Barrandeocerida

Barrandeocerids are mostly coiled nautiloid cephalopods comprising some six families, that lived from the Middle Ordovician to the Middle Devonian, a span of around 100 million years. Derivation is from within the Tarphyceratidae.

Shells are variably coiled, some planar, others trochoidal. Siphuncles have thin-walled connecting rings, which distinguishes them from the tarphycerids in which connecting rings are thick-walled and layered.

The following six families, starting with the oldest, have been described. Barrandeoceratidae M Ord - M Dev Plectoceratidae: M -U Ord Aspidoceratidae: M-U Ord Uranoceratidae:  U Ord - M Sil. Lechritrochoceratidae: M -U  Sil Nephiticeratidae: L -M Dev

The last of the barrandeocerids became extinct near the end of the Middle Devonian, apparently without giving rise to any progeny.

References Walter C. Sweet, 1964. Nautilodea - Barrandeocerida. Treatise on Invertebrate Paleontology. Part K   (K368 -K382) Mary Wade, 1988. Nautiloids and their descendants: cephalopod classification in 1986. New Mexico Bureau of Mines & Mineral Resources Memoir 44