A dwarf sabertooth cat (Felidae: Machairodontinae) from Shanxi, China, and the phylogeny of the sabertooth tribe Machairodontini

Abstract

The tribe Machairodontini is a major lineage of felid sabertooth cats that flourished in the late Cenozoic and included the top predators in the ecosystem of that time. As top predators members of the tribe had a profound influence on the paleoenvironment, yet the evolution and diversification of this tribe are unclear due to a lack of comprehensive revision and phylogenetic study. Here we describe a new dwarfed ecomorph of Machairodontini, Taowu liui gen. et sp. nov., from the Early Pleistocene of northern China, and carry out the best sampled phylogeny of the subfamily to date. Our analyses support that the African Mio-Pleistocene Lokotunjailurus represents an early divergent group, convergent with the Amphimachairodus-Homotheriina lineage in dental traits. The derived Pliocene to Pleistocene subtribe Homotheriina originated in Africa, from Adeilosmilus gen. nov. kabir or very a closely related taxon. Taowu liui gen. et sp. nov. belongs to a sister clade to Homotheriina. The Plio-Pleistocene Homotheriina of the New World belong to a monophyletic group in which Ischyrosmilus-Xenosmilus show a gradual adaptation to handling slow and powerful prey, whereas the true Homotherium only appeared after the Middle Pleistocene, in a separate intercontinental dispersal event.