''Nothrotheriops'' is a genus of

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

ground sloth Ground sloths are a diverse group of extinct sloths in the mammalian superorder Xenarthra. The term is used to refer to all extinct sloths because of the large size of the earliest forms discovered, compared to existing tree sloths. The Caribb ...

found in

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...

, from what is now central Mexico to the southern United States.PaleoBiology Database: ''Nothrotheriops'', basic info
/ref> This genus of bear-sized

xenarthran Xenarthra (; from Ancient Greek ξένος, xénos, "foreign, alien" + ἄρθρον, árthron, "joint") is a major clade of placental mammals native to the Americas. There are 31 living species: the anteaters, tree sloths, and armadillos. Exti ...

was related to the much larger, and far more famous '' Megatherium'', although it has recently been placed in a different family,

Nothrotheriidae Nothrotheriidae is a family of extinct ground sloths that lived from approximately 17.5 mya—10,000 years ago, existing for approximately . Previously placed within the tribe Nothrotheriini or subfamily Nothrotheriinae within Megatheriidae, th ...

. The best known species, ''N. shastensis'', is also called the Shasta ground sloth.

Taxonomy, history, and etymology

''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 Shasta County (), officially the County of Shasta, is a county in the northern portion of the U.S. state of California. Its population is 182,155 as of the 2020 census, up from 177,223 from the 2010 census. The county seat is Redding. Shasta ...

, the fossils dating to the late Quaternary period.Sinclair, W. J. (1905). ''New mammalia from the Quaternary caves of California''. University of California Press.McDonald, H. G. (1995). Gravigrade xenarthrans from the early Pleistocene Leisey Shell Pit lA, Hillsborough County, Florida. ''Bulletin of the Florida Museum of Natural History'', ''37''(11), 245-373. These first fossils (

UCMP The University of California Museum of Paleontology (UCMP) is a paleontology museum located on the campus of the University of California, Berkeley. The museum is within the Valley Life Sciences Building (VLSB), designed by George W. Kelham and ...

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 The University of California Museum of Paleontology (UCMP) is a paleontology museum located on the campus of the University of California, Berkeley. The museum is within the Valley Life Sciences Building (VLSB), designed by George W. Kelham and ...

where they were described by paleontologist William Sinclair in 1904 as a new species of '' Nothrotherium, N. shastensis'' (species name meaning "from Shasta"). 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 Baylor University is a private Baptist Christian research university in Waco, Texas. Baylor was chartered in 1845 by the last Congress of the Republic of Texas. Baylor is the oldest continuously operating university in Texas and one of th ...

in Baylor, Texas. The skull had been collected in the

strata of

Wheeler County, Texas Wheeler County is a county located in the U.S. state of Texas. As of the 2020 census, its population was 4,990. Its county seat is Wheeler. The county was formed in 1876 and organized in 1879. It is named for Royall Tyler Wheeler, a chief j ...

and given to a clergyman who then gave it to university staff in 1901. 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 Robert Julien Hoffstetter (11 June 1908 in Fargniers – 29 December 1999 in Gennevilliers) was a French taxonomist and herpetologist who was influential in categorizing reptiles Reptiles, as most commonly defined are the animals in the clas ...

during a study of fossil sloths. ''N. texanus'' was recombined into the genus in 1995, and had many fossils referred to it from Florida, the easternmost occurrence of the genus. 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 La Brea Tar Pits is an active paleontological research site in urban Los Angeles. Hancock Park was formed around a group of tar pits where natural asphalt (also called asphaltum, bitumen, or pitch; ''brea'' in Spanish) has seeped up from the gr ...

. The most famous specimen was recovered from a

lava tube A lava tube, or pyroduct, is a natural conduit formed by flowing lava from a volcanic vent that moves beneath the hardened surface of a lava flow. If lava in the tube empties, it will leave a cave. Formation A lava tube is a type of lava ...

Aden Crater Aden Crater is a small shield volcano located in Doña Ana County, about southwest of Las Cruces, New Mexico. It is located in the northwest part of the Aden-Afton basalt field, which is part of the central area of the Potrillo volcanic field ...

in New Mexico and was found to still have hair and tendon preserved.Lull, S. 1929
A remarkable ground sloth
Memoirs of the Peabody Museum of Yale University, 3: 1-39. This nearly complete specimen is on display at the

Yale Yale University is a private research university in New Haven, Connecticut. Established in 1701 as the Collegiate School, it is the third-oldest institution of higher education in the United States and among the most prestigious in the wor ...

Peabody Museum of Natural History The Peabody Museum of Natural History at Yale University is among the oldest, largest, and most prolific university natural history museums in the world. It was founded by the philanthropist George Peabody in 1866 at the behest of his nephew Oth ...

New Haven, Connecticut New Haven is a city in the U.S. state of Connecticut. It is located on New Haven Harbor on the northern shore of Long Island Sound in New Haven County, Connecticut and is part of the New York City metropolitan area. With a population of 134 ...

. 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 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 ...

. The ancestors of ''Nothrotheriops'' migrated to North America from South America as part of the

Great American Interchange The Great American Biotic Interchange (commonly abbreviated as GABI), also known as the Great American Interchange and the Great American Faunal Interchange, was an important late Cenozoic paleozoogeographic biotic interchange event in which lan ...

during the

Blancan The Blancan North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 4,750,000 to 1,806,000 years BP, a period of .

Description

Although ''N. shastensis'' was one of the smallest

species, it still reached from snout to tail tip and weighed (one-quarter of a tonne) – much smaller than some of its contemporary species such as the ''

Eremotherium ''Eremotherium'' (from Greek for "steppe" or "desert beast": ἔρημος "steppe or desert" and θηρίον "beast") is an extinct genus of giant ground sloth, in the family Megatheriidae, the largest and most heavily built family of sloths. ' ...

'', which could easily weigh over two tonnes and be long.Lange, Ian M., ''Ice Age Mammals of North America: A Guide to the Big, the Hairy, and the Bizarre'', Mountain Press Publishing Company, 2002. Pg. 83, 85 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. ''

'').Barton Miles & Co., Prehistoric America. A journey through the Ice Age and beyond. BBC publishing, 2002. Pg 108-9.

Paleobiology

''Nothrotheriops'' behaved like all typical ground sloths of North and

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sou ...

, feeding on various plants like the desert globemallow,

cacti A cactus (, or less commonly, cactus) is a member of the plant family Cactaceae, a family comprising about 127 genera with some 1750 known species of the order Caryophyllales. The word ''cactus'' derives, through Latin, from the Ancient Gree ...

, and

yucca ''Yucca'' is a genus of perennial shrubs and trees in the family Asparagaceae, subfamily Agavoideae. Its 40–50 species are notable for their rosettes of evergreen, tough, sword-shaped leaves and large terminal panicles of white or whitis ...

. It was hunted by various local predators, like

dire wolves The dire wolf (''Aenocyon dirus'' ) is an extinct canine. It is one of the most famous prehistoric carnivores in North America, along with its extinct competitor ''Smilodon''. The dire wolf lived in the Americas and eastern Asia during the Lat ...

and ''

Smilodon ''Smilodon'' is a genus of the extinct machairodont subfamily of the felids. It is one of the most famous prehistoric mammals and the best known saber-toothed cat. Although commonly known as the saber-toothed tiger, it was not closely rela ...

'', 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 ''Walking with Beasts'', marketed as ''Walking with Prehistoric Beasts'' in North America, is a 2001 six-part nature documentary television miniseries created by Impossible Pictures and produced by the BBC Natural History Unit, the Discovery Chann ...

''. The same claws could also 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 Prehensility is the quality of an appendage or organ that has adapted for grasping or holding. The word is derived from the Latin term ''prehendere'', meaning "to grasp". The ability to grasp is likely derived from a number of different orig ...

tongue (like a

giraffe The giraffe is a large African hoofed mammal belonging to the genus ''Giraffa''. It is the tallest living terrestrial animal and the largest ruminant on Earth. Traditionally, giraffes were thought to be one species, '' Giraffa camelopardal ...

) to strip leaves off branches. The Shasta ground sloth is believed to have played an important role in the dispersal of ''

Yucca brevifolia ''Yucca brevifolia'' is a plant species belonging to the genus ''Yucca''. It is tree-like in habit, which is reflected in its common names: Joshua tree, yucca palm, tree yucca, and palm tree yucca. This monocotyledonous tree is native to the ar ...

'', 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.

Distribution and habitat

A fossil find had been described from as far north as the Canadian province of

Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest T ...

; however, this report is believed to have been mistaken. The genus lived primarily in the southwestern region of the U.S., from the states of

Texas Texas (, ; Spanish: ''Texas'', ''Tejas'') is a state in the South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2020, it is the second-largest U.S. state by ...

and

Oklahoma Oklahoma (; Choctaw: ; chr, ᎣᎧᎳᎰᎹ, ''Okalahoma'' ) is a state in the South Central region of the United States, bordered by Texas on the south and west, Kansas on the north, Missouri on the northeast, Arkansas on the east, New ...

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

; it has also been found in

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and ...

. The best known historical specimen was found in a

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe, New Mexico, Santa Fe , LargestCity = Albuquerque, New Mexico, Albuquerque , LargestMetro = Albuquerque metropolitan area, Tiguex , Offi ...

; it was found with hair and tendon still preserved. The Rampart Cave, located on the

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

side of the

Lake Mead National Recreation Area Lake Mead National Recreation Area is a U.S. national recreation area in southeastern Nevada and northwestern Arizona. Operated by the National Park Service, Lake Mead NRA follows the Colorado River corridor from the westernmost boundary of Gra ...

, has a plentiful amount of the sloth's hair and dung, both of which scientists used for

radiocarbon dating Radiocarbon dating (also referred to as carbon dating or carbon-14 dating) is a method for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of carbon. The method was de ...

to establish when it lived. 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 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. Becaus ...

). In addition to North America, fossils assigned to ''Nothrotheriops'' sp. have also been found as far south as

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the List of South American countries by area, second-largest ...

Santa Fe Province The Province of Santa Fe ( es, Provincia de Santa Fe, ) is a province of Argentina, located in the center-east of the country. Neighboring provinces are from the north clockwise Chaco (divided by the 28th parallel south), Corrientes, Entre R� ...

References

External links

{{Taxonbar, from=Q1088778 Prehistoric sloths Pleistocene xenarthrans Pleistocene mammals of North America Prehistoric placental genera Fossil taxa described in 1954