Order Barrandeocerida Flower in Flower & Kummel, 1950

Remarks

The order Barrandeocerida was not accepted by Dzik (1984: 46), who placed the genus Barrandeoceras Hyatt, 1884 within the Tarphyceratidae, or by Flower (1984: 1377), who placed the family Barrandeoceratidae within the Tarphycerida . However, Barrandeoceras and similar forms, which were assigned to the Barrandeocerida by Flower & Kummel (1950) and Sweet (1964a) are clearly distinguished from Tarphycerida in having a thin-walled orthocerid-like siphuncle with achoanitic to cyrtochoanitic septal necks. The differences between the connecting ring structure and morphology in tarphycerids and barrandeocerids were examined and discussed by Mutvei & Dunca (2011), renewing earlier hypotheses (see Flower 1984) of an orthocerid ancestry for the Barrandeocerida (see discussion below).