Oreodont

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Oreodonts Fossil range: Middle Eocene to Pliocene[citation needed]
Reconstructions of various Miocene oreodonts, including Merycochoerus, Promerycochoerus, and Brachycrus
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Artiodactyla Suborder: Oreodonta Family: Merycoidodontidae
Subfamilies
Oreonetinae Leptaucheniinae Merycoidodontinae (Oreodontinae) Miniochoerinae Desmatochoerinae Promerycochoerinae Merychyinae Eporeodontinae Phenacocoelinae Ticholeptinae

Sometimes called a prehistoric "ruminating hog," (although they were neither Ruminants nor hogs), the typical oreodont ("Mountain teeth") was a sheep-sized (though some genera grew to the size of cattle), cud-chewing plant-eater with a short face, tusk-like canine teeth, heavy body, long tail, short feet, and four-toed hooves.

The animals would have looked rather sheep-like, but features of their teeth indicate that they were more closely related to camelids. They were most likely woodland and grassland browsers, and were widespread in North America during the Oligocene and Miocene. Later forms diversified to suit a range of different habitats. For example, Promerycochoerus had adaptations suggesting a semi-amphibious lifestyle, similar to that of modern hippos^[1].

Contents 1 Taxonomy 2 Natural history 3 Life and Lifestyle 4 Diversity 5 Classification 6 References

[edit] Taxonomy

Oreodonts belong to the family Merycoidodontidae (also known as Oreodontidae) which, along with Agriochoeridae, forms the now-extinct suborder Oreodonta. Oreodonts may have been distantly related to pigs, hogs, hippopotamuses, and the pig-like peccaries. Indeed, some scholars place Merycoidodontidae within the pig-related suborder Suina (a.k.a. Suiformes). Other scholars place oreodonts closer to camels in the suborder Tylopoda. Still other experts put the oreodonts together with the short-lived cainotheres in the taxonomic suborder Ancodonta comprising these two groups of extinct ancodonts. All scholars agree, however, that the oreodont was an early form of even-toed ungulate, belonging to the order Artiodactyla among the placental mammals. Some scholars groups the Agriochoeridae along with the Merycoidodontidae as Oreodonts.

Over 50 genera of Oreodonta have been described in the paleozoological literature. However, oreodonts are widely considered to be taxonomically oversplit,^[2][3] and many of these genera may prove to be synonymous. The last researchers to fully review oreodont taxonomy, C. Bertrand Schultz and Charles H. Falkenbach,^[4] have been criticized for erecting excessive numbers of genera, based in part on apparent anatomical differences between different specimens that were actually taphonomic deformations due to post-burial forces.^[2] Undeformed skulls would be placed in one genus, while skulls crushed from side to side would be placed in a second genus and skulls crushed from front to back would be placed in a third genus. Researchers are beginning to restudy oreodonts and synonymize many genera, but only a few groups have been reviewed.^[2][5][6]

By far the most well-known oreodont genus is Merycoidodon, formerly and popularly known as "Oreodon".

[edit] Natural history

This diverse group of stocky prehistoric mammals grazed amid the grasslands, prairies or savannas of North and Central America throughout much of the Cenozoic era. First appearing 48 million years ago (m.y.a.) during the warm Eocene epoch of the Paleogene period, the oreodonts dominated the American landscape 34 to 23 m.y.a. during the dry Oligocene epoch of the late Paleogene. But they mysteriously disappeared 4 m.y.a. during the colder Pliocene epoch of the late Neogene period^{[citation needed]}. Today, fossil jaws and teeth of the Oreodonta are commonly found amid the Oreodon beds of the White River badlands in South Dakota, Nebraska, and Wyoming. Many oreodont bones have also been reported at the John Day Fossil Beds National Monument in Oregon. Some oreodonts have been found at Agate Fossils Beds National Monument.

[edit] Life and Lifestyle

Most of this information is from the Tate Museum, one of the best museums with oreodont fossils. It mainly refers to the badlands Oligocene oreodonts, so the information may not be the most accurate for non Badlands fossils.

Dr. Kent Sundell theorizes that at least some species of oreodonts, due to their shorter legs compared to three-toed horses, running rhinos, and gazelles, and their large claws, dug burrows like the modern day prairie dog instead of fleeing from their enemies. Evidence seems to support this, for at the Tate Museum there is what appears to be a series of collapsed burrows with several baby and sub-adult Miniochoerus trapped inside.

Oreodonts could also fight back if need be. All species had claws instead of hooves, and some species such as Mesoreodon and Merycoidodon had some very nasty looking fang-like tusks. A potential predator, such as Archaeotherium or Hyaenodon, would be driven off by a powerful bite or a swipe of its claws.

It is presumed that the majority of oreodonts lived in herds, as suggested by the thousands of individuals in the various mass mortalities seen in the White River Badlands, "Oreodont Beds," or Chula Vista.

[edit] Diversity

Oreodonts underwent a huge diversification during the Oligocene and Miocene, adapting to a good number of ecological niches, including:

• Semi-aquatic- The hippo-like Promerycochoeus
• Trunked Browser- The tapir-like Brachycus
• Large Grazer- The cow-sized Eporeodon
• Medium Grazer- The goat-like Merycoidodon
• Small Desert Herbivore- The goat to cat-sized Sespia
• Medium Desert Herbivore- Mesoreodon and the ubiquitous Leptauchenia

[edit] Classification

The family Merycoidodontidae is divided up into ten subfamilies, with six genera not included in any subfamily (incertae sedis) because they are either regarded as basal oreodonts, or their status within the family remains uncertain.

• Family †Merycoidodontidae
  • subfamily incertae sedis
    • †Aclistomycter
    • †Limnenetes
    • †Metoreodon
    • †Pseudogenetochoerus
    • †Pseudoleptauchenia
    • †Superdesmatochoerus
  • Subfamily †Oreonetinae
    • †Bathygenys
    • †Megabathygenys
    • †Oreonetes
    • †Parabathygenys
  • Subfamily †Leptaucheniinae^[5]
    • Tribe †Leptaucheniini
      • †Leptauchenia (=Brachymeryx, Cyclopidius, Hadroleptauchenia, Pithecistes, Pseudocyclopidius)
    • Tribe †Sespiini
      • †Sespia (=Megasespia)
  • Subfamily †Merycoidodontinae (=Oreodontinae)^[2]
    • †Merycoidodon (=Blickohyus, Genetochoerus, Oreodon, Otionohyus, Paramerycoidodon, Prodesmatochoerus, Promesoreodon, Subdesmatochoerus)
    • †Mesoreodon
  • Subfamily †Miniochoerinae^[2]
    • †Miniochoerus (=Paraminiochoerus, Parastenopsochoerus, Platyochoerus, Pseudostenopsochoerus, Stenopsochoerus)
  • Subfamily †Desmatochoerinae
    • †Desmatochoerus
    • †Megoreodon
    • †Pseudodesmatochoerus
  • Subfamily †Promerycochoerinae
    • †Promesodreodon
    • †Promerycochoerus
    • †Merycoides
  • Subfamily †Merychyinae
    • †Oreodontoides
    • †Paroreodon (=Epigenetochoerus)
    • †Paramerychyus
    • †Merychyus
  • Subfamily †Eporeodontinae
    • †Dayohyus
    • †Eporeodon
  • Subfamily †Phenacocoelinae
    • †Phenacocoelus
    • †Submerycochoerus
    • †Pseudomesoreodon
    • †Hypsiops
  • Subfamily †Ticholeptinae
    • †Mediochoerus
    • †Ticholeptus (=Poatrephes)
    • †Ustatochoerus
  • Subfamily †Merycochoerinae
    • †Merycochoerus
    • †Brachycrus (=Pronomotherium)

[edit] References