''Aymaratherium'' is an extinct genus of nothrotheriid ground sloths that lived during the Late Miocene and Early Pliocene of

Bolivia Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in central South America. The country features diverse geography, including vast Amazonian plains, tropical lowlands, mountains, the Gran Chaco Province, w ...

. Fossils of ''Aymaratherium'' have been found in the Pomata Ayte locality of the Umala Formation.

Etymology

The genus name, ''Aymaratherium'', is derived from the Aymara, a native ethnic group and language from the

Andes The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the List of longest mountain chains on Earth, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range ...

, and ''therion'', meaning "beast". The specific name honors Jean Joinville Vacher, for his friendship and constant support for palaeontological investigations over the years.

Discovery

''Aymaratherium'' was first described in 2016 on the basis of a nearly complete right

dentary In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone ...

(specimen

MNHN The French National Museum of Natural History ( ; abbr. MNHN) is the national natural history museum of France and a of higher education part of Sorbonne University. The main museum, with four galleries, is located in Paris, France, within the ...

-Bol-V 008954), which was made of the holotype. In addition, three complete humeri (MNHN-Bol-V 003789, 012874 and 012875), a right

astragalus Astragalus may refer to: * ''Astragalus'' (plant), a large genus of herbs and small shrubs *Astragalus (bone) The talus (; Latin for ankle or ankle bone; : tali), talus bone, astragalus (), or ankle bone is one of the group of foot bones known ...

(MNHN-Bol-V 012983), and a complete right

calcaneus In humans and many other primates, the calcaneus (; from the Latin ''calcaneus'' or ''calcaneum'', meaning heel; : calcanei or calcanea) or heel bone is a bone of the Tarsus (skeleton), tarsus of the foot which constitutes the heel. In some other ...

(MNHN-Bol-V 003307) have also been assigned to the genus. The locality of the holotype was recovered from the Pomata-Ayte locality, in the Umala Formation, which is considered to be Early Pliocene in age, and is situated at the

Oruro Department Oruro (; Quechua: ''Uru Uru''; Aymara: ''Ururu'') is a department of Bolivia, with an area of . Its capital is the city of Oruro. According to the 2012 census, the Oruro department had a population of 494,178. Provinces of Oruro The depar ...

in Carangas Province near the city of the same name. Other vertebrate fauna found at the locality include the macraucheniid litoptern ''Macrauchenia'' sp''.'', the toxodontid notoungulate '' Posnanskytherium,'' several xenarthrans such as the sloths '' Simomylodon uccasamamensis'' '' Megatherium altiplanicum'', and the pampatheriid cingulate '' Plaina''.

Description

''Aymaratherium'' is a small to medium-sized nothrotheriid that was of similar size to '' Nothrotherium'' and ''

Thalassocnus ''Thalassocnus'' is an extinct genus of semiaquatic ground sloths from the Miocene and Pliocene of the Pacific South American coast. It is monotypic within the subfamily Thalassocninae. The five species—''T. antiquus'', ''T. natans'', ''T. lit ...

''. According to Pujos ''et al.'' (2016), ''Aymaratherium'' was diagnosed under the autapomorphies; the presence of lower dentition consisting of a single small caniniform and three large molariform teeth, the absence of a diastema between c1 and m1, a very high hypsodonty index, which is also seen in ''

Megatherium ''Megatherium'' ( ; from Greek () 'great' + () 'beast') 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 spe ...

'' and ''

Megalonyx ''Megalonyx'' (Greek, "great-claw") is an extinct genus of ground sloths of the family Megalonychidae, native to North America. It evolved during the Pliocene Epoch and became extinct at the end of the Late Pleistocene, living from ~5 million ...

,'' and a deep buccinator fossa and extremely thin dorsal margin of the spout. The molariform teeth of the type are mesially convex and the most mesial tooth closely approaches the dorsolateral margin of the mandible meaning that the individual was an adult or subadult at the time of its death.

Classification

The 2016 study that described ''Aymaratherium'' recovers it as a derived nothrotheriid, within the subfamily Nothrotheriinae, as the sister taxon to the tribe Nothrotheriini. Below is a parsimony tree establishing the relationships between the genera of the Nothrotheriidae, as proposed by Pujos ''et al'', 2016.

References

{{Taxonbar, from=Q112576771 Prehistoric sloths Prehistoric placental genera Miocene xenarthrans Pliocene xenarthrans Miocene mammals of South America Pliocene mammals of South America Neogene Bolivia Fossils of Bolivia Huayquerian Montehermosan Fossil taxa described in 2016