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Although a high number of extant beaked whale species (Cetacea, Odontoceti, Ziphiidae) live in the Southern Ocean and neighbouring areas, only little is known about the past occupation of the region by these highly specialized, deep diving and echolocating cetaceans. Recently, longline fishing activities along the seafloor at depths of 500–2000 m off the sub-antarctic Crozet and Kerguelen islands, Indian sector of Southern Ocean, resulted in the accessory “capture” of tens of ziphiid fossil cranial remains. Our description and comparison of the best-preserved and most diagnostic crania from this sample lead to the identification of more than eight species in at least seven genera: the hyperoodontines Africanacetus ceratopsis, Khoikhoicetus kergueleni n. sp., Hyperoodontinae indet. aff. Africanacetus, and Mesoplodon sp. aff. Mesoplodon layardii, the ziphiines Izikoziphius rossi and Ziphius sp., and the ziphiids indet. Nenga sp. aff. Nenga meganasalis and Xhosacetus hendeysi.
Unsurprisingly, with at least four species in common (A. ceratopsis, Izikoziphius rossi, X. hendeysi, and Ziphius sp.), the assemblage displays high similarities with assemblages described from deep-sea deposits off South Africa, providing thus new data on the palaeogeographic distribution of several extinct species and indicating a roughly similar geochronological age for at least a part of the assemblages. The limited amount of data available points to a pre-Pliocene age for a large part of the Crozet-Kerguelen assemblage, suggesting a relatively early, Miocene colonization of the Southern Ocean by crown ziphiids. Contrastingly, 14C radiometric dating of two specimens of Mesoplodon sp. aff. Mesoplodon layardii yielded latest Pleistocene-earliest Holocene ages. These results reveal the presence either of an extinct species of Mesoplodon in the Southern Ocean only a few thousands years ago, or of an up-to-now unidentified extant species closely related to the strap-toothed whale M. layardii.
The first tuna-shaped amniotes evolved among ichthyosaurs, but this group exhibits in fact a wide diversity of morphologies and swimming modes. The histology and microanatomical features of vertebral centra of a diversity of ichthyosaur taxa from most basal to highly derived illustrating this variability were analyzed. The occurrence of unusual parallel fibered bone with platings of true parallel-fibered bone confirms high growth rate in all these taxa. Ichthyosaur vertebrae, which are deeply amphicoelous, show a limited endosteal territory associated with a limited growth in length. No bone mass increase nor decrease occurs. The vertebral centrum is spongious, and two microtypes are observed in the periosteal territory, with different degrees of organization of the trabecular network. The microtypes appear to be associated with the shape of the vertebral centrum, the organization of the spongiosa becoming homogeneous in the disk-shaped centra of cymbospondylids and Neoichthyosauria, rather than much more heterogeneous in spool-shaped centra of primitive Triassic forms. As opposed to what was previously suggested in other amniotes, the main switch in microanatomical organization appears thus to be correlated to the acquisition of deeply amphicoelous disk-like vertebral centra rather than to a shift in swimming mode from long and slender-bodied anguilliform swimmers to thunniform swimmers.
L'étude biométrique des équidés du lac Karâr (composés exclusivement de matériel dentaire) montre qu'ils appartiennent (en majorité) très probablement à l'âne sauvage fossile (Equus africanus Heuglin & Fitzinger, 1866) contrairement à l'étude descriptive de Boule (1900) qui les a attribué en totalité à l'espèce fossile et zébrine Equus mauritanicusPomel, 1897 et comme évoqué dans le travail synthétique de Churcher & Richardson (1978). Ce travail remet d'actualité la question toujours mal connue de la date et du lieu d'apparition des ânes en Afrique. En effet, en Afrique du Nord-Ouest (Maghreb) tout du moins, la plupart des ânes fossiles identifiés comme tels et connus sous le nom de l'âne de l'Atlas (Equus atlanticus Thomas, 1884 ; Equus melkiensisBagtache, Hadjouis & Eisenmann, 1984) proviennent de sites datant du Pléistocène supérieur ou de périodes plus récentes (Romer 1928, 1935; Churcher & Richardson 1978; Bagtache & Hadjouis 1983; Bagtache et al. 1984; Eisenmann 1986, 1995; Zouhri et al. 1997) tandis que le lac Karâr est l'un des rares gisements potentiellement du Pléistocène moyen à avoir livré suffisamment de restes dentaires pouvant appartenir à cette espèce, d'où l'importance d'une étude biomoléculaire et d'une datation radioactive de ce matériel. L'équidé du lac Karâr pourrait donc être le représentant asinien du Pléistocène moyen qui manquait jusqu'ici sachant que le Pléistocène inférieur est symbolisé par Equus tabetiArambourg, 1970, espèce dont le statut spécifique, quoique relativement ambigu (Arambourg, 1970), pourrait avoir des relations phylogénétiques avec l'âne de l'atlas (Hadjouis & Le Bihan 2013). Enfin, la présence dans l'échantillon de l'espèce zèbrine Equus mauritanicus n'est certainement possible que pour deux molaires inférieures intermédiaires.
Polychelidan lobsters (Crustacea: Decapoda) are abundant in the celebrated Middle Jurassic (Callovian) Lagerstätte of La Voulte-sur-Rhône (Ardèche, France). Among them, Eryon giganteusVan Straelen, 1923, is recognized by its large, rounded carapace. The generic assignment of this species has been particularly complicated, with many conflicting assignments proposed since the first description of the species. The present study reinvestigates E. giganteus following the rediscovery of its lectotype. Careful examinations reveal that the type material is composite: the lectotype belongs to a species of eryonid that was described recently as Cycleryon romani Audo, Schweigert, Saint Martin & Charbonnier, 2014, and is quite rare (six specimens); the rest of the material, and most specimens formerly assigned to E. giganteus correspond to an abundant species of ProeryonBeurlen, 1928 (33 specimens) that we herein describe as Proeryon charbonnieri n. sp. The present study also allows us to reinvestigate the generic assignment of E. giganteus. Detailed observations allowed assigning E. giganteus to Soleryon Audo, Charbonnier, Schweigert & Saint Martin, 2014 based upon: the grooves marked across the dorsal part of carapace; a posterior carina near the posterior margin; and a hepatic carina between cervical and hepatic grooves. This taxonomic revision also leads to abandon Proeryon zehentbaueri, the replacement name which was proposed for Proeryon giganteusBeurlen, 1930.
Neogene lacustrine deposits in Zahle, western margin of the Bekaa Valley (Lebanon), are studied from a biostratigraphic and paleoenvironmental point of view using fossil charophytes. These sediments contain a well-preserved charophyte assemblage described and illustrated here for the first time including the taxa: Nitellopsis (Tectochara) merianiiGrambast & Soulié-Märsche, 1972, Lychnothamnus barbatus var. antiquusSoulié-Märsche, 1989, Chara aff. microceraGrambast & Paul, 1965 and Chara sp. Nitellopsis (T.) merianii has been reported in several European and Asiatic localities ranging in age from Late Eocene to Pliocene, L. barbatus var. antiquus has been found in several European Miocene localities in Europe and Turkey, while Chara aff. microcera has been documented from a large number of west European localities ranging in age from Early Oligocene to Early Miocene. Based on these data, we inferred that the basal part of the lacustrine deposits of Zahle is lower Miocene in age which is consistent with isotopic results obtained from basalts located northern, laterally and above the lacustrine sequence of Zahle. The palaeoenvironmental characteristics at the base of these deposits are inferred by comparing of the occurrence of N. (T.) merianii and L. barbatus var. antiquus with the ecological requirements of their nearest living relatives (Nitellopsis obtusa and Lychnothamnus barbatus). This suggests that the Bekaa Valley was occupied by a permanent, shallow oligotrophic freshwater lake during the Miocene. This study also provides valuable data about the palaeogeographic distribution of Neogene charophyte from Lebanon and the Middle East region.
Gastropods and bivalve associations from the middle and ?upper Eocene (Bartonian and ?Priabonian) sedimentary succession of the Pamplona Basin are described. This succession was accumulated in the western part of the South Pyrenean peripheral foreland basin and extends from deep marine turbiditic (Ezkaba Sandstone Formation) to deltaic (Pamplona Marl, Ardanatz Sandstone and Ilundain Marl formations) and marginal marine deposits (Gendulain Formation). Fossils are generally fragmentary and many correspond to remains that have undergone taphonomic reworking. Significant effects of diagenesis are also detected, with evidence of compression or deformation, dissolution, aragonite-calcite neomorfism and cementation by celestite. Bioerosion traces and fossil encrusters are common. Fossils of 37 taxa, 25 gastropods and 12 bivalves, have been identified confidently. The number of species is probably considerably higher, as the study of some fossils, mainly the most small-sized species, is pending. One new species, Athleta (Volutospina) delvallei Astibia, Merle & Pacaud, n. sp. (Gastropoda, Volutidae), is described herein. Fossil assemblages are comparable to those from the Eocene of the Basque Coast (North Pyrenean area) and Aragon and Catalonia (west-central and eastern part of South Pyrenean area). Most of the mollusc taxa seem to be endemic to the Pyrenean area, but several Tethyan and Northern elements have also been recorded. These results enlarge the database for a better understanding of the evolution of global marine biodiversity throughout the Eocene.
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