Rare Ichnofossil - Extinct Brontotheriid Fossil Tracks

Brontotheriid tracks (Ichnofossils)

Class Mammalia, Order Perissodactyla, Brontotheriidae indet.

Geological Time: Middle Eocene

Size (25.4 mm = 1 inch): Matrix 425mm X 450mm Four toed track 130mm X 150mm Three toed track 110mm X 120mm

Fossil Site: Green River Formation, Sevier County, Utah

Brontotheriid Fossil TracksThis rare ichnofossil plate was collected decades ago from a site that has been only recently rediscovered. Most probably, the area was a near-shore shelf along Uinta Lake that existed during the Eocene.

This plate contains the extremely rare tracks of a member of the Brontotheriidae family, extinct mammals belonging to the oOrder Perissodactyla which includes horses, rhinos, and tapirs. While brontotheres probably are most closely related to horses, they looked more like rhinoceroses. Brontotheres were browsers in warm temperate to subtropical environments and ranged from forest to open woodland. The group likely originated in North America during the early-middle Eocene and became extinct in North America by the end of the Eocene. They may have survived in Asia into the middle Oligocene.

While small three toed tracks described as extremely rare horse tracks have been found near Soldier Summit as reported in the The Journal of Paleontology (Novermber 1968), the Brontotheriidae tracks are not reported from Soldier Summit. You can clearly see the three toes of the hind foot, and the four toes of the front foot.

Also see: Green River Fossils

click fossil pictures to enlarge

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