Biostratigraphy and palaeoenvironments of the Upper Cretaceous fossil fish Konservat-Lagerstätten of Lebanon

Cenomanian deposits are well exposed in Lebanon and consist mainly of limestones that cover about 40% of the Lebanese territory. The sedimentary series is rich in fish fossils known from a distinct level in three outcrops dating from the Cenomanian: Haqel, Hjoula and Nammoura. These sites are known for the exceptional preservation of their fossil content. However, the stratigraphic assignment of the fossil-bearing level is controversial. We aim to address this controversy by measuring micropalaeontological samples we collected across facies outcropping at each of the three Konservat - Lagerstätten . The micropalaeontological inventory focusing on benthic and planktonic foraminifera identified at a family and a generic level and, where possible, at a specific level, is provided. Benthic foraminifers identified include Biokovinidae, Charentiidae, Cuneolinidae, Dicyclinidae, Mayncinidae, Nezzazatidae, Orbitolinidae, Spiroplectamminidae, Gavelinellidae, Alveolinoidea, Hauerinidae, Spiroloculinidae and other Miliolidae. Amongst the planktonic foraminifers, Hedbergellidae were identified (Globigerinelloididae, Heterohelicidae and Rotaliporidae). Additionally, several calcispheres were identified. Other biogenic components were identified, including rare dasycladalean algae, bryozoans, ostracods, echinoderms and bone debris. Overall, the microfossils indicate a middle Cenomanian age, based on the presence of Conicorbitolina conica and Favusella washitensis present within the Haqel and Hjoula Lagerstätten . The macrofossil assemblages consisting of echinoids and ammonites occurring above and/or below the Lagerstätten are surprisingly not in accordance with dating obtained by microfossils and give a late Cenomanian age for Haqel and Hjoula outcrops. In addition to the palaeontological studies, we conducted geochemical analyses to detect potential palaeoenvironmental signals. However, analysis of oxygen and carbon isotopes from the three outcrops did not recover any significant shifts across facies. Finally, an ichthyofauna inventory is compiled, based on data gathered from fieldwork and literature. The fish assemblage is unique, being the most speciose ever reported from the Mesozoic. The Haqel and Hjoula sites have approximately half of their species in common, while the Nammoura site has approximately 20% of its species in common with the other two localities. The comparison of the Lebanese fish faunas is discussed, as well as the origin of the Haqel and Hjoula assemblages. The geographically restricted sites of Haqel and Hjoula are tentatively interpreted as submerged sinkholes with favourable living conditions in the water column and with low-oxygen levels at the bottom that favoured the exceptional preservation of carcasses. The overlap of fish species across different beds representing distinct environments raises important palaeobiological and palaeoecological questions surrounding the Lebanese Lagerstätten .