ALBERT

Description: A sirenian skeleton, the major part of which was excavated from Miocene deposits at Eibergen near Winterswijk, belongs to Metaxytherium. The temporal crests on the parietals are well separated. The foramen magnum is pointed above. The mandible has a downturned symphysial body with four shallow alveoli on each side. The wide mandibular canal opens some distance behind the alveolus of M3. There are alveoli for one premolar (P4) and for three molars (M1-M3). Only M2 dext. is preserved; it has four main cusps and some accessory cusplets. The humerus, the shaft portion of which is missing, has a wide and marked bicipital groove. The vertebrae, with the exception of the atlas, are fragmentary. The spinous processes are solid, the centra porous. The ribs, a few of which have been reassembled rather completely from fragments, are solid except for their vertebral ends. The distal, or sternal, ends may show a porous structure internally. In the sternum, the manubrium is separate, whereas corpus and ensiform process are co-ossified. The Eibergen sirenian appears indistinguishable from Metaxytherium medium (Desmarest) from the Helvetian of France.

Description: In 1876 beschreef Van Beneden (1876: 799) resten van een kleine zeehond uit het Scaldisien van het Bekken van Antwerpen als Phocanella minor.\nNewton (1891: 19/20) meldde een humerus fragment van deze soort afkomstig uit het Nodule Bed van de Red Crag bij Foxhall, 4 mijl Z.W. van Woodbridge in Suffolk. Een fragment van een femur werd door Van Deinse (1927: 1363) gerapporteerd van de Groeve van Wiegerink ten noorden van Zwolle; dit zou tot nu toe de enige fossiele vondst van Phocanella minor uit ons land zijn.\nHet zwarte botje waarvan hier nu melding wordt gemaakt ontving ik van Dr. P. H. de Buisonj\xc3\xa9 en is afkomstig van een schelpenzuiger in de Westerschelde. Het is een groot deel van het heiligbeen (sacrum), en de overeenkomst met het sacrum van Phocanella minor zoals dat door Van Beneden (1877, pl. 14 figs. 18-19) is afgebeeld is zo compleet als men zich slechts kan wensen. Het botje is afgerold en dus waarschijnlijk getransporteerd (zie pi. 1). De dorsale bogen van de sacrale wervels zijn verloren gegaan, en zo ook de linkervleugel van de eerste sacrale wervel. Aan beide zijden is het eerste sacrale foramen aan de ventrale kant bewaard gebleven.\nEnkele maten, voor zover die te nemen zijn (die van het vrijwel onbeschadigde, door Van Beneden afgebeelde sacrum tussen haakjes): lengte van de eerste en tweede sacrale wervel tezamen, 29 mm (31 mm); breedte over de vleugels van de eerste sacrale wervel, iets meer dan 40 mm (47 mm) ; idem over de wanden van de eerste ventrale sacrale foramina, 26 mm (30 mm) ; dorsoventrale doorsnede van het eerste sacrale wervellichaam, 15 mm (17 mm), en die van de vleugel, 24 mm (ca. 28 mm). Achter het tweede ventrale sacrale foramen is het laterale gedeelte afgebroken en is nog slechts een

Description: The Laetolil Beds in Tanzania, 20-30 miles south of Olduvai Gorge, have been extensively sampled by parties under the leadership of Mrs. Dr. Mary D. Leakey, who very kindly sent me Hipparion material collected in 1974, 1975, and 1976. In a restudy of proboscidean material from these beds described by Dietrich (1942), Maglio (1969) arrived at the conclusion that the Laetolil fauna represents two distinct horizons, one seemingly correlating best with Kanapoi, Yellow Sands (= Mursi Formation), Chemeron, and Kanam, and younger deposits correlating best with the later Omo Beds, possibly antedating Olduvai Bed I but only by a short time interval. This has been confirmed by radiometric dating: the Laetolil Beds with the older fauna are bracketed in time between 3.8 and 3.6 million years whereas the lava flows unconformably overlying them are dated at 2.4 million years. The younger deposits which are to be named Ndolanya Beds, therefore, have an age older than 2.4 million years, and have also produced fossils (Leakey et alii, 1976).\nThe fossiliferous deposits in the Laetolil area have been subdivided into 26 localities from most of which I received Hipparion material, all collected in situ. Two localities, 7 East and 18, are in the Ndolanya Beds, while the others are in the Laetolil Beds (Mary Leakey, personal communication). The fossils found in situ are cream coloured or white, sometimes chalky in texture. Surface material also including brown, grey or black specimens, often rolled, has been excluded. It is among the surface material that Equus is represented.\nHowever, there is no evidence that the equid material from the Laetolil Beds proper includes any genus but Hipparion.\nI am most grateful to Mrs. Mary Leakey for entrusting this material to me; it comes from a critical time phase in the evolution of African hipparions as

Description: Introduction................... 3\nThe Hipparion skull from \xce\x88\'Quarry............ 6\nThe upper dentition from \xce\x88\' Quarry............ 12\nThe mandibles from \xce\x88\' Quarry.............. 19\nThe lower dentition from \xce\x88\' Quarry............ 20\nLower premolars from a site between \xce\x88\' and \'C\' Quarries...... 26\nMetapodials from \xce\x88\' Quarry.............. 26\nProximal phalanx from \xce\x88\' Quarry............. 28\nFurther postcranial bones from \xce\x88 \'Quarry.......... 29\nHipparion from \xce\x88\' Quarry and Baard\'s Quarry compared....... 30\nEquus from Baard\'s Quarry.............. 33\nHow many species of Hipparion are represented at Langebaanweg?.............. 34\nConclusion................... 36\nSummary................... 37\nAcknowledgements................. 37\nReferences................... 38\nINTRODUCTION\nThe site of Langebaanweg, situated approximately 32\xc2\xb058\' S, 18\xc2\xb09\' \xce\x95 in the Sandveld region of the southwestern Cape Province, some 105 km NNW of Cape Town, first came into the palaeontological picture in 1958, when the find of a fossil proboscidean, erroneously called Stegolophodon (Singer & Hooijer, 1958), was published from this site. The remains of Equidae (Hipparion) from Baard\'s Quarry and from a second quarry, called Varswater, later named \'C\' Quarry, were the subject of a paper by Bon\xc3\xa9 & Singer (1965), but better material, mainly from \xce\x88\' Quarry, has since been collected. The

Description: CONTENTS\nIntroduction and acknowledgements............ 3\nSome notes on working methods............. 5\nSpecies of Hipparion in Africa............. 6\nHipparion primigenium (Von Meyer)............ 12\nHipparion turkanense Hooijer & Maglio........... 19\nHipparion? aff. sitifense Pomel............. 22\nThe Olduvai Gorge Hipparion: Hipparion cf. ethiopicum (Joleaud) .... 26\nThe Omo Group Hipparion: Hipparion spec. and Hipparion ethiopicum (Joleaud) 52 References................... 73\nExplanation of the plates............... 76\nINTRODUCTION AND ACKNOWLEDGEMENTS\nHipparion De Christol, 1832, comprises extinct tridactyl equids typified by their isolated protocones, which evolved in North America from Merychippus stock, and invaded the Old World 12.5 million years ago. Gone are the days when Hipparion was considered ancestral to Equus, but to this day sweeping conclusions are being drawn about some reduction in the length of the side metapodials relative to the median metapodial from the oldest to the youngest forms, whereas in reality all there was is allometric growth (cf. Forsten, 1973a). In her plea for the new systematics, with polytypic rather than local and chronologically limited species, Forsten (1973b) observes that since 1829, when the first finds were described by Von Meyer, until about 1930 new species of Hipparion have been described at a mean rate of one every three years. Since 1930, the mean rate of increase in the number of species described as new in Hipparion has been two every three