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

Allaeochelys libyca, a new carettochelyine turtle from the middle miocene (Langhian) of Libya

Fossil carettochelyine turtles are well known from the Paleogene of Europe (Allaeochelys), North America and Asia (Anosteira); however, the previously known Neogene fossil record is highly fragmentary and was therefore unsuitable for taxonomic analysis. In this work, we present a new carettochelyine taxon, Allaeochelys libyca, from the Middle Miocene (Langhian) of Gebel Zelten (Libya) based on an incomplete skull and disarticulated postcranial elements. The new taxon is diagnosed relative to the extant Carettochelys insculpta based on the placement of the foramen posterius canalis carotici interni close to the fenestra postotica, the horizontal orientation of the tubercula basioccipitalis, the substantial contribution of the opisthotic to the base of the tubercula basioccipitalis, the presence of a triangular pterygoid fossa, the arrangement of the mandibular condyles along a plane and the presence of an extremely well-developed fossa at the base of the processus mandibularis. A phylogenetic analysis of pancarettochelyids confirms the monophyly of Carettochelyidae and Carettochelyinae but resulted in a paraphyletic taxon, Allaeochelys. For the sake of nomenclatural stability, we provisionally retain the genus Allaeochelys as paraphyletic relative to the extant Carettochelys insculpta

Edmonds prehistoric realm: A dino-excavation in Frankfurt

Das Projekt „Edmonds Urzeitreich“ ist eine bisher einzigartige Verbindung aus Museumsarbeit, Grabung und Forschung.Ein Dinosaurier-Bonebed wurde in Zusammenarbeit mit Bürgerwissenschaftler/-innen aus den USA nachFrankfurt verschifft und wird nun im Senckenberg Naturmuseum Frankfurt vor den Augen der Besucher/-innen ausgegraben. Parallel dazu erforscht ein Team aus Geowissenschaftler/-innen das ganze Ökosystem rund um den Fund, von den Pollen bis hin zur Nahrungsweise von Tyrannosaurus rex. Hierbei entsteht ein lebendiges und detailliertes Bild eines Ökosystems vor 70 Millionen Jahren – einer Zeit, in der die CO2-Konzentration in der Erdatmosphäre deutlich höherwar als heutzutage.The project “Edmonds prehistoric realm” is a so far unique combination of exhibition, excavation and research. A dinosaur bonebed was shipped from the USA to Frankfurt in collaboration with citizen scientists and is now being excavated in front of the visitors in the Senckenberg Natural History Museum Frankfurt. At the same time, a team of geoscientists is analysing the entire ecosystem surrounding the findings, from pollen to the diet of Tyrannosaurus rex. This offers the chance to create a vivid and detailed reconstruction of an ecosystem 70 million years ago – a time when the CO2 concentration in the Earth’s atmosphere was significantly higher than today

Re-description of 'Steneosaurus' obtusidens Andrews, 1909, an unusual macrophagous teleosaurid crocodylomorph from the Middle Jurassic of England

Teleosaurids were a clade of crocodylomorphs that attained near-global distribution during the Jurassic Period. Within Teleosauridae, one particular sub-clade of durophagous/macrophagous taxa achieved large body sizes and were apex predators in shallow marine environments during the Late Jurassic and Early Cretaceous in Europe and around the coast of the Tethys Seaway. Unfortunately, the origins of this clade are still poorly understood. 'Steneosaurus' obtusidens is a little-studied macrophagous species from the Oxford Clay Formation (Callovian, Middle Jurassic) of the UK and near Migné-les-Lourdines (Middle Callovian) in France. Despite being considered a sister taxon of the Late Jurassic taxon Machimosaurus, the taxonomy of 'S.' obtusidens remains unclear. Although three different synonymies have been proposed (variously a subjective synonym of other taxa), these taxonomic hypotheses have not been based on detailed anatomical comparisons and thus have not been tested. Here, we re-describe the holotype of 'S.' obtusidens, demonstrate that it is indeed a valid taxon, restrict the referred specimens to a fragmentary skeleton, nearly complete skull, and partial rostrum, and establish a new monotypic genus, Lemmysuchus. Our re-description reveals five autapomorphies for Lemmysuchus obtusidens and nine apomorphic characters that support the tribe Machimosaurini (Lemmysuchus + Machimosaurus).</p

Addendum to ‘Revision of the Late Jurassic teleosaurid genus Machimosaurus (Crocodylomorpha, Thalattosuchia)’

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