Abstract
Didelphidae is the largest New World radiation of marsupials, and is mostly represented by arboreal, small- to medium-sized taxa that inhabit tropical and/or subtropical forests. The group originated and remained isolated in South America for millions of years, until the formation of the Isthmus of Panama. In this study, we present the first reconstruction of the biogeographic history of Didelphidae including all major clades, based on parametric models and stratified analyses over time. We also compiled all the pre-Quaternary fossil records of the group, and contrasted these data to our biogeographic inferences, as well as to major environmental events that occurred in the South American Cenozoic. Our results indicate the relevance of Amazonia in the early diversification of Didelphidae, including the divergence of the major clades traditionally ranked as subfamilies and tribes. Cladogeneses in other areas started in the late Miocene, an interval of intense shifts, especially in the northern portion of Andes and Amazon Basin. Occupation of other areas continued through the Pliocene, but few were only colonized in Quaternary times. The comparison between the biogeographic inference and the fossil records highlights some further steps towards better understanding the spatiotemporal evolution of the clade. Finally, our results stress that the early history of didelphids is obscured by the lack of Paleogene fossils, which are still to be unearthed from low-latitude deposits of South America.
Highlights
The Metatheria clade corresponds to the extant marsupials plus all the extinct mammals more related to those than to the placentals
Considering the relevance of marsupials in the South American fauna, the objectives of this work are: (i) to estimate the area of origin and diversification of Didelphidae based on parametric models for ancestral area estimates; (ii) to compile the pre-Quaternary fossil record of the group; and (iii) to contrast these data to each other and to major biogeographic events that occurred in South America during the Cenozoic
The analysis of Mitchell et al (2014) indicated that, after a long gap since Didelphimorphia diverged from other marsupials, the first internal split of crown Didelphidae occurred in the late Eocene, and all major clades had diversified up to the middle Miocene
Summary
The Metatheria clade corresponds to the extant marsupials plus all the extinct mammals more related to those than to the placentals (see Goin et al 2016). Metatherians formed a diverse group in Laurasia during the Late Cretaceous, where they are abundantly found, especially in fossil assemblages of North America. There is a single living group of Metatheria, the Marsupialia, which is taxonomically and morphologically diverse in Australia, South America, and Central America (Goin et al 2016). The group probably reached South America following tectonic activities in the Caribbean plate that created a temporary bridge between South and North America during the Late Cretaceous (Campanian stage; Pascual 2006). Case et al (2005) considered that the most probable dispersal path was the Aves Ridge, a volcanic arc in the Caribbean Sea that began to dissipate in the Paleocene. Goin et al (2012) named this migration
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