discovered in 1982 gave rise to speculation that this ancestor could be closer to the non-ruminants than the ruminants. Andromeryx is another prominent prehistoric ruminant, but appears to be closer to the tragulids. Oligocene The formation of the Himalayas and the Alps brought about significant geographic changes. This was the chief reason behind the extensive diversification of deer-like forms and the emergence of cervids from the Oligocene to the early Pliocene. The latter half of the Oligocene (28–34 Mya) saw the appearance of the European Eumeryx and the North American Leptomeryx. The latter resembled modern-day bovids and cervids in dental morphology (for instance, it had brachyodont molars), while the former was more advanced. Other deer-like forms included the North American Blastomeryx and the European Dremotherium; these sabre-toothed animals are believed to have been the direct ancestors of all modern antlered deer, though they themselves lacked antlers. Another contemporaneous form was the four-horned protoceratid Protoceras, that was replaced by Syndyoceras in the Miocene; these animals were unique in having a horn on the nose. Late Eocene fossils dated approximately 35 million years ago, which were found in North America, show that Syndyoceras had bony skull outgrowths that resembled non-deciduous antlers. Miocene Fossil evidence suggests that the earliest members of the superfamily Cervoidea appeared in Eurasia in the Miocene. Dicrocerus, Euprox and Heteroprox were probably the first antlered cervids. Dicrocerus featured single-forked antlers that were shed regularly. Stephanocemas had more developed and diffuse ("crowned") antlers. Procervulus (Palaeomerycidae) also possessed antlers that were not shed. Contemporary forms such as the merycodontines eventually gave rise to the modern pronghorn. The Cervinae emerged as the first group of extant cervids around 7–9 Mya, during the late Miocene in central Asia. The tribe Muntiacini made its appearance as † Muntiacus leilaoensis around 7–8 Mya; The early muntjacs varied in size–as small as hares or as large as fallow deer. They had tusks for fighting and antlers for defence. Capreolinae followed soon after; Alceini appeared 6.4–8.4 Mya. Around this period, the Tethys Ocean disappeared to give way to vast stretches of grassland; these provided the deer with abundant protein-rich vegetation that led to the development of ornamental antlers and allowed populations to flourish and colonise areas. As antlers had become pronounced, the canines were either lost or became poorly represented (as in elk), probably because diet was no longer browse-dominated and antlers were better display organs. In