The first non‐marine ostracod fauna from the Lower Barremian dysodiles of Lebanon. (12th July 2020)

• Record Type: Journal Article
• Authors: El Hajj, Layla; Horne, David J.; Baudin, François; Gèze, Raymond; Azar, Dany
• Is Part Of: Lethaia. Volume 54:Number 1(2021)
• Page Start: 127
• Page End: 139
• Publication Date: 2020-07-12
• Subjects: Black shales -- Cretaceous -- lake -- micropaleontology -- palaeoenvironment -- taphonomy; Paleontology -- Periodicals; Geology, Stratigraphic -- Periodicals; 560
• DOI: 10.1111/let.12393
• Languages: English
• ISSNs: 0024-1164

Abstract

Abstract : Dysodiles are finely laminated sedimentary rocks rich in organic matter and in exceptionally well‐preserved fossils, hence their petroleum and palaeontological interest. However, few studies focused on the dysodiles of Lebanon, leaving their palaeontological content and their depositional environment largely unknown. Our previous investigations show a variety of well‐preserved lacustrine fossils including ichthyofauna, chelonians, insects, plant debris, gastropods, palynomorphs and ostracods. The present study focuses on the ostracods of five sampling localities from the Lower Barremian of Lebanon. Being the most abundant fossils, ostracods raise some taphonomic and palaeoecological questions that may help us understand the depositional environment and enrich the story of these Early Barremian lakes. Faunal differences between the sampled sections provide clues to the specific characteristics of each lake. The abundance of 'butterfly' preservation of carapaces, together with the association of adults and juveniles, indicates calm depositional environments without post‐mortem transport. The assemblages comprise ostracods with known swimming ability ( Cyprois and Zonocypris ) or that are thought to have been swimmers ( Cypridea ), while non‐swimmers are absent, suggesting that nektobenthonic ostracods must have lived only in the shallow margins of the lakes or among floating vegetation because hypolimnion conditions were hostile to benthos. This study provides different scenarios on how this fauna ended up preserved in the laminated lake sediments.