Another Twist Decoding the Patterns of Evolution of the South American Extinct Mammalian Predators (Sparassodonta, Metatheria)

Abstract

The Sparassodonta are metatherian predators that lived in South America during most of the Cenozoic, becoming extinct in the Pliocene (ca. 3 Ma). Previous studies have explored the evolutionary patterns of sparassodonts by analyzing their fossil record. In this paper, we further study their evolution by combining information from the fossil record and phylogenetic relationships using different tree-time calibration methods. In addition, we explore the impact of different external and biological factors. The diversity of the clade exhibits a quadratic pattern, with an ascending phase until ca. 45 Ma, a relatively stable phase until ca.17 Ma, and finally, a descending phase that ends with its extinction. The factors that probably influenced the most on their diversity loss and extinction are the continuous increase in the altitude of different Andean ranges, the establishment of the Icehouse conditions worldwide, and the changes in the diversity of potential prey. Other clades of predatory mammals (competitors) probably did not influence the decline of the diversity of Sparassodonta recorded since ca. 17 Ma.