Une remarquable association d’otolithes de poissons dans le Miocène moyen de Sos, Matilon (France, Lot-et-Garonne).A remarkable assemblage of fish otoliths from the Middle Miocene of Sos, Matilon (France, Lot-et-Garonne)
Nolf, D.; Cahuzac, B. (2009). Une remarquable association d’otolithes de poissons dans le Miocène moyen de Sos, Matilon (France, Lot-et-Garonne).A remarkable assemblage of fish otoliths from the Middle Miocene of Sos, Matilon (France, Lot-et-Garonne). Bull. Kon. Belg. Inst. Natuurwet. Aardwet. = Bull. - Inst. r. sci. nat. Belg., Sci. Terre 79: 191-204
In: Bulletin van het Koninklijk Belgisch Instituut voor Natuurwetenschappen. Aardwetenschappen = Bulletin de l'Institut Royal des Sciences Naturelles de Belgique. Sciences de la Terre. KBIN: Brussel. ISSN 0374-6291
The Serravallian site of Sos (Matilon, base of the section) is located near to the shore of the gulf of eastern Aquitaine. The studied sediment is a near shore coquina facies with a well-preserved and diversified marine fauna, reflecting a bay environment, with some brackish influences. Otoliths of 22 teleost taxa were identified, two of them representing new species: Afroscion rezeaui and “genus aff. Afroscion” carinatus. The association is characterised by a strong dominance of sciaenids (83% of the total number of otoliths). Among the remaining taxa, Pomadasys aff. incisus and a Gobius (elongate form) account for respectively 3% and 12%; all remaining taxa are rare. Except for the Serravallian coquinas of Orthez and Sallespisse, sciaenid otoliths are very rare in all Oligo-Miocene sampling sites of Aquitaine. Sciaenids from Sos, where Afroscion rezeaui and Sciaena irregularis dominate, are different from those of Orthez and Sallespisse, dominated by Umbrina pyrenaica. Only Argyrosomus regius is common to both associations. In total, only seven species are common to the two localities, and the sparid Dentex aff. maroccanus is lacking at Sos. The two faunas seem to correspond to quite different environments. Sciaenids are quite tolerant for fresh water, and the Sos area could be near to a stream mouth at the end of the gulf. Some sciaenids are even partly freshwater fishes. At Orthez – Sallespisse, the represented sciaenids are very near shore forms, but of normal salinity: this is attested by the frequence of Dentex aff. maroccanus and several haemulids. At Mios, another rich otolith site located more to the north, otoliths essentially belong to typical marine near shore fishes, among which there are even some gadids, a family of more northern fishes; sciaenids are very rare there. Here also, environmental differences are apparently responsible for the differences among the associations.
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