Nothrotheriops

{{Automatic taxobox

| fossil_range = Pleistocene, {{fossil range|2.6|0.012}}

| image = Shasta ground sloth front.jpg

| image_caption = N. shastensis skeleton with preserved skin, Yale Peabody Museum

| image2 = Nothrotheriops shastensis.jpg

| image2_caption = Restoration of N. shastensis

| taxon = Nothrotheriops

| authority = Hoffstetter, 1954

| subdivision_ranks = Species

| subdivision =

†N. shastensis (Sinclair 1905)
†N. texanus (Hay 1916)

| type_species = †Nothrotheriops shastensis

| type_species_authority = Sinclair, 1905

}}

Nothrotheriops is a genus of Pleistocene ground sloths found in North America, from what is now central Mexico to the southern United States.[https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=43617 PaleoBiology Database: Nothrotheriops, basic info] This genus of bear-sized xenarthrans was related to the much larger, and far more famous Megatherium, although it has recently been placed in a different family, the Nothrotheriidae.{{cite journal

| last = Muizon

| first = C. de

|author2=McDonald, H. G. |author3=Salas, R. |author4=Urbina, M.

| title = The Youngest Species of the Aquatic Sloth Thalassocnus and a Reassessment of the Relationships of the Nothrothere Sloths (Mammalia: Xenarthra)

| journal = Journal of Vertebrate Paleontology

| volume = 24

| issue = 2

| pages = 387–397

| publisher = Society of Vertebrate Paleontology

|date=June 2004

| doi = 10.1671/2429a

| bibcode = 2004JVPal..24..387D

| s2cid = 83732878

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

Taxonomy, history, and etymology

File:Shasta ground sloth skull.jpg

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.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 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"). 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 Waco, 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.Hay, O. P. (1916). Descriptions of two extinct mammals of the Order Xenarthra from the Pleistocene of Texas (Vol. 51, No. 2147). US Government Printing Office. Many fossils were later referred to the two, but N. shastensis was not 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.Hoffstetter, R. (1954). Les gravigrades (Edentés Xénarthres) des cavernes de Lagoa Santa (Minas Gerais, Brésil). Annales des Sciences Natureles, Zoologie, 16, 741-764. 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. 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.Lull, S. 1929. [http://bhl-china.org/bhldatas/pdfs/r/remarkableground32lull.pdf A remarkable ground sloth] {{Webarchive|url=https://web.archive.org/web/20160203132546/http://bhl-china.org/bhldatas/pdfs/r/remarkableground32lull.pdf |date=2016-02-03 }}. Memoirs of the Peabody Museum of Yale University, 3: 1-39. This nearly complete specimen is on display at the Yale Peabody Museum of Natural History in New Haven, Connecticut. Numerous dung boli belonging to Nothrotheriops have also been found throughout the Southwestern United States and have provided an insight into the diet of these extinct animals.

File:Nothrotheriops texanus Holotype USNM8353.jpg

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 million years ago.

Description

Although N. shastensis was one of the smallest mainland ground sloth species, it still reached {{convert|2.75|m|ft|abbr=on}} from snout to tail tip and weighed {{convert|250|kg|lb|0|abbr=on}}{{Cite web |url=http://library.sandiegozoo.org/factsheets/_extinct/sloth_extinct/extinct_sloth.htm |title=Extinct Ground Sloth Fact Sheet |access-date=2016-10-29 |archive-url=https://web.archive.org/web/20150214074751/http://library.sandiegozoo.org/factsheets/_extinct/sloth_extinct/extinct_sloth.htm |archive-date=2015-02-14 |url-status=dead }} (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 {{convert|6|m|ft|abbr=on}} 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 hind legs and a powerful, muscular tail that it used to form a supporting tripod whenever it shifted from a quadrupedal to a bipedal stance (i.e. Eremotherium).Barton Miles & Co., Prehistoric America. A journey through the Ice Age and beyond. BBC publishing, 2002. Pg 108-9.

Paleobiology

File:Nothrotherium hair UCMP.JPG, Nevada]]

Image:Nothrotheriops.jpg

Nothrotheriops behaved like all typical ground sloths of North and South America, feeding on various plants, such as the desert globemallow, cacti, and yucca. It was hunted by various local predators, including dire wolves and Smilodon, from which the sloths may have defended themselves by standing upright on hind legs and tail, and swiping with their long fore claws, like their 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.

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. The lack of Shasta ground sloths helping to disperse the seeds to more favourable climates may be causing the tree populations to suffer.{{cite journal|last=Cole|first=Kenneth L.|author2=Kirsten Ironside |author3=Jon Eischeid |author4=Gregg Garfin |author5=Phillip B. Duffy |author6= Chris Toney |year=2011|title=Past and ongoing shifts in Joshua tree distribution support future modeled range contraction |journal=Ecological Applications|volume=21|issue=1|pages=137–149|url=http://www.fs.fed.us/rm/pubs_other/rmrs_2011_cole_k001.pdf|doi=10.1890/09-1800.1 |pmid=21516893|bibcode=2011EcoAp..21..137C }}{{cite web|url=https://www.npr.org/templates/story/story.php?storyId=17628032 |title=Outlook Bleak for Joshua Trees |publisher=Npr.org |date=2008-02-04 |access-date=2012-03-30}}

Distribution and habitat

File:Rampart Cave interior sloth dung.jpgized N. shastensis dung in Rampart Cave, Arizona (NPS, 1938)]]

A fossil find had been described from as far north as the Canadian province of Alberta, but this report is believed to have been mistaken.{{cite journal

| last =Akersten | first =W. A. |author2=McDonald, H. G.

| title = Nothrotheriops from the Pleistocene of Oklahoma and Paleogeography of the Genus

| journal = The Southwestern Naturalist

| volume = 36 | issue = 2 | pages = 178–185

| date = June 1991 | doi =10.2307/3671918 | jstor = 3671918 }} 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.

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. 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. 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).{{Cite book

| contribution = Sudden Deaths: The Chronology of Terminal Pleistocene Megafaunal Extinction

| title = American Megafaunal Extinctions at the End of the Pleistocene

| year = 2009 | pages = 21–37 | publisher = Springer

| doi = 10.1007/978-1-4020-8793-6_2 | isbn = 978-1-4020-8792-9

}} In addition to North America, fossils assigned to Nothrotheriops species have also been found as far south as Argentina's Santa Fe Province.{{Cite journal |last1=Brandoni |first1=Diego |last2=Vezzosi |first2=Raúl I. |date=2019 |title=Nothrotheriops sp. (Mammalia, Xenarthra) from the Late Pleistocene of Argentina: implications for the dispersion of ground sloths during the Great American Biotic Interchange |url=https://www.academia.edu/39238017 |journal=Boreas |volume=48 |issue=4 |pages=879 |doi=10.1111/bor.12401 |bibcode=2019Borea..48..879B |s2cid=181709381 |issn=0300-9483}}

== References ==

External links

[http://www.helsinki.fi/~mhaaramo/metazoa/deuterostoma/chordata/synapsida/eutheria/edentata/phyllophaga/megatheriidae.html Family tree of Megatheriidae]
[http://www.sdnhm.org/archive/exhibits/mystery/fg_giantsloth.html SDNHM Fossil Mysteries Field Guide, "Ground Sloths"]

Category:Prehistoric sloths

Category:Pleistocene xenarthrans

Category:Pleistocene mammals of North America

Category:Prehistoric placental genera

Category:Fossil taxa described in 1954