Carbon and oxygen stable isotope compositions of late Pleistocene mammal teeth from dolines of Ajoie (Northwestern Switzerland)

International audienceFossils of megaherbivores from eight late Pleistocene 14C- and OSL-dated doline infillings of Ajoie (NW Switzerland) were discovered along the Transjurane highway in the Swiss Jura. Carbon and oxygen analyses of enamel were performed on forty-six teeth of large mammals (Equus germanicus, Mammuthus primigenius, Coelodonta antiquitatis, and Bison priscus), coming from one doline in Boncourt (~ 80 ka, marine oxygen isotope stage MIS5a) and seven in Courtedoux (51–27 ka, late MIS3), in order to reconstruct the paleoclimatic and paleoenvironmental conditions of the region. Similar enamel δ13C values for both periods, ranging from − 14.5 to − 9.2‰, indicate that the megaherbivores lived in a C3 plant-dominated environment. Enamel δ18OPO4 values range from 10.9 to 16.3‰ with a mean of 13.5 ± 1.0‰ (n = 46). Mean air temperatures (MATs) were inferred using species-specific δ18OPO4–δ18OH2O-calibrations for modern mammals and a present-day precipitation δ18OH2O-MAT relation for Switzerland. Similar average MATs of 6.6 ± 3.6°C for the deposits dated to ~ 80 ka and 6.5 ± 3.3°C for those dated to the interval 51–27 ka were estimated. This suggests that these mammals in the Ajoie area lived in mild periods of the late Pleistocene with MATs only about 2.5°C lower than modern-day temperatures

To split or not to split Anthracotherium? A phylogeny of Anthracotheriinae (Cetartiodactyla: Hippopotamoidea) and its palaeobiogeographical implications

Since its first erection almost 200 years ago, palaeontologists have assigned to the genus Anthracotherium many species, some with dubious descriptions. Although it is a key taxon for specifying the invasion of Europe by terrestrial mammals during the well-studied Grande Coupure Event at the beginning of the Oligocene, the genus has never been reviewed before. A recent interest in the relationships of anthracotheres and hippopotamids highlighted its importance for the understanding of diversity of anthracotheres. Herein, we conduct a systematic review of most European anthracotheriine species, including some Asian and American species in order to establish a more exhaustive anthracotheriine phylogeny. A cladistic analysis focusing on anthracotheriines supports us in redefining and clarifying the systematic status of most genera and species of this subfamily. Furthermore, our study results in the division of Anthracotherium into two different genera, the definition of a new taxon, Paenanthracotherium gen. nov., and the creation of a new species from previously described material, Paenanthracotherium bergeri sp. nov. Additionally, our phylogeny suggests a new palaeogeographical scenario implying several dispersal events from Asia to Europe before and during the Grande Coupure Event. This study marks the first step to a much-needed global review of anthracotheriines, including the American and Asian specimens

Tapiridae (Perissodactyla, Mammalia) of the Swiss Molasse Basin during the Oligocene-Miocene transition

The Tapiridae of the Swiss Molasse Basin from the late Oligocene to the early Miocene are reviewed. Fossil remains that have not previously been described are identified, old descriptions and identifications from previous works are reassessed, and specimens from Switzerland and France are compared, specifically Protapirus bavaricus from Ebnat-Kappel (MP28) and Rüfi bei Schänis (MP29), Protapirus aginensis from La Milloque (France, MP29), Protapirus douvillei from Buchberg 6 (MN4), Paratapirus helvetius from Haslen (Switzerland, MP28-30), Paratapirus intermedius from Saulcet (France, MN1), Höhronen (MN1), and Brüttelen 1 (MN3a), and Eotapirus broennimanni from Wischberg (MN1) and Benken (MN3-4?). These new data enable emended specific diagnoses for Protapirus bavaricus, P. aginensis, and P. douvillei. A late Oligocene (MP28-30) age for the locality of Haslen—the neotype locality of Paratapirus helvetius—is also attributed, based upon the literature and personal observations. Furthermore, a new and precise biostratigraphic range of the European Tapiridae at the species level is proposed for the Oligocene and early Miocene of Western Europe. The paleoecology of tapirs and their diversity and evolution through the Oligocene-Miocene transition are discussed and compared with contemporaneous large mammals such as Rhinocerotoidea, Anthracotheriidae, and Suoidea

Evolutionary history of hoofed mammals during the Oligocene–Miocene transition in Western Europe

The biostratigraphy and diversity patterns of terrestrial, hoofed mammals help to understand the transition between the Palaeogene and the Neogene in Western Europe. Three phases are highlighted: (1) the beginning of the Arvernian (Late Oligocene, MP25-27) was characterised by a “stable” faunal composition including the last occurrences of taxa inherited from the Grande Coupure and of newly emerged ones; (2) the latest Arvernian (Late Oligocene, MP28-30) and the Agenian (Early Miocene, MN1-2) saw gradual immigrations leading to progressive replacement of the Arvernian, hoofed mammals towards the establishment of the “classical” Agenian fauna; (3) the beginning of the Orleanian (Early Miocene, MN3-4) coincided with the African-Eurasian faunal interchanges of the Proboscidean Datum Events and led to complete renewal of the Agenian taxa and total disappearance of the last Oligocene survivors. Faunal balances, poly-cohorts and particularly cluster analyses emphasise these three periods and define a temporally well-framed Oligocene–Miocene transition between MP28 and MN2. This transition started in MP28 with a major immigration event, linked to the arrival in Europe of new ungulate taxa, notably a stem group of “Eupecora” and the small anthracothere Microbunodon. Due to its high significance in the reorganisation of European, hoofed-mammal communities, we propose to name it the Microbunodon Event. This first step was followed by a phase of extinctions (MP29-30) and later by a phase of regional speciation and diversification (MN1-2). The Oligocene–Miocene faunal transition ended right before the two-phased turnover linked to the Proboscidean Datum Events (MN3-4). Locomotion types of rhinocerotids and ruminants provide new data on the evolution of environments during the Oligocene–Miocene transition and help understand the factors controlling these different phases. Indeed, it appears that the faunal turnovers were primarily directed by migrations, whereas the Agenian transitional phase mainly witnessed speciations

Large mammals from Rickenbach (Switzerland, reference locality MP29, Late Oligocene): biostratigraphic and palaeoenvironmental implications

Since the first exploitation of the Huppersandstones quarry of Rickenbach (Canton Solothurn, Switzerland) in 1898, many fossils of plants, molluscs, and vertebrates have been discovered. The study of the small mammals brought this locality to international recognition as the type locality for the European mammalian reference level MP29 (latest Oligocene). Our study reviews the terrestrial herbivorous mammals of Rickenbach and aims to reconstruct the palaeoenvironmental and palaeoclimatic conditions in which they lived. The perissodactyls and cetartiodactyls are described and identified: Protapirus sp. (Tapiridae), Ronzotherium romani and Diaceratherium lamilloquense (Rhinocerotidae), Anthracotherium magnum and Microbunodon minimum (Anthracotheriidae), Palaeochoerus pusillus (Suoidea), and Dremotherium guthi, “Amphitragulus” quercyi, “Amphitragulus” feningrei, and Babameryx engesseri gen. et sp. nov. (Ruminantia). Based on the updated faunal list, a cenogram of the locality of Rickenbach is established. We also performed ecomorphologic analyses on ruminants and rhinocerotids. The reconstructed palaeoenvironment of Rickenbach probably corresponded to a savannah woodland affected by a subtropical climate with clear seasonality

New skeleton from the early Oligocene of Germany indicates a stem-group position of diomedeoidid birds

We report a new specimen of the extinct procellariiform species Diomedeoides brodkorbi (Aves, Diomedeoididae) from the early Oligocene (Rupelian) of Rheinweiler in southwestern Germany. The well−preserved partial skeleton allows the recognition and reassessment of new osteological details that bear on the phylogenetic affinities of diomedeoidids. The presence on the coracoid of a deeply excavated, cup−like facies articularis for the scapula suggests a stem group position of the Diomedeoididae within Procellariiformes, because this trait also occurs in stem−group representatives of several avian groups, as well as in Mesozoic non−neornithine birds, and is a plesiomorphic character. We hypothesize that the similarities of Diomedeoides to extant southern storm−petrels (Oceanitinae), such as the long mandibular symphysis, the small processus supracondylaris dorsalis and the long legs are plesiomorphic for Procellariiformes