Belongs within: Macluritida. On Platyschismatinae Published 26 September 2017 In an earlier post on this site, I commented on some of the various ways that gastropods deal with the fact that their development tends to put their anus uncomfortably close to their mouth. A common solution is the development of a sinus or slit in… Continue reading Platyschismatinae


Belongs within: Macluritida.Contains: Euomphalus, Straparollus. The Euomphalidae are a group of often discoidal gastropods known from the Ordovician to the Triassic, generally with a sharp dorsal ridge marking the position of the exhalant channel. Characters (from Knight et al. 1960): Shell mostly discoidal with wide umbilicus, but varying widely in form; abandoned early part of… Continue reading Euomphalidae


Belongs within: Gastropoda.Contains: Trochonematidae, Lophospiridae, Euomphalidae, Raphistomatidae, Helicotomidae, Omphalotrochidae, Platyschismatinae, Turbonellininae. The Ordovician to Middle Triassic Trochonematoidea included the gastropod families Trochonematidae and Lophospiridae. The two families shared a characteristic shell morphology: a median angulation running along or above the midline of each spire (replaced by a shallow sinus in some Trochonematidae), with further angulations… Continue reading Macluritida