Cypriot pygmy hippopotamus

The Cypriot pygmy hippopotamus (Hippopotamus minor or Phanourios minor) is an extinct species of dwarf hippopotamus that inhabited the island of Cyprus from the Pleistocene until the early Holocene.

History of discovery and taxonomy
Bones of fossil mammals have been known on Cyprus since at least the 15th century, when Cypriot historian Leontios Machairas reported that bones exposed in the Kyrenia/Pentadactylos mountains in the northern part of Cyprus were believed by locals to be the bones of Maronite Christians who had fled to the island, which they regarded as saints. An account from a later historian, Benedetto Bordone published in 1528, reporting on a similar deposit in the Kyrenia mountains, recounted that locals ground the bones into powder to make a potion they thought could cure many diseases. In 1698, the Dutch traveller Cornelis de Bruijn, remarking on another Kyrenia mountains bone deposit, made several images of bones he found, which he thought were deposited by the Biblical great flood. The remains in one of these images, which he identified as human, is now retrospectively identified as remains of the Cypriot pygmy hippopotamus.

The earliest scientific description of the species was given by French paleontologist Anselme Gaëtan Desmarest in 1822, who gave the current name Hippopotamus minor. The species Hippopotamus minutus named shortly after by Georges Cuvier in 1824 is now regarded as a junior synonym. Both authors were unaware of the origin of the specimens which were in the collections of a French museum in Paris, with Desmarest and Cuvier both suggesting that the specimens originated from southern France. Additional remains of the species were collected from Cyprus by British paleontologist Dorothea Bate in 1901, which led Charles Immanuel Forsyth Major to recognise material in the Paris collection as also originating from Cyprus. The species is now known from over 20 localities across the island. In 1972, the species was placed in the new genus Phanourios by Paul Yves Sondaar and Gijsbert Jan Boekschoten after Saint Phanourios which local Cypriots associated with its bones. However this placement has been questioned due to the fact that it is widely agreed that the species descends from a species of the genus Hippopotamus, and other authors have continued to use the combination Hippopotamus minor.

Evolution
A partial mitochondrial genome obtained from H. minor suggests that its closest living relative is the common hippopotamus (Hippopotamus amphibius), with an estimated genetic divergence between 1.36 to 1.58 million years ago. The ancestor of the Cypriot pygmy hippopotamus is uncertain, but is likely either H. amphibius or the extinct species Hippopotamus antiquus. The timing of the colonisation is uncertain, though the earliest fossils date to around 219-185,000 years ago, during the late Middle Pleistocene. Due to Cyprus never having been connected to the mainland, its ancestors must have arrived via crossing the Mediterranean, perhaps as the result of a rare cataclysmic flooding event. Its small body size is due to insular dwarfism, a common phenomenon on islands.

Description and ecology
The Cypriot pygmy hippopotamus was roughly the same size as the extant African pygmy hippopotamus (Choeropsis liberiensis), with an estimated body mass of around 130 kg. H. minor is the smallest of all known insular hippopotamuses. It is estimated to have measured 70 cm tall and 125 cm long. Compared to H. amphibius, the muzzle region of the skull is much shorter, and the skull as a whole resembles that of the pygmy hippopotamus. Unlike other species of the genus Hippopotamus, the lower fourth premolar has been lost.  The teeth of H. minor are more brachydont (less high crowned) than those of H. amphibius, suggesting that H. minor probably occupied a browsing niche, in contrast to the grazing predominant diet of modern Hippopotamus amphibius, though its diet is likely to have varied in correspondence to glacial cycle-induced climatic changes. Analysis of the limb and hand bones suggests that it was more terrestrial than its living relatives, and capable of moving on the rugged terrain of Cyprus, with changes including the shortening of the distal (closest to foot) part of the legs, and increased robustness of the limb bones, though it was likely incapable of running quickly.

Paleoenvironment
During the Late Pleistocene, the Cypriot pygmy hippopotamus, along with the similarly sized Cyprus dwarf elephant, were the only large mammals native to the islands, and one of only four native terrestrial mammal species, alongside the still living Cypriot mouse and the extinct genet species Genetta plesictoides, and had no natural predators. Remains of the dwarf hippopotamus are abundant at localities where it is found, considerably moreso than the dwarf elephant.

Extinction
The youngest remains of the species date to the end of the Pleistocene, around 13-12,000 years ago, around the same time as the youngest remains of the dwarf elephant species. These dates roughly coincide with the oldest evidence of human habitation of Cyprus. Over 200,000 bones of H. minor, representing over 500 individuals, are associated with human artifacts at the Aetokremnos rockshelter on the southern coast of Cyprus, dating to approximately 13-12,000 years Before Present, representing among the youngest records of the species, which is suggested by some authors to provide evidence that the Cypriot pygmy hippopotamus was hunted and driven to extinction by the early human residents of Cyprus. However, these suggestions have been contested, in part due to a lack of cut marks on the bones that would definitively indicate butchery, with an alternative proposal that bones at Aetokremnos accumulated naturally over hundreds of years, with the human occupation of the site after the bones were initially deposited.