Bolivartherium

''Bolivartherium'' is an extinct genus of mylodontine mylodontid sloth that lived during the Late Miocene and Late Pliocene in what is now Venezuela. Fossils have been found in the Codore and Urumaco Formations of Venezuela.

Etymology

The generic name, ''Bolivartherium'', is named in honour of Libertador Simón Bolívar, 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) of Argentina. 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'', ''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. 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. 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, manatees, 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 and Glyptodontinae 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, '' Urumaquia'' and '' Proeremotherium'' as representatives of the large family Megatheriidae and '' Magdalenabradys'', ''Pseudoprepotherium'', '' Eionaletherium'' and ''Urumacotherium'' 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