Systematic Paleontology
Class Cephalopoda
Subclass Bactritoidea
Order Bactritida
Family Bactritidae
Genus Bactrites
Bactrites is a small orthoconic cephalopod with a range extending from the Silurian to the Permian that ultimately gave rise to both the ammonites and belemnites.
Shells of Bactrites are straight and fairly narrow, nearly circular to broadly oval in cross section. Siphuncles are ventro-marginal and retrochoanitic, as indicated by the septal necks directed backwards toward the apex of the shell. Sutures have a small ventral lobe, otherwise are simple, transverse and nearly straight. Septa tend to be close spaced resulting in short chambers, or camerae.
Bactrites belongs to the Bactritidae as the type genus, and to the Bactritoidea which also includes the Parabactritidae; and gave rise to the Ammonoidea in the Early Devonian through Lobobactrites followed by Cyrtobactrites. Derivation is most likely from the Ordovician Eobactrities, or some related genus, which has its origin in the nautiloid Orthocerida.
References
- Erben, H.K. 1964. Bactritoidea. Treatise on Invertebrate Paleontology, Part K (K501). Geological Society of America and University of Kansas Press.
- Bactrites in Fossilworks Gateway.