The family is represented in the Lower, or Wasatch, Eocene by Trigonolestes, in the Middle (Bridger) Eocene by Homacodon (Pantolestes), and in the Upper (Uinta) Eocene by Bunomeryx.
Middle Eocene (Bridger for mation).
The Bridger stage, when deposition was in progress in the -\Vind River basin, north of the mountain of that name, and in the basin of Green river.
The strange phenomena of this region were known to some of the Indians; they were discovered by John Colter, a member of the Lewis and Clark expedition, in 1807; the region was visited by James Bridger before 1840; an account of the geysers was published at Nauvoo, Illinois, in The Wasp, a Mormon paper, in 1842; Captain W.
A second group is typified by Palaeosyops, of the Bridger Eocene of North America; P. paludosus being an animal about the size of a tapir.