Bassleroceratidae

Bassleroceratids, family Bassleroceratidae, are nautiloid cephalopods from the lower Ordovician with elongate, gradually expanded shells with a slight to moderate exogastric curvature. They are regarded as either derived ellesmerocerids that gave rise to the coiled tarphycerids as well as to the varied onchocerids or as ancestral tarphycerids.

References:

Rousseau H. Flower 1964, The Nautiloid Order Ellesmerocerida (Cephalopoda). New Mexico Bureau of Mines and Mineral Resources Memoir 12. W.M. Furnish and Brian F. Glenister 1964, Natiloidea - Ellesmerocerida. Treatise on Invertebrate Paleontology, Part K.