Abstract The geographical distribution of rostroconch taxa of the orders Ribeirioida and Conocardiida, mostly across the equatorial continents and oceans, is compiled for six presumed diversity acmes in the early Early Ordovician ( c. 485 Ma), the late Early–early Middle Ordovician ( c. 475 Ma), the Late Ordovician ( c. 455 Ma), the Early Silurian ( c. 435 Ma), the late Early–early Late Silurian ( c. 425 Ma) and the early Early Devonian ( c. 415 Ma), based on our present, uneven knowledge. Rostroconchs show distribution patterns which enable a provisional separation of biogeographical provinces at least from the Silurian onward, comparable with Late Palaeozoic rostroconch distributional patterns. The distributions of tabulate corals, trilobites and bivalves appear roughly comparable, but not the nektic and planktic groups. A restriction to low latitudes (‘tropical’ realms) is clear for members of Ribeiria and Eopteria in the Early Ordovician, similar to proven patterns for hippocardiid rostroconchs from the Late Silurian onward until the Middle Permian. Preliminary rostroconch provinces or subprovinces, respectively, are currently discernable in the Silurian and Devonian for northwestern Laurentia, south-central Laurentia/Baltica and the north-central margin of Gondwana (i.e. Perunica, Bohemia). Rostroconch distributional data for SE Asia, China, Kazakhstan, Siberia and Australia are sparse and require further studies.

Abstract 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.