The hippopotamus, also shortened to hippo, further qualified as the common hippopotamus, Nile hippopotamus, or river hippopotamus, is a large semiaquatic mammal native to sub-Saharan Africa. It is one of only two extant species in the family Hippopotamidae, the other being the pygmy hippopotamus. Its name comes from the ancient Greek for "river horse" (ἱπποπόταμος).
Hippopotamidae is a family of stout, naked-skinned, and semiaquatic artiodactyl mammals, possessing three-chambered stomachs and walking on four toes on each foot. While they resemble pigs physiologically, their closest living relatives are the cetaceans. They are sometimes referred to as hippopotamids.
Palaeoloxodon is an extinct genus of elephant. The genus originated in Africa during the Pliocene, and expanded into Eurasia during the Pleistocene. The genus contains some of the largest known species of elephants, over 4 metres (13 ft) tall at the shoulders, including the African Palaeoloxodon recki, the European straight-tusked elephant and the South Asian Palaeoloxodon namadicus. P. namadicus has been suggested to be the largest known land mammal by some authors based on extrapolation from fragmentary remains, though these estimates are highly speculative. In contrast, the genus also contains many species of dwarf elephants that evolved via insular dwarfism on islands in the Mediterranean, some only 1 metre (3.3 ft) in height, making them the smallest elephants known. The genus has a long and complex taxonomic history, and at various times, it has been considered to belong to Loxodonta or Elephas, but today is usually considered a valid and separate genus in its own right.
Dwarf elephants are prehistoric members of the order Proboscidea which, through the process of allopatric speciation on islands, evolved much smaller body sizes in comparison with their immediate ancestors. Dwarf elephants are an example of insular dwarfism, the phenomenon whereby large terrestrial vertebrates that colonize islands evolve dwarf forms, a phenomenon attributed to adaptation to resource-poor environments and lack of predation and competition. Some modern populations of Asian elephants have also undergone size reduction on islands to a lesser degree, resulting in populations of pygmy elephants.
Għar Dalam is a 144 metre long phreatic tube and cave, or cul-de-sac, located in the outskirts of Birżebbuġa, Malta. The cave contains the bone remains of animals that were stranded and subsequently became extinct in Malta at the end of the Last Glacial Maximum. It has lent its name to the Għar Dalam phase in Maltese prehistory, and is viewed as one of Malta's most important national monuments. Pottery similar to that found in Stentinello was found at Għar Dalam, but lacking details such as stamp decorations.
Hippopotamus is a genus of artiodactyl mammals consisting of one extant species, Hippopotamus amphibius, the river hippopotamus, and several extinct species from both recent and prehistoric times. It belongs to the family Hippopotamidae, which also includes the pygmy hippopotamus and a number of extinct genera.
Palaeoloxodon falconeri is an extinct species of dwarf elephant from the Middle Pleistocene of Sicily and Malta. It is amongst the smallest of all dwarf elephants at only 1 metre (3.3 ft) in height. A member of the genus Palaeoloxodon, it derived from a population of the mainland European straight-tusked elephant.
Hippopotamus gorgops is an extinct species of Hippopotamus known from remains found in Northern and Eastern Africa as well as the Levant. It first appeared during the late Pliocene-Early Pleistocene, and became extinct during the early Middle Pleistocene.
Hexaprotodon is an extinct genus of hippopotamid known from Asia and possibly Africa and Europe. The name Hexaprotodon means "six front teeth" as some of the fossil forms have three pairs of incisors.
The Cypriot mouse is a species of mouse endemic to Cyprus. Its primary habitat seems to be the vineyards and fields of the Troödos Mountains region.
The Sardinian dhole is an extinct insular canid which was endemic to what is now the Mediterranean islands of Sardinia and Corsica during the Middle-Late Pleistocene. It went extinct at the end of the Pleistocene around the time of human settlement of the islands.
The Cyprus dwarf hippopotamus or Cypriot pygmy hippopotamus is an extinct species of hippopotamus that inhabited the island of Cyprus from the Pleistocene until the early Holocene. The 200-kilogram (440 lb) Cyprus dwarf hippo was roughly the same size as the extant pygmy hippopotamus. Unlike the modern pygmy hippo, the Cyprus dwarf became small through the process of insular dwarfism. H. minor is the smallest hippopotamus of all known insular hippopotamuses. It is estimated to have measured 76 cm (2.5 ft) tall and 121 cm (4.0 ft) long.
Hippopotamus antiquus is an extinct species of Hippopotamus that ranged across Europe during the Early and Middle Pleistocene.
Hippopotamus melitensis is an extinct hippopotamus from Malta. It lived during Middle-Late Pleistocene. It probably descended from Hippopotamus pentlandi from Sicily, which in turn probably descended from the common hippopotamus. Like Hippopotamus pentlandi, Hippopotamus melitensis is substantially smaller in size than H. amphibius as a result of insular dwarfism, having an estimated mass of approximately 900 kg, which is smaller than the 1100 kg estimated for H. pentlandi. The diet of H. melitensis is suggested to have been more generalist than Hippopotamus amphibius, likely as a result of limited resource diversity and lack of competition, as the only other large herbivore on the island was the dwarf elephant Palaeoloxodon mnaidriensis. The majority of findings of this species are from Għar Dalam, a cave on Malta famous for its Pleistocene fossil deposits.
Palaeoloxodon cypriotes is an extinct species of dwarf elephant that inhabited the island of Cyprus during the Late Pleistocene. Remains comprise 44 molars, found in the north of the island, seven molars discovered in the south-east, a single measurable femur and a single tusk among very sparse additional bone and tusk fragments. The molars support derivation from the large straight-tusked elephant (Palaeoloxodon antiquus). The species is presumably derived from the older, larger P. xylophagou from the late Middle Pleistocene which reached the island presumably during a Pleistocene glacial maximum when low sea levels allowed a low probability sea crossing between Cyprus and Asia Minor. During subsequent periods of isolation the population adapted within the evolutionary mechanisms of insular dwarfism, which the available sequence of molar fossils confirms to a certain extent. The fully developed Palaeoloxodon cypriotes weighed not more than 200 kg (440 lb) and had a height of around 1 m (3.28 ft). The species became extinct around 12,000 years ago, around the time humans first colonised Cyprus.
Hippopotamus creutzburgi, the Cretan dwarf hippopotamus, is an extinct species of hippopotamus from the island of Crete. It lived on the island from the Early Pleistocene to early Middle Pleistocene, and probably descended from Hippopotamus antiquus. It was considerably smaller than H. antiquus, weighing approximately 400 kilograms (880 lb). It was one of only two large herbivores on the island during its existence, alongside the dwarf mammoth Mammuthus creticus, with large predators being absent, the only other species of mammal present on the island being the giant rat Kritimys. It is known from abundant remains collected from the Katharo basin in the eastern uplands of Crete, approximately 1,100–1,200 metres (3,600–3,900 ft) above sea level, as well as much rarer remains found in coastal caves. Analysis of its limbs suggests that it was more adapted to terrestrial locomotion than living hippopotamus, primarily walking on its hooves rather than its footpads as in living hippopotamus, and capable of traversing the rugged terrain of Crete. Analysis of its teeth suggests that it had a grazing diet, similar to modern Hippopotamus amphibius. The previous suggestion that the species can be divided into two subspecies is not supported by modern research.
Palaeoloxodon mnaidriensis is an extinct species of dwarf elephant belonging to the genus Palaeoloxodon, native to the Siculo-Maltese archipelago during the late Middle Pleistocene and Late Pleistocene. It is derived from the European mainland straight-tusked elephant.
Hypnomys, otherwise known as Balearic giant dormice, is an extinct genus of dormouse (Gliridae) in the subfamily Leithiinae. Its species are considered examples of insular gigantism. They were endemic to the Balearic Islands in the western Mediterranean from the Early Pliocene until their extinction around 4,000 years ago. They first appeared in the fossil record on Mallorca during the Early Pliocene, presumably due to the Messinian salinity crisis causing a connection with mainland Europe. They later spread to Menorca, and a possible molar is also known from Ibiza. Hypnomys became extinct during the Holocene after human arrival on the Balearics. They were one of only three native land mammals to the islands at the time of human arrival, alongside the shrew Nesiotites and goat-antelope Myotragus.
Mammuthus creticus, or the Cretan dwarf mammoth, is an extinct species of dwarf mammoth endemic to Crete. It is only known from a single locality near Chania, which probably dates to the Early or Middle Pleistocene. With a shoulder height of about 1 metre (3.3 ft) and a weight of about 180 kilograms (400 lb), it was the smallest mammoth that ever existed. Its size reduction was the result of insular dwarfism, where the body size of large mammals on islands reduces as the result of decreased food availability, predation and competition. It was originally described as Elephas creticus by Dorothea Bate in 1907. After DNA research published in 2006, it was proposed to rename Elephas creticus into Mammuthus creticus. Others proposed to rename all the described specimens of larger size under the new subspecies name Elephas antiquus creutzburgi. A 2007 study criticised the results of the 2006 DNA study, showing that the DNA research was likely flawed. However, morphological data supports a placement in Mammuthus. It probably derived from Mammuthus meridionalis, or less likely, Mammuthus rumanus. It was one of only three mammal species native to Crete during the Early Pleistocene and the early Middle Pleistocene, alongside the dwarf hippopotamus Hippopotamus creutzburgi and the giant rat Kritimys.
Leithia is an extinct genus of giant dormice from the Pleistocene of the Mediterranean islands of Malta and Sicily. It is considered an example of island gigantism. Leithia melitensis is the largest known species of dormouse, living or extinct, being twice the size of any other known species.
