No more Basslerocerida

The late Rousseau Flower in Flower and Kummel, 1950, in the Journal of Paleontology, Sept 1950 set up the Bassleroceratida as an order of nautiloid cephalopods intermediary between the more primitive, generally straight shelled Ellesmerocerida and the more evolved, coiled Tarphycerida and later Barrandeocerida. Basslerocerids are exemplified by the upwardly curved genus Bassleroceras in which the lower or ventral side is longitudinally convex and the upper or dosal side is curved in the opposite sense. The order at that time included two families, the Bassleroceratidae and Graciloceratidae.

Seven years later, Flower 1957 in Flower and Teichert, in a University of Kansas publication on the Discosorida, abandoned the Bassleroceratida and instead included the Bassleroceratidae, with thick connecting rings in the Tarphycerida and the Graciloceratidae with thin connecting rings in the Oncocerida.

Taking a somewhat difference approach, W.M, Furnish and Brian Glenister in the original, 1964 edition of Part K of the Treatise on Invertebrate Paleontology, included the Bassleroceratidae in the ancestral Ellesmerocerida . Walter Sweet on the otherhand followed Flower's perspective and retained the Graciloceratidae in the Oncocerida. Later, Flower, 1976, in a publication of the Palaeontological Society ( Gr Br) on Ordovician Cephalopod Faunas, shows the Bassleroceratidae in the Tarphyceratida (same as Tarphycerida), with the earlier more primitive forms giving rise to the Tarphyceratidae and the more derived forms later giving rise to the Oncocerida following his original (1957) idea.

So, to conclude, no more Basslerocerida. The order should be regarded as unnecessary, more so than "invalid". Never-the-less Shevyrev, 2006, according to the Paleobiology Database website, retained the Basslerocerida as a distinct nautiloid order, with the Barrandeocerina its sole suborder. This follows neither the sense of Flower (1950, 1957, and 1976), of the Treatise Part K, 1964, Teichert et al, or of Teichert 1988. For one thing the Barrandeocerina ( ex Barrandeocerida) are clearly derived from the Tarphyceratidae and therefore cannot be part of the Basslerocerida, regardless. Since what is presented on line is not necessarily what is in the original, perhaps Basslerocerida should really be Barandeoceida, which makes more sense.