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''Bolivartherium'' is an extinct genus of mylodontine mylodontid sloth that lived during the Late Miocene and Late Pliocene in what is now
Venezuela Venezuela, officially the Bolivarian Republic of Venezuela, is a country on the northern coast of South America, consisting of a continental landmass and many Federal Dependencies of Venezuela, islands and islets in the Caribbean Sea. It com ...
. Fossils have been found in the Codore and
Urumaco Formation The Urumaco Formation is a formation in Venezuela that includes deposits from the Late Miocene. It is the site of several "giant forms": the turtles, crocodiles, sloths and rodents of Urumaco are among the largest of their groups. Location The ...
s of Venezuela.


Etymology

The generic name, ''Bolivartherium'', is named in honour of Libertador
Simón Bolívar Simón José Antonio de la Santísima Trinidad Bolívar y Palacios (24July 178317December 1830) was a Venezuelan statesman and military officer who led what are currently the countries of Colombia, Venezuela, Ecuador, Peru, Panama, and Bol ...
, a Venezuelan military and political leader. The specific name is derived from the Urumaco Formation in which it was found in. A second species, ''B. codorensis'', was named in 2006 after the Codore Formation in which it was found in.


Description

''Bolivartherium'' is a medium-sized mylodontine that was smaller than the quaternary species of '' Lestodon''. It can be distinguished from the latter in having a lower rostrum and the upper caniform which is more curved than in ''Lestodon'', much like ''Lestodon'' sp. from the Monte Hermoso Formation (
Montehermosan The Montehermosan age is a period of geologic time (6.8–4.0 Mya (unit), Ma) within the Miocene and Pliocene epochs of the Neogene used more specifically with South American Land Mammal Ages. It follows the Huayquerian and precedes the Chapadmalal ...
) of
Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...
. The diastema in front of the molariforms is elevated with respect to the occlusal plane which is an apomorphic character with respect to other mylodontines, consequently, the alveolar margin of the caniniforms is dorsal to the molariforms, like in ''Lestodon'' sp. in Argentina, in contrast to the Quaternary species of ''Lestodon''.


Taxonomy

''Bolivartherium urumaquensis'' was originally assigned to the genus ''Lestodon'' by Omar Linares in 2004. However, it was subsequently found to be a distinct genus two years later in 2006. ''Bolivartherium'' is considered to be a derived mylodontid, closely related to ''
Lestobradys ''Lestobradys'' is an extinct genus of ground sloth (family Mylodontidae), which existed in Uruguay during the Late Miocene period; Huayquerian in the South American land mammal age (SALMA). The type species is ''L. sprechmanni'', found in the C ...
'', ''Lestodon'', '' Sphenotherus'', and '' Thinobadistes''. Below is a phylogenetic tree of the Mylodontidae, based on the work of Varela ''et al''. 2018, showing the position of ''Bolivartherium''. The following cladogram of the Mylodontidae is based on Boscaini ''et al''. 2019, showing the position of ''Bolivartherium''.


Paleoecology

The most extensive fossil material to date belongs to the Urumaco sequence, a complex depositional unit that is predominantly exposed in the approximately 36,000 km² large Falcón Basin in the Venezuelan state of
Falcón Falcón State (, ) is one of the 23 States of Venezuela, states of Venezuela. The state capital is Coro, Venezuela, Coro. The state was named after Juan Crisóstomo Falcón. History Early history Present day Falcón State was first explored ...
. It is composed of the lithostratigraphic units of the Urumaco and Codore Formations, with remains of ''Bolivartherium'' being limited to the two lower and first-mentioned sequences. The Urumaco sequence covers the period from the Middle Miocene to the
Early Pliocene Early may refer to: Places in the United States * Early, Iowa, a city * Early, Texas, a city * Early Branch, a stream in Missouri * Early County, Georgia * Fort Early, Georgia, an early 19th century fort Music * Early B, stage name of Jamaican d ...
. The main components are different layers of sand, clay and/silt and limestone in which individual coal seams are embedded, at least in the Urumaco Formation. The rock strata were formed in what was originally a coastal area under the influence of a river delta.Luis I. Quiroz und Carlos A. Jaramillo: ''Stratigraphy and sedimentary environments of Miocene shallow to marginal marine deposits in the Urumaco trough, Falcón Basin, Western Venezuela.'' In: Marcelo R. Sánchez-Villagra, Orangel A. Aguilera und Alfredo A. Carlini (Hrsg.): ''Urumaco and Venezuelan palaeontology, the fossil record of the northern Neotropics.'' Indiana University Press 2010, S. 153–172 From the entire Urumaco sequence, a large number of sites are documented, the exploration of which began as early as the 1950s. They are distributed over a good 60 different stratigraphic levels. The find material consists mainly of fish, especially sharks and rays. In addition, there are also reptiles such as turtles, crocodilians and isolated snakes, as well as mammals appearing with rodents, South American ungulates,
manatee Manatees (, family (biology), family Trichechidae, genus ''Trichechus'') are large, fully aquatic, mostly herbivory, herbivorous marine mammals sometimes known as sea cows. There are three accepted living species of Trichechidae, representing t ...
s, and minor jointed animals among others. The secondary articulated animals show a high diversity, which almost reaches that of the contemporary fauna of southern South America in the Pampas region or in Mesopotamia. Armadillos such as the
Pampatheriidae Pampatheriidae ("Pampas beasts") is an extinct family of large cingulates related to armadillos. They first appeared in South America during the mid-Miocene, and '' Holmesina'' and '' Pampatherium'' spread to North America during the Pleistocen ...
and
Glyptodont Glyptodonts are an extinct clade of large, heavily armoured armadillos, reaching up to in height, and maximum body masses of around 2 tonnes. They had short, deep skulls, a fused vertebral column, and a large bony carapace made up of hundreds o ...
inae as well as sloths have been found. Mainly in the late 20th and early 21st century, numerous new forms were described, such as '' Urumacocnus'' and '' Pattersonocnus'' from the family
Megalonychidae 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 datin ...
, '' Urumaquia'' and '' Proeremotherium'' as representatives of the large family
Megatheriidae Megatheriidae is a family of Extinction, extinct ground sloths that lived from approximately 23 Annum, mya—11,000 years ago. Megatheriids appeared during the Oligocene, Late Oligocene (Deseadan in the South American land mammal age, SALMA cl ...
and '' Magdalenabradys'', ''
Pseudoprepotherium ''Pseudoprepotherium'' is an extinct genus of sloths of the family Mylodontidae. It was widespread across northern South America during the Early to Late Miocene epoch around 21 to 5.3 million years ago. Fossils of the animal have been found in Br ...
'', '' Eionaletherium'' and ''
Urumacotherium ''Urumacotherium'' (meaning "Urumaco beast") is an extinct genus of ground sloths of the family Mylodontidae. It lived from the Middle Miocene to the Early Pliocene of what is now Brazil, Peru and Venezuela. Classification ''Urumacotherium'' is ...
'' from the lineage Mylodontidae and their immediate relatives. As a special circumstance of taphonomy, the frequent tradition of limb elements in sloths is to be evaluated, however, from ''Bolivartherium'' also documented remains of the skull.


References

{{Taxonbar, from=Q113903865 Prehistoric sloths Prehistoric placental genera Miocene xenarthrans Pliocene xenarthrans Miocene mammals of South America Pliocene mammals of South America Messinian first appearances Piacenzian extinctions Neogene Venezuela Fossils of Venezuela Chapadmalalan Montehermosan Huayquerian Fossil taxa described in 2006 Simón Bolívar