Category: Helcionellida

Belongs within: Helcionellida. The Scenellidae are a group of univalved molluscs known from the Early Cambrian, with a simple cap-shaped shell without a peripheral buttress (Parkhaev 2002, as Helcionellidae). The shell is lower in the Scenellinae than in Yangtzeconinae with the aperture length exceeding shell height. <==Scenellidae [Helcionellidae] |–Yangtzeconinae [Yangtzeconiacea, Yangtzeconidae]BR17 | |–Yangtzeconus Yu 1979BR17… Continue reading Scenellidae

Belongs within: Mollusca.Contains: Securiconidae, Stenothecidae, Yochelcionellidae, Scenellidae, Coreospiridae. The Helcionellida are an Early Cambrian assemblage of cap-shaped to planispiral shells of contested affinities. Characters (Parkhaev 2002, as Helcionelliformes): Shell symmetrical, cap-shaped, planispiral or close to planispiral with few coils. Forms with planispiral shell have elongated aperture, with length larger, equal or slightly smaller than shell diameter. <==Helcionellida [Helcionelliformes,… Continue reading Helcionellida

Belongs within: Helcionellida. The Coreospiridae are a group of univalved molluscs from the Early to Middle Cambrian with a planispiral or near-planispiral shell of few coils (Parkhaev 2002). The last whorl is compressed with an elongate aperture (Parkhaev 2008). <==Coreospiridae [Coreospiroidei] |–Cambrospira Yu 1979P02 |–Hugiagouella Chen & Zhang 1980P02 |–Cambroconus Yu 1981P02 |–Hubeispira Yu 1981P02… Continue reading Coreospiridae