Hipparionini is a tribe of three-toed horses in the subfamily Equinae. They had body forms similar to modern equines, with high-crowned teeth. They first appeared in North America during the Early Miocene around 17 million years ago, before migrating into the Old World around 11.4-11.0 million years ago. The youngest species date to the Early Pleistocene, becoming extinct following the arrival of modern equines of the genus Equus to the Old World.
Description
Hipparionines varied widely in size, with the smallest species like
Hipparion periafricanum having a body mass of only , considerably smaller than living equines,
while the largest species had body masses over .
Evolutionary history
In North America, hipparionins were equally diverse to
Equini during the
Middle Miocene but overtook them in
species richness during the
Late Miocene and
Zanclean. At the end of the
Hemphillian, hipparionins severely declined in diversity.
Ecology
In the Old World hipparionins were initially browsers and mixed feeders (both browsing and grazing), over time there was increasing proportion of pure grazers, though the groups ecology remained diverse, with mixed feeding being the dominant ecology during the
Pliocene.
Hipparionins in the western Mediterranean during the
Vallesian and
Turolian exhibited noticeable niche partitioning, with smaller forms being mixed feeders while larger species had more grazing diets. In contrast, contemporaneous eastern Mediterranean hipparionins did not exhibit such niche partitioning.
Taxonomy
North American genera:
Old World genera: (widely thought to descend from Cormohipparion)