Superfamily Hippopotamoidea 19 Jan van de, Made* The superfamily Hippopotamoidea includes two the anthracotheres.PICKFORD (1983) assumed that families, the Anthracotheriidae and the Hippopo- hippos evolved from Xenohyus (Suidae), which in tamidae. Hippopotamoidea are "suiform" animals. turn evolved from Doliochoerus (Palaeochoeridae), This term refers mostly to retention of primitive sIl Tayassuidae (= Dicotylidae) in his opinion. artiodactyl characters such as separate metapodi- This would place the hippos in the superfamily BIs (usually tour metapodials; in soma anthraco- Suoidea and the anthracotheres in the Anthraco- 1.-t theres five metacarpals), the lateral metapodials therioidea. However, numerous dental, cranial and being relatively large, navicular and cuboid not postcranial characters, as well as characters of j fused, astragalus with proximal and distal troch- the soft tissues argue against this modelo t lea making an angle, complete fibula, presente of upper incisors, etc. The enamel of the cheek teeth is generally crenelated. Anthracotheres have se- Evolutionary history of the Miocene lenodont or buno-selenodont molars: the lingual European Hippopotamoidea GRAY.1821 cusps in the upper molars and the buccal cusps in the lower molars have the shape of a crescent. AnthracotheriidaelElDY, 1869: Anthracotheriidae Hippo molars have trefoil shaped cusps, which were common in Europe during the Oligocene. resulted as a modification of the anthracothere The most common forms were the large buno- selenodont pattern. Incisors and canines became selenodont Anthracotherium, the much smaller very large in hippos. The crowns of the incisors selenodont Elome/yx, and the very sma" bu no- wear off rapidly, but the teeth keep growing. selenodont Microbunodon. ElomelYX persisted Most hippos have the orbita in an elevated into the earliest part of the Miocene. position, as an adaptation to an aquatic lifestyle. The same character evolved parallel in the later Elomeryx MARsH,1894: The genusElomefY)( con- anthracotheres. Living species of hippos tend to tains small selenodont anthracotheres with com- spend large parts of the day in the water. During plete dentition, upper molars with distinct proto- the night they leave water to graze, but usually preconule (nomenclature of VAN DERMADE 1996) are not more than some kilometres away from the or protoconule. large canines. all incisors incisi- nearest river or lake. More or less similar habits form, small diastemata. low elongate skulls with are usually assumed for the anthracotheres. orbitae not or not much elevated. E. borbonicus Anthracotheriidae are first known from the (GERVAlS.1849) is known from three Miocene Eocene of Asia and Europe and the Oligocene of localities. The specimens from Pyrimont were I Africa and America. During the Early Miocene initially described as the variety minar of the I they went extinct in America and the mainland of species E. borbonicus. SCHAUB(1948) described Europe, but lived on till the Late Miocene in Africa material of two other Aquitanian localities and elevated minar to species rank on the basis of 1: and till the Plio-Pleistocene in southern Asia. In Europe they reappeared once again, during the small skull size and the small size of the premolars Early Miocene another form seems to have lived compared to the molars. HELLMUND(1991) revised on on a Mediterranean island. the genus and did not recognize the subspecies. The Hippopotamidae evolved in Africa during However. the premolars of the Miocene form are the Early Miocene. They reached southern Asia indeed smaller than those of the Oligocene form and Europe during the latest Miocene. In Europe and I am inclined to recognize the subspecies they went extinct, but re-entered during the Pleis- E. borbonicus minar. tocene. There were several Pleistocene endemic species on several Mediterranean islands and on Brachyodus DEPÉRET.1895: The genus Brschyo- Madagascar. There are two living species in Afri- dus is characterizedby selenodontmolars with a distinct protopreconule.reduced first upper inci- ca (CORYNDON1978). Most workers agree that hippos evolved from sors and either caniniform and enlarged third (DINEUR & GINSBURG 1986) or second (HELLMUND * Dr. Jan van der Made, Museo Nacional de Ciencias 1991) lower incisors. reduced other InclsorS. low Naturales, José Gutiérrez Abascal, 2, E-28006 Ma- elongate skulls with long diastemata and orbitae drid, Spain not or not much elevated. The Mlocene ~nd Mammals of Europe. - pp. 203-208. 203 Fig. 19.1. Right mandible with P2-M3 01 Br8chyodus There seems to be a consensus that Brachyo- ENGESSER(1989) assumed a migrationfrom onoideus from Neuville- dus evolved from the Oligocene anthracotheres Africa during the early Late Miocene bringing the aux-Bois (MSNO 914), primate Oreopithecus and the anthracothere to holotype. The bar repre- known from the Fayum in Egypt (PICKFORD1991). sents 5 cm. When, after a long period of isolation, in the Earty the island. HÜRZELERreferred to Microbunodon, a Miocene (MN 3) Africa beca me connected to Eur- bunodont anthracothere. The tooth (Iabelled as asia Brachyodus dispersad to Europe (DINEUR & from Ribolla) is indeed bunodont. Alllater anthra- GINSBURG 1986), the Indian Subcontinent (PICK- cotheres are selenodont. The last bunodont an- FORD 1987), Asia north of the Himalayas (VISlO- thracotheres from Europe are from the Oligocene: BOKOVA1994) and Japan (TAKAI 1954, as cited by the very small Microbunodon and the very large TASSY 1990). Anthracotherium. In India Anthracotherium sur- In Europe, Brachyodus is representad by a vived into the the Early Miocene (PICKFORD1987) lineage that is characterized by increase in size, and a small bunodont anthracothere is known the small B. íntermedíus (early MN 3) evolved into from Middle Miocene strata of the Chinji Forma- the larger B. onoídeus (late MN 3 and MN 4) (DINEUR tion (COLBERT1935). AlI Neogene anthracotheres & GINSBURG1986). described by PICKFORD(1991) from Africa are selendont. However, a tooth from Malembe that Anthracotherium CUVlER,18221: HÜRZELER(1982) HOOIJER(1963) made the type of Hyotherium states that a lower third molar from Casteani, that dartevelle; was recognized by PICKFORD(1986) as WEITHOFER(1888, as citad by HÜRZELER)assigned anthracothere. This tooth is bunodont and small to a species of suid, in reality belongs to an and is probably from the Lower Miocene. Mor- anthracothere of the size of a large Microbuno- phologically the tooth from Italy fits best Anthra- don. cotherium. Large mammals tend to reduce their The locality of Casteani is in the lower levels of size in endemic island environments (SONDAAR the Bacinello basin (Italy). Faunas from these 1986), in the case of suitorms this may be as f levels are late Miocene and their composition much as some 25% (VAN DERMADE 1988). AII indicates that central ltaly at that time was an bunodont anthracotheres mentioned are smaller island (ENGESSER1989). The faunas are poor in than the animal from Casteani, save for Anthraco- species, with few carnivores no ther;um. tyls, and the species present A calcaneum from the early Miocene of Os- that are typical of endemic The chiri (Sardinia) might be an anthracothere. It sug- island may have centralltaly gests an animal roughly of the same size as the as well as Corsicaand tuscan anthracothere. The fauna from Oschiri is supposed to be earliest Miocene (De BRUIJN& 204 ~ RÜMKE 1974).Corsica and Sardiniawere first con- nected to the mainland of France, but more or less during the Late Oligocene, they became is- lands (compare RóGL& STEININGER1983 and DER- COURTet al. 1986). Later these islands moved towards the island formed by central ltaly. The presente of Oreopíthecuson Sardinia (CORDY& GINESU1994) suggests that during the Late Mio- cene Sardinia and central ltaly were connected and formed one large island. In any case, we have to assumethat a buno- dont anthracothere survived millions of years isolated on an island, while the mainland buno- dont anthracothereswent extinct. It is possible that Anthracotherium was present on Sardinia when this area separatedfrom southern France and became an island, or that it got to Sardinia shortly after it became an island. The animal reduced its size and possibly aquired other adap- tations that are typical of island species. When Sardinia became connectedto the central ltalian island,the anthracotheresdispersed into that area as well. Hippopotamidae GRAV, 1821: The oldest hippo known, is a tooth from Rusinga in East Africa (CORYNDON1978). Deposits at Rusinga are about Ag. 19.2. Symphysis with 18 Ma old (PICKFORD1986). Kenyapotamus from 11-2of Hexaprotodon? pan- deposits that are slightly younger is the earliest tBnellii from La Portera well known hippo (PICKFORD1983). The genus (MNCN). The bar repre- Hexaprotodon appeared some 7 Ma ago. The sents 5 cm. name refers to the number of incisors in the lower jaw. three on each side; there is an equal number of incisors in the upper jaw. Later species of this genus may have as few as two incisors in each upper and one in each lower jaw. During the Late Miocene, hippos dispersed to Europe and south- ern Asia. In the Indian Subcontinent and Indone- sia, Hexaprotodon (with a full set of incisors) lived and evolved well into the Pleistocene. The form that migrated to Europe is currently placed in Hexaprotodon, but is different from the southern Asian lineage in being tetraprotodont (with only tour incisors in the lower jaw). The living Hexa- protodon liberiensis is the last representative of the genus. Hippopotamus evolved in Africa ~ from Hexaprotodon. AII species in this genus are tetraprotodont. This genus dispersed during the Pleistocene to Europe, but not to southern Asia. The living representative is Hippopotamus am- phibius. Ag. 19.3. Left mandible Hexaprotodon FALCONER& CAUTlEY,18361: Sev- with P3-M, of Hexaproto- eral hippos were described from the circum Med- don? pantane/lii from La iterranean area: Hippopotamuspantanellii JOLE- Portera (MNCN). The bar AUD, 1920 from Casino in ltaly, Hippopotamus represents 2 cm. 205 1986).This shows that the hippos that dispersed during the late Mioceneto Europeand Asia were different; the Indian and Indonesian hippos had three incisors in both jaws.