Data from: Phylogeny, macroevolutionary trends and historical biogeography of sloths: insights from a Bayesian morphological clock analysis

Sloths, like other xenarthrans, are an extremely interesting group of
mammals that, after a long history of evolution and diversification in
South America, became established on islands in the Caribbean and later
reached North America during the Great American Biotic Interchange. In all
three regions they were part of the impressive Pleistocene megafauna. Most
taxa became extinct and only two small, distantly related tree-dwelling
genera survived. Here we incorporate several recently described genera of
sloths into an assembled morphological data supermatrix and apply Bayesian
inference, using phylogenetic and morphological clock methods, to 64 sloth
genera. Thus, we investigate the evolution of the group in terms of the
timing of divergence of different lineages and their diversity,
morphological disparity and biogeographical history. The phylogeny
obtained supports the existence of the commonly recognized clades for the
group. Our results provide divergence time estimates for the major clades
within Folivora that could not be dated with molecular methods. Lineage
diversity shows an early increase, reaching a peak in the Early Miocene
followed by a major drop at the end of the Santacrucian (Early Miocene). A
second peak in the Late Miocene was also followed by a major drop at the
end of the Huayquerian (Late Miocene). Both events show differential
impact at the family level. After that, a slight Plio-Pleistocene decline
was observed before the marked drop with the extinction at the end of the
Pleistocene. Phenotypic evolutionary rates were high during the early
history of the clade, mainly associated with Mylodontidae, but rapidly
decreased to lower values around 25 Ma, whereas Megalonychidae have lower
values at the beginning followed by a steady increase, peaking during the
Late Miocene and the Pliocene. Morphological disparity showed a similar
trend, with an early increase, followed by a slowly increasing phase
through the Late Oligocene and Early Miocene, and ending with another
increase beginning at the middle of the Miocene. Biogeographic analysis
showed southern South America as the most probable area of origin of the
clade and the main region in which the early diversification events took
place. Both Megatheriinae and Nothrotheriinae basal nodes were strongly
correlated with Andean uplift events, whereas the early history of
Mylodontidae is closely associated with southern South America and also
shows an early occupation of the northern regions. Within Megalonychidae,
our results show Choloepus as a descendant of an island dispersing
ancestor and a probable re-ingression to South America by a clade that
originated in Central or North America.