middle to late Eocene, many different species existed. The smallest of these were the size of a mouse but others were much larger than any extant relatives. Titanohyrax could reach or even as much as over . Megalohyrax from the upper Eocene-lower Oligocene was as huge as tapir. During the Miocene, however, competition from the newly developed bovids, which were very efficient grazers and browsers, displaced the hyraxes into marginal niches. Nevertheless, the order remained widespread and diverse as late as the end of the Pliocene (about two million years ago) with representatives throughout most of Africa, Europe, and Asia. The descendants of the giant "hyracoids" (common ancestors to the hyraxes, elephants, and sirenians) evolved in different ways. Some became smaller, and evolved to become the modern hyrax family. Others appear to have taken to the water (perhaps like the modern capybara), ultimately giving rise to the elephant family and perhaps also the sirenians. DNA evidence supports this hypothesis, and the small modern hyraxes share numerous features with elephants, such as toenails, excellent hearing, sensitive pads on their feet, small tusks, good memory, higher brain functions compared with other similar mammals, and the shape of some of their bones. Hyraxes are sometimes described as being the closest living relative of the elephant, although whether this is so is disputed. Recent morphological- and molecular-based classifications reveal the sirenians to be the closest living relatives of elephants. While hyraxes are closely related, they form a taxonomic outgroup to the assemblage of elephants, sirenians, and the extinct orders Embrithopoda and Desmostylia. The extinct meridiungulate family Archaeohyracidae, consisting of seven genera of notoungulate mammals known from the Paleocene through the Oligocene of South America, is a group unrelated to the true hyraxes. List of genera Hyracoidea Dimaitherium Helioseus? Microhyrax Seggeurius Geniohyidae Brachyhyrax Bunohyrax Geniohyus Namahyrax Pachyhyrax "Saghatheriidae" Megalohyrax Regubahyrax Rukwalorax Saghatherium Selenohyrax Thyrohyrax Titanohyracidae Afrohyrax Antilohyrax Rupestrohyrax Titanohyrax Pliohyracidae Hengduanshanhyrax Kvabebihyrax Meroehyrax Parapliohyrax Pliohyrax Postschizotherium Prohyrax Procaviidae Dendrohyrax Gigantohyrax Heterohyrax Procavia Extant species In the 2000s, taxonomists reduced the number of recognized species of hyraxes. In 1995, they recognized 11 species or more, but as of 2013, only four were recognized, with the others all considered as subspecies of one of the recognized four. Over 50 subspecies and species are described, many of which are considered highly endangered. The most recently identified species is Dendrohyrax interfluvialis, which is a tree hyrax living between the