Nothrotheriops Temporal range: Pleistocene, | |
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N. shastensis skeleton with preserved skin, Yale Peabody Museum | |
Restoration of N. shastensis | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Pilosa |
Family: | † Nothrotheriidae |
Subfamily: | † Nothrotheriinae |
Genus: | † Nothrotheriops Hoffstetter, 1954 |
Type species | |
†Nothrotheriops shastensis Sinclair, 1905 | |
Species | |
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Nothrotheriops is a genus of Pleistocene ground sloth found in North America, from what is now central Mexico to the southern United States. [1] This genus of bear-sized xenarthran was related to the much larger, and far more famous Megatherium , although it has recently been placed in a different family, Nothrotheriidae. [2] The best known species, N. shastensis, is also called the Shasta ground sloth.
Nothrotheriops fossils were first collected by the University of California's Anthropology Department during an exploration of caves at Potter Creek Cave in Shasta County, California, the fossils dating to the late Quaternary period. [3] [4] These first fossils (UCMP 8422), consisting of an incomplete mandibular ramus lacking teeth of an individual and 14 additional molars, were sent to the University of California Museum of Paleontology where they were described by paleontologist William Sinclair in 1904 as a new species of Nothrotherium, N. shastensis (species name meaning "from Shasta"). [3] 11 years later in 1916, Smithsonian paleontologist Oliver P. Hay named Nothrotherium texanus (species name meaning "from Texas") based on a partial skull that was transferred from Baylor University in Baylor, Texas. The skull had been collected in the Pleistocene strata of Wheeler County, Texas and given to a clergyman who then gave it to university staff in 1901. [4] [5] Many fossils were later referred to the two, but N. shastensis wasn't placed in a new genus until 1954 when it was placed in a new genus, Nothrotheriops ("near slothful beast", due to its similarity to Nothrotherium) by Robert Hoffstetter during a study of fossil sloths. [6] [4] N. texanus was recombined into the genus in 1995, and had many fossils referred to it from Florida, the easternmost occurrence of the genus. [4]
Fossils of the best-known species, the Shasta ground sloth (N. shastensis), have been found throughout western North America, especially in the American Southwest. It is the ground sloth found in greatest abundance at the La Brea Tar Pits. The most famous specimen was recovered from a lava tube at Aden Crater in New Mexico and was found to still have hair and tendon preserved. [7] This nearly complete specimen is on display at the Yale Peabody Museum of Natural History in New Haven, Connecticut. Numerous dung boluses belonging to Nothrotheriops have also been found throughout the southwestern United States and have provided an insight into the diet of these extinct animals.
This genus's lineage dates back to the Miocene. The ancestors of Nothrotheriops migrated to North America from South America as part of the Great American Interchange during the Blancan, about 2.6 MYA. [1]
Although N. shastensis was one of the smallest mainland ground sloth species, it still reached 2.75 metres (9.0 ft) from snout to tail tip and weighed 250 kilograms (551 lb) [8] (one-quarter of a tonne) – much smaller than some of its contemporary species such as the Eremotherium , which could easily weigh over two tonnes and be 6 metres (20 ft) long. [9] It had large, stout hindlegs and a powerful, muscular tail that it used to form a supporting tripod whenever it shifted from a quadrupedal stance to a bipedal one (i.e. Eremotherium ). [10]
Nothrotheriops behaved like all typical ground sloths of North and South America, feeding on various plants like the desert globemallow, cacti, and yucca. It was hunted by various local predators, like dire wolves and Smilodon , from which the sloths may have defended themselves by standing upright on hindlegs and tail and swiping with their long foreclaws, like its distant relative Megatherium , as conjectured in the BBC series Walking with Beasts . The same claws could also have been used as tools to reach past the plant spines and grab softer flowers and fruits. Also, the Shasta ground sloth may have had a prehensile tongue (like a giraffe) to strip leaves off branches. [10]
The Shasta ground sloth is believed to have played an important role in the dispersal of Yucca brevifolia , or Joshua tree, seeds. Preserved dung belonging to the sloth has been found to contain Joshua tree leaves and seeds, confirming that they fed on the trees. It has been suggested that the lack of Shasta ground sloths helping to disperse the seeds to more favourable climates is causing the trees to suffer. [11] [12]
A fossil find had been described from as far north as the Canadian province of Alberta; however, this report is believed to have been mistaken. [13] The genus lived primarily in the southwestern region of the U.S., from the states of Texas and Oklahoma to California; it has also been found in Florida. [1] [4]
The best known historical specimen was found in a lava tube at Aden Crater in New Mexico; it was found with hair and tendon still preserved. [7] The Rampart Cave, located on the Arizona side of the Lake Mead National Recreation Area, has a plentiful amount of the sloth's hair and dung, both of which scientists used for radiocarbon dating to establish when it lived. [10] The most recent credible dates from this and each of about half a dozen other southwestern caves are about 11,000 BP (13,000 cal BP). [14] In addition to North America, fossils assigned to Nothrotheriops sp. have also been found as far south as Argentina's Santa Fe Province. [15]
Megatherium is an extinct genus of ground sloths endemic to South America that lived from the Early Pliocene through the end of the Late Pleistocene. It is best known for the elephant-sized type species Megatherium americanum, primarily known from the Pampas, but ranging southwards to northernmost Patagonia and northwards to southern Bolivia during the late Middle Pleistocene and Late Pleistocene. Various other species belonging to the subgenus Pseudomegatherium ranging in size comparable to considerably smaller than M. americanum are known from the Andean region.
Mylodon is an extinct genus of ground sloth belonging to the family Mylodontidae, known from southern South America. With a total length of 3 to 4 m and a body mass of 1-2 tonnes, it is one of the largest mylodontids.
Ground sloths are a diverse group of extinct sloths in the mammalian superorder Xenarthra. They varied widely in size with the largest, belonging to genera Lestodon, Eremotherium and Megatherium, being around the size of elephants. Ground sloths represent a paraphyletic group, as living tree sloths are thought to have evolved from ground sloth ancestors.
Megatheriidae is a family of extinct ground sloths that lived from approximately 23 mya—11,000 years ago.
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, however, one possible find dating to the Eocene, about 40 Ma ago, on Seymour Island in Antarctica. They first reached North America by island-hopping across the Central American Seaway, about 9 million years ago, prior to formation of the Isthmus of Panama about 2.7 million years ago. Some megalonychid lineages increased in size as time passed. The first species of these were small and may have been partly tree-dwelling, whereas the Pliocene species were already approximately half the size of the huge Late Pleistocene Megalonyx jeffersonii from the last ice age.
Glossotherium is an extinct genus of large mylodontid ground sloths of the subfamily Mylodontinae. It represents one of the best-known members of the family, along with Mylodon and Paramylodon. Reconstructed animals were between 3 and 4 metres long and possibly weighed up to 1,002.6–1,500 kg. The majority of finds of Glossotherium date from the Middle and Upper Pleistocene, around 300,000 to 10,000 years ago, with a few dating older, as far back Pliocene, about 3.3-3 million years ago. The range included large parts of South America, east of the Andes roughly from latitude 20 to 40 degrees south, leaving out the Amazon Basin in the north. In western South America, finds are also documented north of the equator. The animals largely inhabited the open landscapes of the Pampas and northern savanna regions.
Eremotherium is an extinct genus of giant ground sloth in the family Megatheriidae. Eremotherium lived in southern North America, Central America, and northern South America from the Pliocene, around 5.3 million years ago, to the end of the Late Pleistocene, around 10,000 years ago. Eremotherium was one of the largest ground sloths, with a body size comparable to elephants, weighing around 4–6.5 tonnes and measuring about 6 metres (20 ft) long, slightly larger than its close relative Megatherium.
Nothrotherium is an extinct genus of medium-sized ground sloth from South America. It differs from Nothrotheriops in smaller size and differences in skull and hind leg bones.
Paramylodon is an extinct genus of ground sloth of the family Mylodontidae endemic to North America during the Pliocene through Pleistocene epochs, living from around ~4.9 Mya–12,000 years ago.
Catonyx is an extinct genus of ground sloth of the family Scelidotheriidae, endemic to South America during the Pliocene and Pleistocene epochs. It lived from 2.5 Ma to about 10,000 years ago, existing for approximately 2.49 million years. The most recent date obtained is about 9600 B.P.
Harrington's mountain goat was a species of caprine that resided in the Southwest of North America during the Pleistocene epoch. A relative of the modern mountain goat, which is the only existing species in the genus Oreamnos, O. harringtoni became extinct around 11,000 B.C.
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.
Nothrotheriidae is a family of extinct ground sloths that lived from approximately 17.5 mya—10,000 years ago, existing for approximately 17.49 million years. Previously placed within the tribe Nothrotheriini or subfamily Nothrotheriinae within Megatheriidae, they are now usually placed in their own family, Nothrotheriidae. Nothrotheriids appeared in the Burdigalian, some 19.8 million years ago, in South America. The group includes the comparatively slightly built Nothrotheriops, which reached a length of about 2.75 metres (9.0 ft). While nothrotheriids were small compared to some of their megatheriid relatives, their claws provided an effective defense against predators, like those of larger anteaters today.
Australonyx is an extinct genus of ground sloths, endemic to South America during the Late Pleistocene. It was found in Brazil.
Valgipes is an extinct genus of scelidotheriid ground sloth, endemic to intertropical Brazil and Uruguay during the Late Pleistocene. Thought to have been a forest-dwelling browser, Valgipes is a monotypic genus with a complex and long taxonomic history, and is a close relative of Catonyx and Proscelidodon.
Megatheriinae is a subfamily of the Megatheriidae, an extinct family of ground sloths that lived from the Middle Miocene to the Early Holocene.
Megathericulus is an extinct genus of ground sloths in the Megatheriidae family. It lived during the Middle Miocene, 11-16 Ma in what is now South America. Fossils have been found principally in Argentina, Bolivia, and Peru. It is a smaller representative of the megatheres. Despite being one of the earliest-known members of the family, its dentition structure is associated with homodont teeth belonging to the more modern line of evolution. The genus was scientifically named in 1904. Only one species is currently recognized, Megathericulus patagonicus.
Proeremotherium is an extinct genus of megatheriine ground sloths in the family Megatheriidae. It lived during the Late Miocene and Early Pliocene of what is now Venezuela. So far, two largely complete skulls have been recovered in the Falcón Basin in Venezuela. The finds identify the animals as medium-sized representatives of the Megatheriidae. In the cranial anatomy, Proeremotherium resembles the later and giant Eremotherium. It is therefore assumed that the two ground sloths are directly related to each other.
Lakukullus is an extinct genus of nothrotheriid ground sloths that lived during the Middle Miocene around 13.8 to 11.8 million years ago of what is now Bolivia.
Mesopotamocnus is an extinct genus of megalonychid ground sloth that lived during the Late Miocene in what is now Argentina. Fossils have been found in the Ituzaingó Formation of Argentina.