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 Camacho Formation of Uruguay.''Lestobradys''
at Fossilworks.org

Etymology

The genus name, ''Lestobradys'', is derived from ''lesto'', meaning "robber", which refers to the genus' morphological similarities to the Plio-Pleistocene ''Lestodon,'' while "''bradys''" means "slow" due to its common use in ground sloths. The specific name is after Uruguayan paleontologist and professor Peter Sprechmann.

History and taxonomy

''Lestobradys'' was first described in 2010 based on a fragmentary skull, nearly complete hemimandible, 2 complete dorsal vertebrae, another fragmentary dorsal, and 2 complete caudal vertebrae that were made the holotype and registered at the Coleccion de Paleontologia de Vertebrados de la Facultad de Ciencias under FCDPV 1826. A nearly complete mandible, FCDPV 462, was also referred as a paratype that was originally referred to ''Ranculcus.'' The holotype had been collected in Kiyu beach coastal platform, 1 kilometer east of San Gregorio creek in San Jose, Uruguay. The strata the holotype fossils were found in was from the San Pedro member of the Camacho Formation of the Huayquerian, late Miocene. Additionally, an astragalaus was also referred to ''Lestobradys sprechmanni'' that may be part of the holotype individual that had been found nearby.

Description

Due to the fragmentary nature of the fossils of ''Lestobradys'', much of the anatomy has to be inferred based on more complete relatives like ''Thinobadistes'' and ''Lestodon''. According to Rinderknecht ''et al'' (2010), ''Lestobradys'' was diagnosed under the autapomorphies; a combination of a first alveolus strongly projected toward the labial region that is separated from the rest of the alveoli of the dental series by a marked diastema, a subtriangular second alveolus, a subquadrangular third alveolus, and a bilobed last alveolus with a clearly defined isthmus separating both lobes. The caudal vertebrae of the type bear completely fused vertebral discs in the centra meaning that the individual was an adult or subadult at the time of its death. The astragalus' internal articular surface for the tibia forms a distinct elevated odontoid process, as a result of which the tibial surfaces of the astragalus overlap each other, forming a slightly acute angle. This condition is also seen in ''Lestodon,'' some mylodontids, and some megatheriids.

Classification

''Lestobradys'' was classified as a basal mylodontine by Rinderknecht ''et al'' on the basis of the dental anatomy in the labial portion of the mandible, noting that the morphology of the mandibles of ''Lestobradys'' is similar to that of ''Lestodon'' in bearing a prominent labial projection of the first tooth (caniniform) separated by a long diastema. However, the teeth of ''Lestodon'' are all rounded while the 2nd and 3rd teeth are prismatic in ''Lestobradys''. The long diastema is also similar to that in '' Ocnotherium'' but is much more pronounced and the taxa bearing this differentiates it from ''Pseudoprepotherium.''

In their phylogenetic analysis of Mylodontoidea, Boscaini ''et al'' (2019) recovered ''Lestobradys'' as the sister taxon to ''Sphenotherus zavaletianus'' and as a lestodontin instead of a basal mylodontid.

References

{{Taxonbar, from=Q6532022

Prehistoric sloths
Miocene mammals of South America
Montehermosan
Huayquerian
Chasicoan
Mayoan
Neogene Uruguay
Fossils of Uruguay
Fossil taxa described in 2010