The antiquity of the Rhine River : stratigraphic coverage of the Dinotheriensande (Eppelsheim Formation) of the Mainz Basin (Germany)

Background: Mammalian fossils from the Eppelsheim Formation (Dinotheriensande) have been a benchmark for Neogene vertebrate palaeontology since 200 years. Worldwide famous sites like Eppelsheim serve as key localities for biochronologic, palaeobiologic, environmental, and mammal community studies. So far the formation is considered to be of early Late Miocene age (~9.5 Ma, Vallesian), representing the oldest sediments of the Rhine River. The stratigraphic unity of the formation and of its fossil content was disputed at times, but persists unresolved. Principal Findings: Here we investigate a new fossil sample from Sprendlingen, composed by over 300 mammalian specimens and silicified wood. The mammals comprise entirely Middle Miocene species, like cervids Dicrocerus elegans, Paradicrocerus elegantulus, and deinotheres Deinotherium bavaricum and D. levius. A stratigraphic evaluation of Miocene Central European deer and deinothere species proof the stratigraphic inhomogenity of the sample, and suggest late Middle Miocene (~12.5 Ma) reworking of early Middle Miocene (~15 Ma) sediments. This results agree with taxonomic and palaeoclimatic analysis of plant fossils from above and within the mammalian assemblage. Based on the new fossil sample and published data three biochronologic levels within the Dinotheriensand fauna can be differentiated, corresponding to early Middle Miocene (late Orleanian to early Astaracian), late Middle Miocene (late Astaracian), and early Late Miocene (Vallesian) ages. Conclusions/Significance: This study documents complex faunal mixing of classical Dinotheriensand fauna, covering at least six million years, during a time of low subsidence in the Mainz Basin and shifts back the origination of the Rhine River by some five million years. Our results have severe implications for biostratigraphy and palaeobiology of the Middle to Late Miocene. They suggest that turnover events may be obliterated and challenge the proposed ‘supersaturated’ biodiversity, caused by Middle Miocene superstites, of Vallesian ecosystems in Central Europe

Herbivorous large mammals from the late Middle Miocene Gratkorn locality (Styria, Austria) Taxonomy and Isotopic Tracking of Palaeoecology (δ18OCO3, δ13C, 87Sr/86Sr)

During transition from Middle to Late Miocene strong geographic, climatic, and biotic changes had a strong impact on aquatic and terrestrial ecosystems in Central Europe. Large-scale erosion in the Central Paratethys realm caused a lack of terrestrial sediments from this time period and thus resulted in a remarkable palaeobiological “blackout” for the record on land in this region from late Sarmatian to early Pannonian. The here presented Gratkorn locality, well dated to an age of 12.2/12.0 Ma (early late Sarmatian) provides a rich vertebrate assemblage (species diversity as well as total number of specimens) with 65 recorded species up to date. It represents a unique window to the terrestrial record of this time period and helps to understand the evolution of vertebrate faunas during the Middle-Late Miocene transition. Remains of herbivorous large mammals were morphologically described and assigned to the following taxa (Suidae not part of this thesis): Deinotherium levius vel giganteum, Aceratherium sp., Brachypotherium brachypus, Lartetotherium sansaniense, Chalicotherium goldfussi, Anchitherium sp., Listriodon splendens, Parachleuastochoerus steinheimensis, Dorcatherium naui, Micromeryx flourensianus, ?Hispanomeryx sp., Euprox furcatus, Palaeomerycidae gen. et sp. indet., and Tethytragus sp.. Except of Dorcatherium naui, presence and evolutionary stage of the large mammals are well in accordance with a late Middle Miocene assemblage. The records of Euprox furcatus and Micromeryx flourensianus comprise the first for the Styrian Basin and Hispanomeryx has not been recorded for Central Europe so far besides the locality Steinheim a. A.. Dorcatherium naui is considered a typical faunal element of the Late Miocene and has been described only recently from Middle Miocene localities. With the rich material from Gratkorn assignation of this species to a more selenodont phylogenetic lineage together with Dorcatherium guntianum and well distinct from Dorcatherium crassum can be verified and the descent of the species from the latter thus shown to be unlikely. The fossil assemblage from Gratkorn is considered an autochthonous taphocoenosis without any significant time averaging or faunal mixing. Most likely the accumulation did not last longer than a few years or decades and local accumulation of large mammal bones was the result of scavenging. Based on the taxonomic record, morphology of skeletal and dental elements, and especially isotope analyses (δ18OCO3, δ13C, 87Sr/86Sr), dominance of C3 vegetation, semi-arid and subtropical climate with distinct seasonality, and too little precipitation for closed canopy woodlands can be reconstructed for the wider area around the locality. The landscape provided diversity in plant resources to allow occupation of different niches by herbivorous large mammals: subcanopy browsing, rooting, top canopy browsing, facultative frugivory, and mixed feeding. Comparison with data from other Miocene localities from different areas and time slices showed rather stable niche partitioning for the herbivorous large mammal species. Thus these seem to be affected only to a minor degree by climatic conditions but rather represent a typical partitioning for a Middle Miocene ecosystem

Tragulidae and pecoran ruminants from the latest Middle Miocene (Sarmatian, late Astaracian) of Austria.

One of the richest and most complete European terrestrial vertebrate faunas of late Middle Miocene age (12.2¿12.0 Ma; Gross et al., in press) was found near Gratkorn, at the northeastern realm of the Styrian Basin (Austria). It is one of the rare localities from the Sarmatian sensu stricto (late Serravallian) in the Central Paratethys area with a vertebrate fauna, both high in quality as well as rich in quantity. So far, 62 taxa are recorded, including Euprox furcatus, Micromeryx flourensianus and Dorcatherium naui. This is one of the rare records of Dorcatherium naui older than Vallesian and the oldest finding of the species from the Paratethys realm so far. Up to now, Dorcatherium naui of pre-Vallesian ages have only been described from Przeworno (Poland; Glazek et al., 1971), and Abocador de Can Mata (Spain; Alba et al., 2011), which are of latest Middle Miocene age like Gratkorn. Therefore the latter does not only represent one of the oldest records of Dorcatherium naui but also supports the wide distribution of the taxon already at the latest Middle Miocene. In contrast to the site of Abocador de Can Mata, where Dorcatherium naui is an infrequent element (Alba et al., 2011), the species is abundant at the locality of Gratkorn. Apart from this the larger mammal fauna of Abocadar de Can Mata and Gratkorn is quite similar, except of proboscidean and bovid taxa. While in Abocador de Can Mata Gomphotherium, Deinotherium and bovids are present (Alba et al., 2009), in Gratkorn only Deinotherium giganteum was found until now. Bovids were found in contemporaneous sediments in the eastern Styrian Basin (Gross et al., in press), though. With the material of Gratkorn previous ideas on ecological adaptations in Dorcatherium (Rössner, 2004) are supported and the understanding of the ecological niche of the ¿forest-dweller¿ Dorcatherium is specified. Besides new ideas on dispersal, evolution and ecology of Dorcatherium the locality of Gratkorn also enables an in-depth evaluation of its species separation. The specimens from Gratkorn demonstrate, in comparison with other Material from the Paratethys area, a clear distinction between Dorcatherium crassum and Dorcatherium naui and underline the taxonomic separation of both species as accepted by several authors (e.g. Alba et al., 2011). REFERENCES Alba, D.M. et al. (2009). Middle Miocene vertebrate localities from Abocador de Can Mata (els Hostalets de Pierola, Vallès Penedès Basin, Catalonia, Spain): An update after the 2006-2008 field campaigns. Paleolusitana, 1, 59¿73. Alba, D.M. et al. (2011). Middle Miocene tragulid remains from Abocador de Can Mata: the earliest record of Dorcatherium naui from Western Europe. Geobios, 44, 135-150. Glazek, J. et al. (1971). Miocene vertebrate faunas from Przeworno (Lower Silesia) and their geological setting. Acta Geologica Polonica, 21(3), 473-516. Gross, M. et al. (in press). Gratkorn ¿ A benchmark locality for the continental Sarmatian s. str. of the Central Paratethys. International Journal of Earth Sciences, doi: 10.1007/s00531-010-0615-1. Rössner, G.E. (2004). Community structure and regional patterns in late Early to Middle Miocene Ruminantia of Central Europe. Courier Forschungs-Institut Senckenberg, 249: 91-100.Peer Reviewe

Na Duong (northern Vietnam) – an exceptional window into Eocene ecosystems from Southeast Asia

Today, the continental ecosystems of Southeast Asia represent a global biodiversity hotspot. From a deep-time perspective, however, very little is known about the formation of this hotspot. In particular, the evolutionary and biogeographic roots of numerous terrestrial biota are unknown, and ecosystemic information, especially for the Paleogene, is unavailable. The Na Duong Basin in northern Vietnam has yielded a remarkable diversity of Paleogene vertebrate, invertebrate, and plant fossils, and is thus one of the few localities in Southeast Asia allowing for multi-focused investigation of this period. We present stratigraphic, paleontologic, and paleoecologic results from the 220 m thick Na Duong section derived from magnetostratigraphy, biochronology, vertebrate, invertebrate, and plant taxonomy, and biomarker analysis. Only the upper 40 m of the section show the original magnetization, prohibiting any further magnetostratigraphic interpretation. The affinities of two newly described mammal species, Bakalovia orientalis nov. sp. (Anthracotheriidae) and Epiaceratherium naduongense nov. sp. (Rhinocerotidae), suggest an Eocene, late Bartonian to Priabonian age (39–35 Ma). High biodiversity is recorded for unionid mussels (five species), freshwater fishes (nine taxa, including Planktophaga minuta nov. gen. et sp.), turtles (five to six taxa), and crocodiles (three taxa), and long-term stability of Southeast Asian unionid and fish faunas is demonstrated. Fossil leaves, wood and resin document azonal and zonal vegetation; dipterocarp trees were identified from resin exudate spectroscopy. In-situ tree-stump horizons allow for calculation of tree density (600 specimens/ha) and maximum canopy height (35m); both values resemble those of recent Southeast Asian peat swamp forests. Environment changed abruptly from a swamp forest to a tropical to warm sub-tropical lake of fluctuating water depth. The strong biogeographic link between the Eocene mammal faunas from Na Duong and Europe highlights the importance of Southeast Asia as a source region for trans-continental mammal dispersal along the northern Tethys margin.Heutige kontinentale Ökosysteme Südost Asiens sind ein Hotspot der globalen Biodiversität, über dessen geohistorische Entstehung jedoch sehr wenig bekannt ist. So sind die evolutionären und biogeographischen Wurzeln der meisten terrestrischen Lebensformen unbekannt und Daten zu Ökosystemen, speziell aus dem Paläogen, fehlen. Das Becken von Na Duong im nördlichen Vietnam beherbergt bemerkenswert diverse Biota fossiler Pflanzen, Mollusken und Wirbeltiere und stellt für das Paläogen eine der wenigen Regionen Südost Asiens dar, welche einen multi-disziplinären Untersuchungsansatz erlauben. Auf der Grundlage von Paläomagnetik, Biochronologie, Wirbeltier-, Mollusken- und Pflanzen-Taxonomie, sowie der Analyse von Biomarkern präsentieren wir hier unsere stratigraphischen, paläontologischen und paläo-ökologischen Ergebnisse eines 220 m mächtigen Profils der Braunkohlengrube Na Duong. Nur die hangenden 40 m der Sektion zeigen die ursprüngliche Magnetisierung, wodurch eine magnetostratigraphische Interpretation verhindert wird. Die Verwandschaftsverhältnisse von zwei neu beschriebenen Säugetierarten, Bakalovia orientalis nov. sp. (Anthracotheriidae) und Epiaceratherium naduongense nov. sp. (Rhinocerotidae), verweisen auf ein eozänes Alter (oberes Bartonium bis Priabonium, 39-35 Ma). Starke biogeographische Bezüge beider Säugetiere aus Na Duong zu europäischen Arten unterstreichen die Bedeutung Südost Asiens als eine Quellregion paläogener transkontinentaler Säugetier Ausbreitungen entlang des nördlichen Randes der Tethys. Hohe Diversitäten werden für unionide Muscheln (fünf Arten), Süßwasserfische (9 Taxa, darunter Planktophaga minuta nov. gen. et sp.), Schildkröten (fünf bis sechs Taxa) und Krokodile (drei Taxa) belegt, wobei eine taxonomische Langzeit-Stabilität der Unioniden- und Fisch-Faunen Südost Asiens belegt wird. Fossile Blätter, Hölzer und Harze dokumentieren die azonale und zonale Vegetation, letztere repräsentiert durch spektroskopisch an Harzen belegte Zweiflügelfrucht-Gewächse (Dipterocarpaceae). In-situ Baumstubben-Horizonte erlauben die Berechnung der Baum-Dichte (600 per ha) und der maximalen Kronendach-Höhe (35 m), welches in guter Übereinstimmung zu heutigen südostasiatischen Sumpfwäldern steht. Die Umwelt veränderte sich abrupt von einem Sumpfwald zu einem tropisch bis warm-subtropischen See mit fluktuierender Wassertiefe

Cutting the Gordian knot: a historical and taxonomic revision of the Jurassic crocodylomorph Metriorhynchus

Figure 3. Metriorhynchus brevirostris holotype MHNG V-2232. A, anterior view; B, posterior view. See text for anatomical abbreviations.Published as part of Young, Mark T., Brignon, Arnaud, Sachs, Sven, Hornung, Jahn J., Foffa, Davide, Kitson, James J. N., Johnson, Michela M. & Steel, Lorna, 2021, Cutting the Gordian knot: a historical and taxonomic revision of the Jurassic crocodylomorph Metriorhynchus, pp. 510-553 in Zoological Journal of the Linnean Society 192 (2) on page 535, DOI: 10.1093/zoolinnean/zlaa092, http://zenodo.org/record/701700

Ruminantia from the middle Miocene of the Gracanica coalmine (Bugojno Basin, Bosnia-Herzegovina)

Five different ruminant taxa were found in the Gracanica coal mine: the tragulid Dorcatherium vindebonense, a palaeomerycid (Palaeomerycidae gen. et sp. indet.), the giraffe Giraffokeryx sp., and the bovids ?Tethytragus sp. and Eotragus ?clavatus. The ruminant fauna fits well to an early middle to middle middle Miocene age and is typical for a locality of the mammal units MN5 or MN6. The assemblage shows Asian as well as European affinities, represents the westernmost occurrence of Giraffokeryx known so far, and confirms the role of the Balkan Peninsula as a corridor between the two continents. As the ruminant assemblage from Gracanica is not abundant, palaeoecological considerations are only tentative, but the determined taxa point to a predominantly forested environment. © 2018, Senckenberg Gesellschaft für Naturforschung and Springer-Verlag GmbH Germany, part of Springer Nature