More on babirusas! Go here for part I.
While babirusas look pig-like and are classified as part of Suidae, they’re distinctive and unusual [image above from wikipedia]. Combining rather slender legs with a barrel-shaped body, they can exceed 1 m in length and have a shoulder height of 65-80 cm. Some individuals weigh as much as 100 kg. Babirusas are odd in having particularly remarkable canines (more about those soon), but less well known is that they differ from other pigs in several details of their anatomy, and in fact resemble peccaries and other artiodactyls in a few features. The tendons of their feet and some of their throat muscles are strikingly peccary-like, and they resemble ruminants (though only superficially) in a few details of their pectoral musculature, and in having a complex, multi-chambered stomach. Furthermore, the babirusa snout is not as specialised as that of other pigs.
In a curious parallel to this combination of anatomical features, the word babirusa combines babi, meaning pig, with rusa, meaning deer. It is supposed that Sulawesi people chose this name as the large canines of babirusas recall antlers, but it is also possible that the name reflects the amalgamation of deer-like slender legs and a multi-chambered stomach with the pig-like traits of the animal. Sulawesi people have always known of pigs other than babirusas, as Sulawesi is also home to the Sulawesi warty pig Sus celebensis*. Incidentally, you may recognise Rusa as the old generic name for the Sambar Cervus unicolor and other deer of Indonesia, the Philippines and adjacent islands [Sambar shown here, from wikipedia]. The Sunda sambar or Timor deer C. timorensis occurs on Sulawesi, but was probably introduced there from Java or Bali.
* A large extinct Pleistocene suid, Celebochoerus heekereni, was also endemic to Sulawesi, but (so far as we know) was not related to either babirusas or Sus celebensis.
In view of the divergent anatomy of babirusas, most artiodactyl specialists agree that they represent an ancient lineage, Babyrousinae, which branched off from the rest of Suidae early in its evolution (Thenius 1970). This is supported by chromosome data, as several autosomes present in babirusas have no equivalent in other suids. Unfortunately babirusa fossils only go back as far as the Pleistocene, but in theory we should expect to find babyrousines going back to the Oligocene [UPDATE: molecular data suggests Miocene - see comments below]. Is it possible that babirusas aren’t part of Suidae? Such a view was favoured by Deninger (1909) who argued that babirusas descended from anthracotheres like Merycopotamus. Anthracotheres, a widespread extinct group that appeared in the Eocene and survived into the Pleistocene in eastern Asia, are probably ancestral to hippos (and thus perhaps not close to suids at all), and while Deninger’s idea has been mostly dismissed it was viewed favourably by Groves (1981). He thought it at least possible that babirusas might really be extant anthracotheres, which is a pretty radical thought. For the record, no, this has not been accepted and babirusas are universally regarded as suids.
Despite the ancient divergence of babyrousines from other suids, a male babirusa hybridised with a female domestic pig at Copenhagen Zoo in 2006. Of the five resulting piglets, one died but the others survived. As you can see from the photo here, they look surprisingly normal. While the successful mating has surprised some biologists, we should remember that successful hybridisation can occur between species that are only distantly related, so it actually doesn’t mean much.
For previous articles on babirusas see…
For other Tet Zoo articles on artiodactyls see…
- McGowan’s mystery bovid
- The legend of Hogzilla
- Welcome…. to the world of sheep
- Return…. to the world of sheep
- Tet Zoo picture of the day # 23 [on entelodonts]
- Deer oh deer, this joke gets worse every time I use it
- Duiker, rhymes with biker
- Sable antelopes and the miseducation of youth
- Giant killer pigs from hell
- The plasticity of deer
- Over 400 new mammal species have been named since 1993
- Great Asian cattle
- Stuffed megamammal week, day 1: Khama
- Stuffed megamammal week, day 2: Eland
- Stuffed megamammal week, day 3: Okapi
- Death by lightning for giraffes, elephants, sheep and cows
- Dromomerycids: discuss
Refs – -
Deninger, K. 1909. Über Babirusa. Ber. Naturf. Ges. Freiburg 17, 179-200.
Groves, C. P. 1981. Ancestors for the Pigs: Taxonomy and Phylogeny of the Genus Sus. Technical Bulletin 3, Department of Prehistory, Research School Pacific Studies, Australian National University.
Thenius, E. 1970. Zur Evolution und Verbreitungsgeschicht der Suidae (Artiodactyla, Mammalia). Zeitschrift für Säugetierkunde 35, 321-342.