Basslerocerida is an order of nautiloid cephalopods from the Ordovician comprising exogastric longiconic cyrtocones,[1] that is no longer in common use.
The Order Basslerocerida was established by Flower and Kummel (1950) for forms intermediary between the ancestral Ellesmerocerida and the more advanced Tarphycerida and Oncocerida.
Basslerocerida has fallen into general disuse, the taxa now being included in either the Ellesmerocerida or in the derived Tarphycerida and Oncocerida, although Sheverev (2006)[2] continued to recognize the order.
Shells are rather small, reaching lengths of about 12 –15 cm (5 –6 in); elongate with an upward, exogastric, curvature -like a rocker -and subcircular to laterally compressed cross-section.
[3][4] The siphuncle in the Bassleroceratidae is composed of thick connecting rings, as found in the ancestral Ellesmerocerida and in primitive Tarphycerida.