Belongs within: Mytilidae. Modiolus is a genus of mussels generally regarded as dating from the Devonian to the present day, though some have suggested that the name should be restricted to Caenozoic forms (Hodges 2000). Modiolus species commonly bear a hairy external covering derived from the periostracum, the organic outer layer of the shell. Living… Continue reading Modiolus


Belongs within: Bivalvia.Contains: Praecardioida, Chaenocardiidae, Lithodomus, Aviculidae, Daonella, Halobia, Mytilidae, Condylocardiidae, Carditidae, Astartidae, Crassatellidae, Nuculanoidea, Pectinida, Pterioida, Cyrtodontidae, Limopsoidea, Arcidae. The Pteriomorphia are an ecologically diverse subdivision of bivalves including such forms as scallops, oysters and mussels. Recent molecular analysis has supported a broad definition of the clade including the clades Nuculanoidea and Carditoida as well… Continue reading Pteriomorphia


Belongs within: Pteriomorphia.Contains: Palaeoneilo, Nuculana, Yoldia. The Nuculanoidea are a group of infaunal bivalves whose earliest representatives are recorded from the Ordovician. Their shells are posteriorly elongate, though the degree of elongation varies from only slight to prominently so. Members of the family Nuculanidae possess a resilifer and have a partially internal ligament whereas the… Continue reading Nuculanoidea


Belongs within: Pteriomorphia.Contains: Glycymeris, Tucetona, Limopsis, Hochstetteria, Lissarca. The Limopsoidea are a group of bivalves that first appeared in the Lower Permian. Members of the family Glycymerididae are commonly known as ‘dog cockles’ in reference to their resemblance to the distantly related true cockles (Cardiidae). The shell is more or less equilateral in Glycymerididae but… Continue reading Limopsoidea


Belongs within: Arcidae. The Arcinae are a group of byssally-attached bivalves that are first definitely known from the Jurassic. Members of the type genus, Arca, have elongate, inaequilateral shells with a subrectangular to subtrapezoidal shape, that are commonly expanded or auriculate posteriorly. Acar has an ovoid shell with a prominent posterior umbonal carina and uniform,… Continue reading Arcinae


Belongs within: Pectinidae. Chlamys is a genus of scallops that first appeared in the Triassic. Members of the genus generally live in fissures attached to the substrate by a byssus. In members of the type subgenus, the cardinal teeth of the hinge are weak or nearly obsolete. The Late Cretaceous subgenus Lyriochlamys is characterised by… Continue reading Chlamys


Belongs within: Carditidae. Venericardia is a Cenozoic genus of cockle-like bivalves. Members have a thick, inequilateral shell with numerous radial ribs that are evenly elevated when young but become flattened and enlarged with age. The shell is subquadrangular in shape in the type subgenus but more transversely elliptical in Megacardita. Venericardia Lamarck 1801DK10 |–*V. imbricataDK10… Continue reading Venericardia