Ordovician – Devonian
Praenuculidae is an extinct family of facultatively mobile shallow infaunal deposit feeders
Description of the Family
- Hinge contains chevron teeth
- Convexodont and concavadont dentition
- Resilifer absent
- The typical dental pattern of the Praenuculidae consists of the chevroned teeth with the chevron angles open toward the distal borders of the hinge. As Babin and Melou (1972) noted, this pattern is an important diagnostic feature, and an inverse disposition, in which the chevron angles are oriented in the opposite direction led them to erect the genus Concavodonta Babin and Melou. In view of these features, two types of definition can be recognized: convexodont, as in the type genus of the family, Praenucula, and concavadont, as in Concavadonta. This clear difference forms the basis for erecting two new subfamiles among the Praenuculidae, the subfamily Praenuculinae, for praenuculids Concavoleda, in which diagnostic characters of the family are associated to a concavodontid condition.
- Studied specimens show the typical features of the Family Praenuculidae such as dentition continuous below the umbo, and truncate posterior extremity (McAlester, 1969a, p. 229).
Morris & Fortey (1976):
- Tironucula and other Praenuculidae are shown to be infaunal deposit feeders with a mantle cavity of similar form to the living Nuculidae rather than the protobranch filter feeders Nucinella and Solemya. It is suggested that this arrangement is primitive for the Bivalvia.
Treatise on Invertebrate Paleontology, Part N, Mollusca 6(1 of 3) (1969):
- Resilifer absent, ligament external.