Baraguatherium is an extinct genus of ground sloths of the family Mylodontidae that lived during the Early Miocene of what is now Venezuela. It dates to the Early Miocene, around 20.44 to 15.97 million years ago and represents the oldest representative of its family in the northern part of South America to date. The structure of the teeth suggests that the genus represents a rather basal form within the Mylodontidae. Unlike other mylodonts, which tended to prefer open grasslands, Baraguatherium lived in a riverine, coastal tropical rainforest.
Discovery and naming
The remains of Baraguatherium known to date are from the Castillo Formation, which is exposed in the Falcón Basin in northwestern Venezuela. The Falcón Basin is located in the boundary of the Caribbean to the South American Plate. An almost complete depositional sequence has been preserved here, ranging from the Eocene to the Pliocene, some of which is very rich in fossils. The most important and best known finds to date are from the Urumaco sequence of the Middle and Upper Miocene. The Castillo Formation is stratigraphy older and covers the northwestern to southwestern margin of the Falcón Basin in a semicircular pattern. It was first studied and named in the 1960s. Among the most important outcrops is that of Cerro la Cruz near the town of La Mesa about 20km north of Carora in the Venezuelan state of Lara. It is located on the southern flank of the Serranía La Baragua and consists of a Sedimentary sequence at least 360m high on an area of about 2km². The sequence is composed of various layers of clay/siltstones, in which individual layers of limestone and sandstone are interbedded, in addition to which limonites and conglomerates occur locally. Altogether, four units (A to D from bottom to top) can be distinguished. Especially the three lower units contain abundant fossil material, which increases again strongly in the sections B and C. The fossil abundance was first noted in the transition from the 20th to the 21st century. Overall, marine life predominates in the fossil record, which includes crustaceans, mollusks, fish, turtles, manatees, and whales. Among these, some forms, such as the genus Portunus, which belongs to the decapods, suggest nearshore waters. Moreover, freshwater forms such as the Black pacu or the genus Mylossoma occur as representatives of fishes, as well as members of the Snake-necked Turtles. In the middle section of Unit C, remains of terrestrial vertebrates were also recovered. Prominent among these would be some members of the South American ungulates and the xenarthrans, including the remains of Baraguatherium. In this area, informally called Valle de los vertebrados (the valley of vertebrates), numerous bioturbations can be traced in the form of trace fossils, such as Gyrolithes, a possibly crustacean-like creature that dug corkscrew-like passage structures in the coastal soil. Based on the geological and paleontological evidence, a former mangrove-covered shallow coastal landscape can be assumed, which probably existed only for a short time. Dating using strontium isotopes gave the Castillo Formation an age of 19.27 to 17.21 million years, corresponding to the Lower Miocene, with the section that includes the terrestrial vertebrates likely younger than 18.27 million years. The isolated molars of Baraguatherium were presented in a scientific paper as early as 2004, but their exact taxonomic assignment, however, was uncertain. In another publication from 2014, the authors referred the mandible to the more basal ground sloth family Orophodontidae.
The genus name Baraguatherium is composed of the name Baragua for Serranía La Baragua (also Sierra de La Baragua), a mountain range in northern Venezuela, on the southern flank of which the Cerro la Cruz locality is located, and the Greek word θηρίον (thērion) for "beast". The only species known to date is Baraguatherium takumara. The species epithet refers to the word takumará of the Ayamanes Indio group, in whose language means "sloth".