A selection of extinct species of bovids, to scale.

Following on from the first post on bovids: www.deviantart.com/artbyjrc/ar…, this post will look at medium-sized species.

Modern bovids are split between nine subfamilies: bovines (cattle + spiral-horned antelope), antelopines (gazelles + dwarf antelope), cephalophines (duikers), reduncines (waterbuck + allies), aepycerotines (impala), caprines (sheep + goats), hippotragines (oryx + allies) and the alcelaphines (hartebeest). What is very obvious from this list is that the term 'antelope' refers to a variety of small, medium and large-bodied horned ungulates, and not one taxonomic unit. Consequently the explosion of small and medium-sized horned ungulates during the Miocene have caused confusion and species are often lumped into various groups until they can be re-examined.

* A case in point is Palaeoreas, a medium-sized antelope from Late Miocene, strikingly similar to the modern Indian blackbuck. Males had robust tightly twisted horns, while females lacked horns. A large ante-orbital depression is indicative of pre-orbital glands which produce secretions used to mark territories. All of these features are typical for many antelope species, but not necessarily seen in one group. Thus at this point, Palaeoreas is a probable antilopine, but sufficiently distinct.

* Likewise Oioceros was a contempory species which also shows some similarities to modern gazelles. However Oioceros and it's nearest relatives (such as Samotragus, Hispanodorcas and Paraoioceros) show a remarkable variety of horn shapes from short stabbing spikes to broad ramming horns. The later Gazellospira was a true antelopine and very similar to blackbuck apart from the widely diverging horns.

* Alcelaphines include the familiar and abundant wildebeest which live on open savannahs. Their heavy forequarters, Roman nose and shaggy manes give wildebeest a very different appearance to other antelope. A very close relative from the Pleistocene, Rusingoryx is notable for large nasal dome which was used for amplifying vocalizations. Many specimens have been found alongside human butchering tools.

* Also found in the Pleistocene was a medium-sized relative of the modern Indian nilgai, Duboisia. Unlike it's living relatives, this species was a browser of closed forests. Although forest living is unusual for bovids some modern species such as bongo and saola would be good analogues.

* Modern wild sheep are widespread but restricted to mountainous areas of Eastern Europe, Asia and Western North America. Until the discovery of Protovis, there was uncertainity as to the ancestral home of modern sheep. Living on the Tibetan plateau during the Pliocene, Protovis combines some basal features distinguishable from other known species.