Dinocerata

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Dinocerata Fossil range: Late Paleocene to (Late) Eocene
Illustration of Uintatherium 's head, a dinoceratan.
Scientific classification
Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Class: Mammalia Superorder: Laurasiatheria Order: Dinocerata
Families & Genera
See "Taxonomy"

Dinocerata, the so called "terrible horned" (dinocerata means terrible horn) mammals, are an extinct order of plant-eating, rhinoceros-like hoofed creatures famous for their paired horns and tusk-like canine teeth. The earliest dinoceratan, Prodinoceras, first appeared in Asia during the Paleocene, but nearly all later types are from North America (dinoceratans must have crossed the Bering land bridge, it may have been exposed during the Paleocene-Eocene times). They lived alongside with another large plant-eaters of the Eocene, the brontotheres. The most famous dinoceratan is Uintatherium.

[edit] Classification

How dinoceratans are related to other mammals is in dispute. They are probably part of the hoofed mammal (ungulate) group and have similarities with some South American hoofed mammals. Another idea is that dinoceratans are closely related to pantodonts and tillodonts. A more controversial view is that dinoceratans descend from the anagalids, a small group of rabbit-like mammals. But they may be related to an ungulatomorph group called zhelestidae. Many dinoceratans may be large, but they have one of the smallest brains of the mammal class (the smallest brains of the mammal class belongs to pantodonts), compare that to later ungulates (hoofed mammals) and other mammals.

Although dinoceratans are traditionaly placed in the superorder Ungulatomorpha, this clade is now considered to be paraphyletic. This is the result of recent genetic and molecular research, which are rewriting the story of mammalian classificaton. The members of the Ungulatomorpha are now placed in three very different lineages of placental mammals (Afrotheria, Laurasiatheria, Atlantogenata). In the case of the dinoceratans, it's now believed they are related to "true" Ungulates after all, so they should be considered members of the Laurasiatheria. They could be most closely related to the true Ungulate orders Perissodactyla and Artiodactyla. It is, however, entirely possible that one of the earlier evolutionairy views is true: that the dinoceratans are related to the pantodonts and tillodonts and should be treated among the Cimolesta. As it is impossible to extract genetic material from fossiles, the exact relationship of dinoceratans is likely to keep shifting in the nearby future.

[edit] Taxonomy and Phylogeny

Most experts place all of the known genera of Dinocerata within one family, Uintatheriidae, and split it into two subfamilies, Uintatheriinae and Gobiatheriinae. Some experts prefer to split Uintatheriidae into three families, with Gobiatherium in Gobiatheriidae, the other Eocene genera into Uintatheriidae proper, and place the Paleocene genera, Prodinoceras and Probathyopsis into the family "Prodinoceratidae."

• Laurasiatheria
  • Ungulatomorpha?
  • Order Dinocerata
    • Family Uintatheriidae
      • Subfamily Gobiatheriidae
        • Gobiatherium
      • Subfamily Uintatheriinae
        • Prodinoceras
        • Probathyopsis
        • Dinoceras
        • Bathyopsis
        • Uintatherium
        • Eobasileus or Uintacolotherium
        • Tetheopsis
        • Ditetradon
        • Jiaoluotherium