From Field to Lab : preparation of vertebrate fossils from a new Barremian Lagerstätte in South Lebanon

Lebanon is renowned for its rich Cenomanian fossil deposits, but recently its Lower Cretaceous deposits have also yielded significant fossils of plants, vertebrates and arthropods. In particular, the Barremian dysodiles (oil-shale mudstone) of Jdeidet Bkassine (Jezzine District, South Lebanon) are revealing vertebrate fossils of exceptional preservation. Until 2021, several surveys led to the discovery of ray-finned fishes, turtles and two complete mawsoniid coelacanths. In light of these promising finds, a two-week excavation was organised in 2023, supported by a National Geographic Society grant and involving an international team from Belgium, France, Lebanon, and Switzerland. The soft easily delaminated shales, allowed meticulous layer-by-layer investigation. A temporary preparation lab was set up on site to stabilise specimens, alongside identification and micro-sampling for geochemical analyses. This fieldwork unearthed an impressive array of vertebrates: coelacanths, an anura, pleurodiran turtles, squamates, and 5–7 different groups of actinopterygians. The most promising specimens were CT-scanned at the RBINS, offering invaluable insights for preparation and taxonomy. The introduction of an air abrasive unit using sodium bicarbonate and iron powder revolutionised the preparation workflow—dramatically improving speed and precision while preserving fine anatomical details, reducing the need for invasive tools like needles or airscribes. Many specimens remain to be prepared, some with exciting technical challenges. Yet the combination of exceptional preservation, with advanced 3D imaging, and refined preparation has allowed improving our understanding of macrosemiid and mawsoniid anatomy. We hope these finds could soon enough be on display in Lebanon, to share this remarkable Lagerstätte with the public.

EN, Abstract of an Oral Presentation or a Poster

Paleontology, Preparation, Fieldwork