Enamel thickness in the Middle Miocene great apes Anoiapithecus,Pierolapithecus and Dryopithecus

On the basis of industrial computed tomography, relative enamel thickness (RET) is computed in three Middle Miocene (ca 11.9–11.8 Ma) hominoids from Abocador de Can Mata (Vallès-Penedès Basin, Catalonia, Spain): Pierolapithecus catalaunicus from BCV1 and Anoiapithecus brevirostris from C3-Aj, interpreted as stem hominids; and Dryopithecus fontani from C3-Ae of uncertain phylogenetic affinities. Pierolapithecus displays an average RET value of 19.5, Anoiapithecus of 18.6 and Dryopithecus of 10.6. The thick-enamelled condition of Pierolapithecus and Anoiapithecus is also characteristic of afropithecids, including the more derived kenyapithecins from the early Middle Miocene of Eurasia (Griphopithecus and Kenyapithecus). Given the presence of other dentognathic and craniofacial similarities, thick enamel may be interpreted as a symplesiomorphy of the Hominidae (the great ape and human clade), which would have been later independently modified along several lineages. Given the correlation between thick enamel and hard-object feeding, our results suggest that thick enamel might have been the fundamental adaptation that enabled the out-of-Africa dispersal of great-ape ancestors and their subsequent initial radiation throughout Eurasia. The much thinner enamel of Dryopithecus is difficult to interpret given phylogenetic uncertainties, being either a hominine synapomorphy or a convergently developed feature.     

Ruminant diets and the Miocene extinction of European great apes

The successful evolutionary radiations of European hominoids and pliopithecoids came to an end during the Late Miocene. Using ruminant diets as environmental proxies, it becomes possible to detect variations in vegetation over time with the potential to explain fluctuations in primate diversity along a NW–SE European transect. Analysis shows that ruminants had diverse diets when primate diversity reached its peak, with more grazers in eastern Europe and more browsers farther west. After the drop in primate diversity, grazers accounted for a greater part of western and central European communities. Eastwards, the converse trend was evident with more browsing ruminants. These opposite trends indicate habitat loss and an increase in environmental uniformity that may have severely favoured the decline of primate diversity.     

The postcranium of Miocene hominoids: Were dryopithecines merely “dental apes”?

This paper reviews the non-dental morphological configuration of Miocene hominoids with special reference to the hypothesis of linear relationships between certain fossil species and living analogues. Metrical analysis of the wrist shows thatDryopithecus africanus andPliopithecus vindobonensis are unequivocally affiliated with the morphological pattern of quadrupedal monkeys. Similar analyses of the fossil hominoid elbow shows that they are more cercopithecoid-like than hominoid-like. Multivariate analysis of theP. vindobonensis shoulder in the matrix of extant Anthropoidea indicate that this putative hylobatine fossil shows no indication of even the initial development of hominoid features. The total morphological pattern of theD. africanus forelimb as assessed by principal coordinates analysis of allometrically adjusted shape variables has little resemblance toPan. Likewise, the feet and proximal femora of the Miocene fossils are unlike any living hominoid species. Even theD. africanus skull is similar to extant cercopithecoids in several features. Although ancestors cannot be expected to resemble descendants in every way, the striking dissimilarity between Miocene and extant hominoids seems to eliminate the consideration of a direct ancestor-descendant relationship between specific Miocene and modern forms.     

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.     

New palaeothentid marsupial from the Middle Miocene of Bolivia

The new species Acdestis maddeni is described based on the most complete skull of a palaeothentid marsupial known so far. The skull preserves most of the upper dentition and of the ear region, the latter an anatomical region previously unknown in this extinct family. A right maxillary fragment including C–M2 also belongs to the new species. The specimens come from the middle Miocene localities of Rosario and Quebrada Honda in southernmost Bolivia. The generic allocation of the new species is somewhat problematic, given that most of the taxonomy of fossil palaeothentids is based on lower dentitions. Compared to that of caenolestids, the skull of A. maddeni is much larger, with a shorter and broader snout, a proportionally narrower interorbital constriction, and a less globular, more triangular–shaped braincase in dorsal view.     

Diving ducks from the Middle Miocene of western Mongolia

Medium-sized diving ducks from the Middle Miocene of the Sharga locality (western Mongolia) are described. Sharganetta mongolica gen. et sp. nov. and Nogusunna conflictoides gen. et sp. nov. are evolutionary more advanced than the thoroughly studied Early Miocene genus Mionetta, but more primitive than Anatinae and Oxyurinae. The humeral morphology gives evidence of an aberrant position of the two new genera. Another taxon, Protomelanitta gracilis gen. et sp. nov. presumably belongs to basal Mergini.     

A new duck from the Middle Miocene of Mongolia, with comments on Miocene evolution of ducks

A new relatively large duck, Chenoanas deserta gen. et sp. nov. from the Middle Miocene of the Sharga locality, which is morphologically intermediate between the extant genera Chenonetta and Tachyeres, is described. The diversity of Early and Middle Miocene ducks is discussed. It is noted that some Middle Miocene duck remains are incorrectly referred to the genus Mionetta. The distribution of morphological characters of the humerus in Neogene and extant ducks shows that the present day diversity of ducks apparently results from extinction of some taxa which were formed in the Oligocene-Early Miocene. The distribution of morphological characters in the evolution of diving ducks is evidence that not only the formation of different morphotypes but also so-called ??evolutionary maturation?? of taxa also explains the modern diversity.     

Coral microbialite environment in a Middle Miocene reef of Hungary

The presence of microbial crusts (microbialites) is reported here for the first time from a Middle Miocene (Badenian) coral reef in Hungary. The succession of initiation and development of the microbial crusts is described in relation to the reef architecture. The main features of the palaeoenvironment are discussed, with focus on the associated invertebrate faunas, mostly corals, molluscs, bryozoans, and crabs. We conclude that the microbial crusts developed under normal marine conditions and were a significant contributor to reef framework development, including its strengthening through calcification of the microbial organisms. Microbialites are anticipated in other Early and Middle Miocene coral reef occurrences of the Mediterranean–Paratethys realm, and to date may have simply escaped positive recognition.     

On the Middle Miocene avifauna of Maboko Island,Kenya

The Middle Miocene sediments of Maboko Island (Lake Victoria) in western Kenya yielded numerous avian bones, which remained, however, little studied. The significance of this material is shown by the recent identification of an opisthocomiform bird. In the present study, further avian remains from Maboko Island are described. Most of the specimens belong to aquatic or semi-aquatic groups, of which some are closely related to taxa known from Early and Middle Miocene European avifaunas, that is, Nectornis cormorants (N. africanus nov. sp.) and Laricola-like Laromorphae. The fossil material also includes Ciconiidae (cf. Ciconia), Pelecanidae, Phoenicopteridae (Leakeyornis aethiopicus), Musophagidae, and a species of Ardeidae, which closely resembles the taxon Pikaihao from the Early Miocene of New Zealand. Some avian remains from Maboko Island belong to higher-level taxa unknown from the Middle Miocene of Europe. The occurrence of a giant Jacanidae (?Nupharanassa mabokoensis nov. sp.) is of particular interest, because these are globally absent in extant avifaunas and were previously only known from the Late Eocene/Early Oligocene of Egypt. Further unknown from contemporaneous European sites are small representatives of Jacanidae, Bucerotidae, and Alcedinidae, with the fossils of the latter two taxa being among the earliest published records of their respective groups. Several of the taxa that are common in contemporaneous European avifaunas have not been found in Maboko, and in spite of less pronounced climatic differences, Middle Miocene Afrotropical avifaunas already appear to have been distinct from contemporaneous European ones.     

Ctenodactylids from the Lower and Middle Miocene of Saudi Arabia

The ctenodactylids from the Lower and Middle Miocene of Saudi Arabia are represented by two species: Sayimys intermedius (Sen and Thomas, 1979) and Sayimys assarrarensis sp. nov. This new taxon differs from the other species of Sayimys by its larger size together with an association of characters such as the presence of a metalophulid II in d4 and the strength of the anteroloph and posteroloph in P4. A cladistic analysis involving Prosayimys flynni , Sayimys obliquidens , S. assarrarensis sp. nov., S. intermedius, S. sivalensis, S. baskini , and Metasayimys curvidens is provided. Sayimys assarrarensis sp. nov. nests between Sayimys obliquidens and Metasayimys curvidens as a relatively primitive taxon.     

New Middle Miocene Caviomorph Rodents from Quebrada Honda,Bolivia

The rodents of the middle Miocene fauna of Quebrada Honda Bolivia are described. The most abundant rodent is the chinchillid Prolagostomus sp. More precise identification of this species will require revision of early to middle Miocene lagostomines, taking into account variation in modern populations. The next most common rodents are the tiny octodontoid Acarechimys, sp. nov.?, and the caviid Guiomys unica. The Acarechimys species may be unique to Quebrada Honda, but verification awaits revision of this geographically and temporally widespread genus. Guiomys unica is a recently described species otherwise known only from two Patagonian localities, El Petiso and Río Chico. Two rodents are unique to Quebrada Honda. Mesoprocta hypsodus, gen. et sp. nov., is a dasyproctid distinguished by its very hypsodont, cement-covered cheek teeth. Quebradahondomys potosiensis, gen. et sp. nov., is an adelphomyine echimyid distinguished by the less oblique lophids of its trilophodont cheek teeth, among other features. The rodents of Quebrada Honda are more similar to those of Patagonia than those of northern South America, paralleling patterns seen in other mammal groups from this fauna.     

New fossil crocodilians from the Middle/Upper Miocene of Tunisia

New crocodilian material from the Beglia Formation (Middle/Upper Miocene) of Tunisia, although fragmentary, is reported. However, due to its fragmentary nature very little can be said about its affinities, and only the genus Euthecodon can be identified with certainty.     

Sarmatian (Late Middle Miocene) gastropod assemblages of the Central Paratethys

Summary A rather diverse gastropod fauna from Sarmatian deposits of the Austrian/Hungarian Eisenstadt-Sopron Basin was studied. The fauna derives from two layers of clay and silt within a siliciclastic section at St. Margarethen in Burgenland (Austria). These layers are interpreted as littoral mudflats which formed during the Sarmatian (Late Middle Miocene) along the western coast of the Central Paratethys. Strong shifts in the composition of the gastropod fauna, dominated by Potamididae (Cenogastropoda: Cerithioidea), within each layer indicate successions of limnic-fluvial to oligohaline, brackish-littoral, and marine-littoral environments. These shifts in facies are reflected by an alternational of thePotamides hartbergensis assemblage,Granulolabium bicinctum assemblage, and thePotamides disjunctus assemblage. The speciesJujubinus turriculus (Eichwald, 1850),Gibbula buchi (Dubois, 1831), andCylichnina elongata (Eichwald, 1830) are reported for the first time from the Sarmatian of the Paratethys.Mitrella agenta nov. sp. (Neogastropoda: Columbellidae) is introduced as a new species. These species might represent relics of the diverse Badenian fauna but could also prove a minor ingression of marine species from an adjacent bioprovince in the Late SarmatianMactra “Zone”.     

福建漳浦中中新世几种藓类植物研究*

亚洲新生代藓类植物化石非常稀少,漳浦琥珀是目前已知的我国低纬度地区唯一含苔藓植物化石的新生代琥珀矿床。漳浦琥珀源自中中新世气候适宜期(~14-17 Ma)的龙脑香树脂,温暖潮湿的热带季雨林气候和广泛分布的龙脑香科植物,为藓类植物的生长、多样性演化和三维立体保存提供了条件。本研究共报道了漳浦县中中新世藓类植物化石3个属种,包括:白发藓属Leucobryum Hampe、牛舌藓属Anomodon Hook.et Taylor和扁枝藓属Homalia(Brid.)B.S.G.。首次利用三维X射线断层扫描技术(Micro-CT)研究了白发藓属化石,发现其与现生种短枝白发藓Leucobryum humillimum Cardot非常相似,因此将其命名为短枝白发藓(相似种)Leucobryum cf.humillimum。此外,当前牛舌藓属Anomodon和扁枝藓属Homalia化石是东亚地区的首例记录。漳浦琥珀中的藓类植物化石揭示了中中新世时期苔藓植物的多样性,丰富了东亚低纬度地区新生代苔藓植物的化石记录。     

Finds of fragmentary bird skeletons in the Middle Miocene of the northern Caucasus

The first anatomically assembled skeletal remains of Neogene birds in Russia have been found. The head and a fragment of the vertebral column of a duck (Anatidae) and a hind limb of a perching bird (Passeriformes) from the Middle Miocene of the Krasnodar Region (Tsurevsky Formation) comprise the earliest known Miocene birds from European Russia. The skull of a very small duck (smaller than any extant species of Eurasian ducks) shows a combination of morphological characters characteristic of the extant species of Tadorna and Nettapus, and could belong to a representative of the fossil genus Mioquerquedula. This discovery supports a separate generic status for small-sized middle Miocene anatids from Eurasia, and suggests that they were more primitive than the extant Anatinae.     

Multiple dispersals and modern human origins

Despite a massive endeavour, the problem of modern human origins not only remains unresolved, but is usually reduced to “Out of Africa” versus multiregional evolution. Not all would agree, but evidence for a single recent origin is accumulating. Here, we want to go beyond this debate and explore within the “Out of Africa” framework an issue that has not been fully addressed: the mechanism by which modern human diversity has developed. We believe there is no clear rubicon of modern Homo sapiens, and that multiple dispersals occurred from a morphologically variable population in Africa. Pre-existing African diversity is thus crucial to the way human diversity developed outside Africa. The pattern of diversity—behavioural, linguistic, morphological and genetic—can be interpreted as the result of dispersals, colonisation, differentiation and subsequent dispersals overlaid on former population ranges. The first dispersals would have originated in Africa from where two different geographical routes were possible, one through Ethiopia/Arabia towards South Asia, and one through North Africa/Middle East towards Eurasia.     

Fossil leaves of Populus from the Middle Miocene of Yunnan,SW China

Today southern Yunnan, SW China, has a tropical or subtropical climate and seasonal rainforests. In the past, some temperate elements were also present. In this paper, a new species of Populus is reported from the Middle Miocene deposits in Zhenyuan. Its leaves are ovate or ovate-suborbicular, with serrate margins. They have a shallowly cordate to cuneate base without glands, short acuminate apex, and salicoid teeth with spherical glands. The veins are glabrous but unicellular hair bases occur on the lower epidermis of the lamina. Stomata are confined to the lower epidermis. The presence of Populus in the Middle Miocene of the region indicates an expansion of the genus into low-latitude Asia in the late Cenozoic and a more complicated history of vegetational change in southern Yunnan than has so far been assumed.