Suina

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Suina
Potamochoerus porcus
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Suborder: Suina
Gray, 1868
Families

 Suidae
 Tayassuidae
 Entelodontidae †
 ?Merycoidodontidae †

The suborder Suina (also known as Suiformes) contains perhaps the earliest and most archaic even-toed ungulates.

Contents

[edit] Classification

The suborder Suina includes the family Suidae (pigs, hogs) and the family Tayassuidae (peccaries). Some morphological studies also identified the family Hippopotamidae (hippopotami) among the Suina.

The oreodonts of the possibly-ancestral family Oreodontidae (best known for the genus Oreodon, a.k.a. Merycoidodon) are now extinct. Sometimes called "ruminating hogs," they were pig-like, cud-chewing plant-eaters with tusk-like canine teeth, short faces, and four-toed hooves. Although some scholars place them within the suborder Suina, others put them in their own suborder, named Oreodonta. The extinct Entelodonts are often regarded as members of the Suina as well.

These prehistoric artiodactyls were very common amid the dry grasslands of North and Central America throughout much of the Cenozoic era. Their teeth are often found as fossils amid the Oreodon beds in South Dakota, Nebraska, and Wyoming.

The primordial oreodonts appeared 48 million years ago (m.y.a.) during the Eocene epoch of the Paleogene period, but became extinct 4 m.y.a. during the early Pliocene epoch of the Neogene period. It is not known whether they were ancestral to the living genera of Suina.

[edit] Status of hippopotamidae

Hippopotamus were once thought to be part of the Suina, but a growing body of morphological and genetic evidence has suggested that they share a common ancestor not with Suina, but with Cetaceans—the Order which includes whales and dolphins. Whales and artiodactyls form a clade called Cetartiodactyla. [1]

The most recent research into the origins of hippopotamidae suggests that hippos and whales shared a common semi-aquatic ancestor that branched off from other Artiodactyls around 60 million years ago.[2] This hypothesized ancestor likely split into two branches around 54 million years ago.[3] One branch would evolve into cetaceans, possibly beginning with the proto-whale Pakicetus from 52 million years ago and other early whale ancestors, known as Archaeoceti, which eventually underwent aquatic adaptation into the almost completely aquatic cetaceans.[1]

[edit] Anatomy

The anatomy of the Suina is different compared to other even-toed ungulates. For example, they have maxillary teeth, which allow for proper chewing of food. In contrast, other even-toed ungulates such as goats and deer, have teeth only on the bottom. This doesn't let them chew very well, so they have to swallow it and regurgitate the food to allow rumination.

Most even-toed ungulates have a four-chambered stomach. In contrast, the Suina have a simple stomach that allows an omnivorous diet.

Boar skeleton
Boar skeleton

Most members of Suina have toes rather than hooves. While most artiodactyls have long slender legs, the Suina generally have short, stubby legs.

[edit] See also

[edit] References

  1. ^ a b Boisserie, Jean-Renaud; Fabrice Lihoreau and Michel Brunet (February 2005). "The position of Hippopotamidae within Cetartiodactyla". Proceedings of the National Academy of Sciences 102 (5): 1537-1541. 
  2. ^ Gatesy, J.. "More DNA support for a Cetacea/Hippopotamidae clade: the blood-clotting protein gene gamma-fibrinogen". Molecular Biology and Evolution 14: 537-543. 
  3. ^ Ursing,B.M. (1998). "Analyses of mitochondrial genomes strongly support a hippopotamus-whale clade". Proceedings of the Royal Society 265 (1412): 2251. 

[edit] External links