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Institut für Geologie und Paläontologie der Philipps-Universität Marburg, Abteilung Invertebraten-Paläontologie, Hans-Meerwein-Strasse, 35032 Marburg, Germany
(e-mail: rogalla{at}mailer.uni-marburg.de)
(e-mail: amler{at}mailer.uni-marburg.de)
Bedded carbonaceous siltstones from the Buechel Subformation of the Bergisch-Gladbach-Paffrath Syncline, Germany, of Middle Devonian (Middle Givetian) age have yielded a remarkable sample of extremely elongated, articulated bivalves preserved in life orientation. The specimens are associated with a single left valve embedded horizontally in the bedding plane and further isolated but articulated shells. Combining the information given by the specimens and the palaeobiological interpretations allows the reconstruction of the complete morphology and probable life habits. The very distinct morphological features led to the erection of a new taxon, Teranota ebbighauseni Rogalla & Amler, 2000, provoking discussion on habitats, life habits and evolutionary trends in anomalodesmatan bivalves. A combination of characters typical of the orthonotids and the modiomorphids, as well as the preserved life position at an angle of some 60–70° relative to the bedding plane, suggests that these specimens were part of a minor branch off the main evolutionary lineages within the Anomalodesmata. It is proposed that these animals represent a convergent line of endobenthic bivalves distantly related to true siphonate forms.
