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

 Suidae
 Tayassuidae
 Entelodontidae †

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

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, a branch of the tylopoda, were often considered suines due to the popular, though inaccurate, description of them as "ruminating hogs". Oreodonts are not suines, but are closer related to camels. However, the predators of the oreodonts, the entelodonts of the extinct family entelodontidae, are most likely suines. The peccaries and entelodonts seem to be closer related to each other than either is to modern pigs. In addition, as mentioned below, the Hippopotamus and the related anthracotheres may also not be suines.

[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. doi:10.1073/pnas.0409518102. PMID 15677331. Retrieved on 2007-06-09. 
  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. PMID 9159931. 
  3. ^ Ursing,B.M. (1998). "Analyses of mitochondrial genomes strongly support a hippopotamus-whale clade". Proceedings of the Royal Society 265 (1412): 2251. doi:10.1098/rspb.1998.0567. 

[edit] External links