0.8–0.011 Ma or 800–11 tya. It follows the Ensenadan. The age is usually divided into the middle Pleistocene Bonaerian stag ...

). It is known from one skeleton collected in the Andes of

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 ...

, and is closely related to '' Ahytherium''.

History of discovery

The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...

(and so far only known) specimen was found in a cave called ''Cueva de los Huesos'' (meaning "Bone Cave") on Cerro Pintado, a mountain found in the

Serranía del Perijá The Serranía del Perijá, Cordillera de Perijá or Sierra de Perijá is a mountain range, an extension of the eastern Andean branch ( Cordillera Oriental), in northern South America, between Colombia and Venezuela Venezuela (; ), offici ...

range of the

Andes The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...

, in the extreme northernmost part of the

Sierra de Perijá National Park Sierra de Perijá National Park, also known as Perijá National Park, is a protected area in Venezuela. It is located in the Serranía de Perijá mountains on the border with Colombia, to the southwest of Zulia state and Lake Maracaibo. The park wa ...

on the border between Venezuela and Colombia at an altitude of . The various known pieces of the skeleton were recovered in two expeditions to the cave in 1993 and 1997. The specimen was found in a scattered condition, with some bones being damaged, notably the skull was missing the left

Squamosal bone The squamosal is a skull bone found in most reptiles, amphibians, and birds. In fishes, it is also called the pterotic bone. In most tetrapods, the squamosal and quadratojugal bones form the cheek series of the skull. The bone forms an ancestral c ...

. The specimen is currently known from the aforementioned skull, both a right and left humerus, a left

ulna The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...

, two

thoracic vertebrae In vertebrates, thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. In humans, there are twelve thoracic vertebrae and they are intermediate in size between the cervical ...

, a complete rib and three rib fragments. There is apparently more of the specimen left in-situ in the cave. The age of the specimen was found to be approximately 17,300

Cal BP Before Present (BP) years, or "years before present", is a time scale used mainly in archaeology, geology and other scientific disciplines to specify when events occurred relative to the origin of practical radiocarbon dating in the 1950s. Becau ...

Distribution and habitat

The specimen is approximately 17,000 years old, this would put the specimen just after the retreat of the glaciers after the Last Glacial Maximum, which could indicate a cold climate. However, the specimen is associated with fossils of ''

Neochoerus ''Neochoerus'' ("new hog") is an extinct genus of rodent closely related to the living capybara. Fossil remains of ''Neochoerus'' have been found through North America (México and United States) and South America in Boyacá, Colombia C ...

'' (an extinct capybara) '' Mazama'' (brocket deer) and ''

Tayassu The white-lipped peccary (''Tayassu pecari'') is a species of peccary found in Central and South America and the only member of the genus ''Tayassu''. Multiple subspecies have been identified. White-lipped peccaries are similar in appearance to ...

'' (peccary), which could indicate a warmer, perhaps savanna-like climate.

References

{{Taxonbar, from=Q30693620 Prehistoric sloths Prehistoric placental genera Pleistocene xenarthrans Holocene extinctions Pleistocene mammals of South America Lujanian Pleistocene Venezuela Fossils of Venezuela Fossil taxa described in 2013