Taxonomy of wild pigs, peccaries and hippos

The Order Artiodactyla includes four suborders: Tylopoda (camels and llamas), Suoidea (also known as Suina or Suiformes), Whippomorpha (hippos and cetaceans) and Ruminantia (ruminants). While Tylopoda are a sister-group to the rest, and Suoidea are a sister-group to Whippomorpha and Ruminantia, the splits seem to have happened very rapidly in evolutionary time, and there would be little point in recognizing them as separate taxonomic ranks. Others have named the joint group as Cetartiodactyla (Cetacea and Artiodactyla) but this is considered to be taxonomically incorrect (see Asher & Helgen 2010) since Whippomorpha form a monophyletic clade deeply nested within the phylogeny of Artiodactyla.

As little as 20 years ago, the prevailing taxonomic arrangement was very different. The Cetacea (whales, dolphins and porpoises) were regarded as a separate order, and within the restricted Artiodactyla the major split was between Suiformes (pigs, peccaries and hippos) and Ruminantia, the latter incorporating the Tylopoda. Molecular data accumulated since then have without exception united the hippos and Cetacea into a monophyletic group, as a sister-group to the ruminants, while the Tylopoda, not the pigs and peccaries, are now seen as a sister-group to the rest of the Artiodactyla. Such conditions as stomach complexity, metapodial fusion and dental reduction are now seen as having arisen independently in camelids and ruminants.

Due to the former inclusion of hippos in th suborder Suiformes the newsletter Suiform Soundings and this websites also comprises informations about hippos.

Text adapted from: Gongora, J., Groves, C. and E. Meijaard 2017. Evolutionary Relationships and Taxonomy of Suidae and Tayassuidae. In: M. Meletti and E. Meijaard, editors. Ecology, Conservation and Management of Wild Pigs and Peccaries. Cambridge, UK.