New species of bushbaby from the middle Miocene of Maboko Island, Kenya.

A mandible recovered from ca. 15 million year old deposits of Maboko Island, Kenya, represents the first bushbaby known from the middle Miocene. The specimen is from a new species of Komba, a genus previously known from early Miocene occurrences in western Kenya and northeastern Uganda. Komba is revised, with emended diagnoses proposed for the genus, type-species, and referred species. Komba sp. nov. is distinguished by its larger size and differences of molar cusp acuity, buccal cingulum expression, and mental foramen configuration. Contrary to previous opinion, species of Komba probably diverged prior to the last common ancestor of extant Galaginae, and it is unlikely that they represent early stages of living bushbaby species lineages. Although contemporary Progalago is widely regarded as a galagine, aspects of upper molar, lower premolar, and mandibular corpus morphology indicate that it is more closely related to lorisines. Unlike the greater success currently enjoyed by bushbabies, lorisines were more diverse and almost as abundant as galagines in the early Miocene of eastern Africa.     

An oreopithecid proximal humerus from the middle miocene of Maboko Island,Kenya

A proximal humerus, recently recovered from the middle Miocene of Maboko Island, Kenya, provides the earliest evidence of postcranial structure and adaptation of Oreopithecidae. Provisionally attributed toNyanzapithecus pickfordi (Harrison, 1986), the specimen manifests a globose head, subequally large tuberosities, and a board, shallow bicipital groove. Although readily distinguished from the fundamentally cercopithecoid proximal humeral morphology ofVictoriapithecus (Senut, 1986), the Maboko Island oreopithecid, shows none of the derived features that are characteristic of the proximal humeri of extant hominoids. It is inferred from proximal humeral anatomy that the Maboko Island oreopithecid was an active arboreal scansor with moderate mobility at the shoulder but lacking adaptations for circumduction of the arm. In combination with craniodental evidence, proximal humeral morphology indicates that Oreopithecidae was a clade of hominoids which originated before the last common ancestor of extant apes and went extinct, without issue, in the later Miocene.     

Taphonomy of the early Miocene flora, Hiwegi Formation, Rusinga Island, Kenya

A fossil flora was collected in situ from early Miocene deposits at site R117 in the Hiwegi Formation of Rusinga Island contemporaneous with and in close proximity to the sites from where the anthropoid primates were recovered. The flora exhibits a spatially and temporally patchy distribution of fruits and seeds, mixed with twigs of various sizes, fragments of wood, bark, and leaves, all with random orientations and very low depositional dips. There has been minimal transport and the flora evidently accumulated as in situ litter beneath local vegetation. Based on Nearest Living Relatives (NLR) of fruits and seeds, the vegetation represented is a deciduous broad-leaved woodland with continuous canopy, with trees, shrubs, lianas, and climbers, reminiscent of the structure of the modern vegetation in the steep-sided protected valleys in the Laetoli-Endulen area. The interpretation of the vegetation is supported by the presence of twigs, wood, and bark fragments from larger diameter axes. Climbers are represented by twining stem fragments as well as by a wide variety of distinctive fruits and seeds. The proportion of fossilised thorny twigs represents only 3% of the twig collections, and there are no unequivocal forest trees amongst the NLR. No grasses were present; monocotyledons are only represented by a single date palm stone. No conifer seeds or cones have been recovered, and there are no coniferous leafy shoots.     

Paleosols and paleoenvironments of the middle Miocene,Maboko Formation,Kenya

The middle Miocene (15 Ma) Maboko Formation of Maboko Island and Majiwa Bluffs, southwestern Kenya, has yielded abundant fossils of the earliest known cercopithecoid monkey (Victoriapithecus macinnesi), and of a kenyapithecine hominoid (Kenyapithecus africanus), as well as rare proconsuline (Simiolus leakeyorum, cf. Limnopithecus evansi) and oreopithecine apes (Mabokopithecus clarki, M. pickfordi), and galagids (Komba winamensis). Specific habitat preferences can be interpreted from large collections of primate fossils in different kinds of paleosols (pedotypes). Fossiliferous drab-colored paleosols with iron-manganese nodules (Yom pedotype) are like modern soils of seasonally waterlogged depressions (dambo). Their crumb structure and abundant fine root-traces, as well as scattered large calcareous rhizoconcretions indicate former vegetation of seasonally wet, wooded grassland. Other fossiliferous paleosols are evidence of nyika bushland (Ratong), and early-successional riparian woodland (Dhero). No fossils were found in Mogo paleosols interpreted as saline scrub soils. Very shallow calcic horizons (in Yom, Ratong, and Mogo paleosols) and Na-montmorillonite (in Mogo) are evidence of dry paleoclimate (300-500 mm MAP=mean annual precipitation). This is the driest paleoclimate and most open vegetation yet inferred as a habitat for any Kenyan Miocene apes or monkeys. Victoriapithecus was abundant in dambo wooded grassland (Yom) and riparian woodland (Dhero), a distribution like that of modern vervet monkeys. Kenyapithecus ranged through all these paleosols, but was the most common primate in nyika bushland paleosols (Ratong), comparable to baboons and macaques today. Mabokopithecus was virtually restricted to riparian woodland paleosols (Dhero), and Simiolus had a similar, but marginally wider, distribution. Habitat preferences of Mabokopithecus and Simiolus were like those of modern colobus monkeys and mangabeys. A single specimen of Komba was found in dambo wooded grassland paleosol (Yom), a habitat more like that of the living Senegal bushbaby than of rainforest galagids. A shift to non-forest habitats may explain the terrestrial adaptations of Victoriapithecus, basal to the cercopithecid radiation, and of Kenyapithecus, basal to the hominoid radiation. Both taxa are distinct from earlier Miocene arboreal proconsulines, oreopithecines and galagids.     

壳斗科的地质历史及其系统学和植物地理学意义

在收集整理现有壳斗科化石资料的基础上,讨论了壳斗科及其各属的起源时间、地史分布和地史 演替过程以及这些化石资料在系统学和植物地理学上的意义。白垩纪尚无壳斗科可靠的大化石记录, 微化石需要进一步研究才能确定亲缘关系以及古新世壳斗科已经分化出两个类群。从以上这些事实推 论壳斗科起源于白垩纪晚期,而壳斗科现代各属出现的时间应不晚于古新世。最早发现的壳斗科化石和现代栗亚科和水青冈亚科在形态结构上非常相似,这一事实表明,壳斗科分为两个亚科的观点更接近客观事实。在水青冈亚科中,三棱栎类的化石最早出现;在栎属中,青冈亚属更接近祖先类群;在地史中全缘栎类较具齿栎类出现早,粗齿的落叶栎类出现最晚。三棱栎属、栲属和石栎属的化石在老第三纪出现于北美和欧洲的事实说明,北美、欧洲和东亚在老第三纪时有一个相通的壳斗科植物区系。南美的三棱栎是通过北美进入南美的。中国横断山、欧洲地中海沿岸和北美西北部有一类形态特征相似、亲缘关系相近的硬叶栎类,它们之间有相同的地质演替历史,它们现代分布边界可能就是古地中海的边界。美洲的栎类有两个来源,常绿硬叶栎类是通过古地中海沿岸而经北美-欧洲陆桥到达的,落叶栎类则是在中新世以后通过白令海峡到达的。     

The anatomy and systematic position of the early Miocene proconsulid from Meswa Bridge, Kenya

A small collection of fossil catarrhines was recovered from the early Miocene locality of Meswa Bridge in western Kenya between 1978 and 1980. The associated fauna from Meswa Bridge indicates an age older than 20 Ma. Much of the material has been briefly described previously, and its taxonomic status considered. The material can be assigned to a minimum of four individuals, all of which are infants or juveniles. Although the specimens were shown to belong to a distinct species of Proconsul, the taxon was not named, primarily because many of the specimens belonged to immature individuals. Nevertheless, the combined morphological features of the deciduous and permanent teeth allow the diagnosis of a new species of Proconsul, which is formally named here as P. meswae. It is a large-sized species, similar in dental size to P. nyanzae. The main features distinguishing it from all other previously named species of Proconsul are: incisors and deciduous incisors relatively low crowned; upper deciduous canines relatively higher crowned and more robust; molars and deciduous premolars relatively broader and higher crowned, with a more pronounced degree of buccolingual flare and better developed cingula; size differential between molars not as marked; dP₄ with a longer mesial fovea and smaller hypoconulid and distal fovea; P₄ relatively broader, with a better developed buccal cingulum; lower molars less rectangular with a longer mesial fovea, smaller distal fovea, more restricted talonid basin, and a tendency for a smaller hypoconulid; dP⁴ and upper molars with strongly buccolingually splayed roots; mandibular corpus in infants relatively deeper and more slender; maxilla with a well developed canine jugum and fossa. The broader and more flared molars with better developed cingula indicate that the Meswa Bridge species is more primitive than other species of Proconsul. The inference that it is a stem member of the Proconsul clade is consistent with the estimated age of the material.     

A New Rhinoceros, Victoriaceros kenyensis gen. et sp. nov., and Other Perissodactyla from the Middle Miocene of Maboko, Kenya

The middle Miocene site of Maboko (Lake Victoria, Kenya), dated to ca. 15 Ma, has yielded one of the best collection of rhinos in Africa. The most common taxon, Victoriaceros kenyensis n.gen., n.sp., is represented by an almost perfect skull (whose main features are the large nasal horn, an orbit located very anteriorly and with a prominent border, and very broad zygomatic arches) and numerous limb bones, probably belonging to only a few individuals. Characters of the teeth and skull support an assignment to the subfamily Elasmotheriinae, a group best known in the middle and upper Miocene, but whose monophyly is disputable, as some of their tooth characters could be adaptations to a grazing diet (in agreement with their distribution in the Maboko beds). In any case, Victoriaceros clearly differs from other East African middle Miocene rhinos, whose diversity is far greater than currently assumed. A few other specimens attest to the occurrence at Maboko of at least one other species, perhaps close to the brachypotheres; a single calcaneum is tentatively assigned to the Chalicotheriidae.     

Nacholapithecus skeleton from the Middle Miocene of Kenya

An almost entire skeleton of a male individual of Nacholapithecus kerioi (KNM-BG 35250) was discovered from Middle Miocene (approximately 15 Ma) sediments at Nachola, northern Kenya. N. kerioi exhibits a shared derived subnasal morphology with living apes. In many postcranial features, such as articular shape, as well as the number of the lumbar vertebrae, N. kerioi resembles Proconsul heseloni and/or P. nyanzae, and lacks suspensory specializations characteristic of living apes. Similarly, N. kerioi shares some postcranial characters with Kenyapithecus spp. However, despite the resemblance, N. kerioi and Proconsul spp. are quite different in their body proportions and some joint morphologies. N. kerioi has proportionally large forelimb bones and long pedal digits compared to its hindlimb bones and lumbar vertebrae. Its distinctive body proportions suggest that N. kerioi was more derived for forelimb dominated arboreal activities than P. nyanzae and P. heseloni. On the other hand, it exhibits a mixture of derived and primitive cranio-dental and postcranial features relative to the contemporaneous Kenyapithecus and Early MioceneMorotopithecus. While the phylogenetic position of N. kerioi is unsettled, it seems necessary to posit parallel evolution of cranio-dental and/or postcranial features in fossil and living apes.     

Taxonomic affinities of the enigmatic Prionogale breviceps,early Miocene,Kenya

Prionogale breviceps is a tiny carnivorous mammal from the early Miocene of eastern Africa. Originally, specimens were interpreted as the adult morphology of the taxon. The dentition did not obviously align Prionogale with the carnivorous lineages present in Afro-Arabia during the early Miocene: Hyaenodonta and Carnivora. When Namasector was discovered in Namibia, the small taxa were placed together in Prionogalidae and aligned with Hyaenodonta. In this study, based on comparisons to hyaenodont specimens preserving deciduous dentition, the holotype of Prionogale is reinterpreted as preserving dP3 and dP4. Some of the lower dental specimens attributed to the taxon preserve dp4. The holotype of Namasector also preserves deciduous dental material. A phylogenetic analysis that includes deciduous dental characters for a broader sample of hyaenodonts resolved Prionogalidae as a clade. Understanding of the deciduous dentition of Prionogale allows future analyses to compare homologous morphology, and to explore the environmental factors that shaped carnivorous mammal evolution through the Miocene.     

New material and revision of hipparions from the upper Miocene locality Ravin des Zouaves-5, RZO of Axios Valley (Macedonia,Greece)

The reconsideration of the hipparions from the locality Ravin des Zouaves-5 (RZO) of the lower Axios Valley provides a better taxonomy, based on the revision of the old known collection (up to 1987), the inclusion of new discoveries and the bibliographic data of the last 30 years related to the study of the hipparions in Greece and the neighboring countries. Based on the cranial material and metapodials, five different taxa have been distinguished. New cranial material confirms the presence of the large-sized Hipparion proboscideum and the small-sized Hipparion macedonicum in the RZO fauna. In the new middle-sized hipparion sample from RZO two species have been identified, Hipparion philippus, and another form similar to Hipparion mediterraneum, which is attributed to Hipparion cf. mediterraneum. Cranial remains of a second small-sized hipparion are also recognized in the RZO fauna, which is attributed to Hipparion sithonis. The relationships of H. mediterraneum and H. proboscideum are discussed; a cladistic analysis suggests that they are sister taxa, sharing a common ancestor with the Hipparion moldavicum group, and a form similar to H. mediterraneum is a possible ancestor of H. proboscideum.     

Bony‐toothed birds (Aves: Pelagornithidae) from the Middle Eocene of Belgium

Abstract: We describe well‐preserved remains of the Pelagornithidae (bony‐toothed birds) from the middle Eocene of Belgium, including a sternum, pectoral girdle bones and humeri of a single individual. The specimens are tentatively assigned to Macrodontopteryx oweni Harrison and Walker, 1976 , which has so far only been known from the holotype skull and a referred proximal ulna. Another species, about two times larger, is represented by an incomplete humerus and tentatively identified as Dasornis emuinus ( Bowerbank, 1854 ). The fossils provide critical new data on the osteology of the pectoral girdle of bony‐toothed birds. For the first time, the sternum of one of the smaller species is preserved, and this bone exhibits a more plesiomorphic morphology than the recently described sternum of the giant Miocene taxon Pelagornis. The coracoid resembles that of the Diomedeidae (albatrosses) in overall morphology, but because bony‐toothed birds lack apomorphies of the Procellariiformes, the similarities are almost certainly owing to convergence. Bony‐toothed birds were often compared with the ‘Pelecaniformes’ by previous authors, who especially made comparisons with the Sulidae (gannets and boobies). However, the coracoid distinctly differs from that of extant ‘pelecaniform’ birds, and the plesiomorphic presence of a foramen nervi supracoracoidei as well as the absence of a well‐delimited articulation facet for the furcula supports a position outside the Suloidea, the clade to which the Sulidae belong.     

First substantial Middle Eocene record of the Lithornithidae (Aves): A postcranial skeleton from Messel (Germany)

A postcranial skeleton of a representative of the palaeognathous Lithornithidae (Aves) is described from the Middle Eocene of Messel in Germany. The specimen is slightly smaller than Lithornis plebius from which it, however, differs in limb bone proportions. It constitutes the latest fossil record of the Lithornithidae in Europe, whose only other Middle Eocene record is a fragmentary tibiotarsus from North America.     

Geology and fauna of the middle Miocene hominoid site at Muruyur,Baringo district,Kenya

The middle Miocene sediments assigned to the Muruyur Beds have yielded abundant faunal remains which indicate an age somewhere near the early part of the middle Miocene, perhaps being earlier in time than Fort Ternan but probably coeval or slightly later than Maboko. Available radioisotopic age determinations suggest that the beds are between 13.5 and 14 m.y. old, which seems to be too young when compared with the biostratigraphic estimate. The importance of Muruyur Beds lies in their rich fossil content which includes hominoids of an age which is in general poorly represented in East Africa’s fossil record. This article places the fossil discoveries on record, and discusses their geological context.     

Hominid molars from a Middle Stone Age level at the Mumba Rock Shelter, Tanzania

Three hominid molars were recovered from a depth of 7.0-7.1 meters in the Mumba Shelter at Lake Eyasi, northern Tanzania. Geological context of the finds and archaeological data indicate that people with a Middle Stone Age technology were using the Mumba locality intermittently whenever retreat of lake waters allowed access to the site. Uranium series dates suggest an age on the order of 130,000 years bp for the teeth and stone tools. Based on morphological analyses, the dental remains probably belonged to one individual and appear to be the crowns of two upper permanent M2s and one lower permanent M2. Crown areas are very small, even in comparison to the variation exhibited by recent African populations. Crown patterns have no archaic features. These teeth are smaller than any verifiable archaic Homo sapiens examples; thus, they may represent early anatomically modern Homo sapiens.     

On the morphology of spermatozoa in some African murines (Rodentia, Muridae): the taxonomic and phylogenetic aspects

A comparative analysis of sperm-head morphology and measurements in 17 species from nine genera of African Murinae: Rattus rattus, Mastomys coucha, M. huberti, M. erythroleucus, Mastomys sp. 2, Praomys albipes, P. fumatus, Mus mahomet, Arvicanthis somalicus, A. abyssinicus, A. dembeensis, Arvicanthis sp., Lemniscomys macculus, Pelomys harringtoni, Acomys cahirinus, Acomys sp., Uranomys ruddi, was carried out. Spermatozoa of all examined species are of the same basic type. They consist of an asymmetrical head, falciform or scythelike in shape, and a tail attached to the ventrocaudal surface of the head. There are great interspecific differences in sperm morphology and size. The significance of this variation for estimation of taxonomic aspects and phylogenetic relationships among the species, as well as between them and other groups, is discussed. The sperm morphology supports a close evolutionary relationship among the genera Lemniscomys and Arvicanthis. It also indicates that Pelomys is distinctive. The relationships between Acomys and Uranomys are discussed.     

Miocene Sanitheriidae (Suiformes, Mammalia) from Namibia and Kenya: systematic and phylogenetic implications

Sanitheres are enigmatic small suoids with bunoselenodont cheek teeth and a tendency for complication of the premolars by polycuspy and polycristy. Until a few years ago virtually nothing was known about their anterior dentition, but recent discoveries in Greece, Kenya and Namibia have thrown light on their incisor and canine morphology, and reveals among other things that the canines are highly sexually dimorphic, and the dm/1 is replaced by a p/1. Material from Kipsaraman, Kenya, collected between 1997 and 2003, consists of parts of mandibles and many isolated teeth, including elements of the deciduous dentition, a significant proportion of which are unworn. These new finds confirm the aberrant nature of the sanithere dentition within a suoid framework, and support their classification as a family separate from Suidae and Palaeochoeridae (= Old World Tayassuidae).

Résumé

Les sanithères sont de petits Suoïdes aux dents jugales bunosélénodontes avec des prémolaires qui présentent une tendance à la multiplication des cuspides et des crêtes (“polycuspidie” et la “polycristie”). Jusqu’à récemment, on ne connaissait rien sur la morphologie de leur dentition antérieure, mais des découvertes récentes réalisées en Grèce, au Kenya et en Namibie, lèvent le voile sur la morphologie de leurs incisives et de leur canine. Ainsi, il apparaît que les canines sont très dimorphes et que la dm/1 inférieure est remplacée par une p/1. Le matériel de Kipsaraman au Kenya, récolté entre 1997 et 2003, consiste en des fragments de mandibules et de nombreuses dents isolées, dont des dents déciduales, qui pour la plus grande part ne sont pas usées. Ces nouveaux fossiles confirment la nature aberrante de la dentition des sanithères au sein des Suoidea, et supporte leur classification dans une famille distincte des Suidae, et des Palaeochoeridae (= Tayassuidae de l’Ancien Monde).     

Tsuga shimokawaensis,a new species of permineralized conifer leaves from the Middle Miocene Shimokawa Group,Hokkaido, Japan

Silicified pinaceous leaves from the late Middle Miocene bed of Shimokawa Town, central Hokkaido, Japan are described asTsuga shimokawaensis sp. nov. Comparisons with leaves of extant species ofTsuga show that the new species is assigned to sect.Tsuga, resembling the extant speciesT. heterophylla in having usually one-cell-layered hypodermis, andT. sieboldii in having mesophyll cells between the resin canal and the hypodermis. From cladistic analyses we infer thatTsuga shimokawaensis is positioned the basal in sect.Tsuga and that sect.Tsuga comprises four species groups.