Gastropoda - Opisthobranchia - Retusidae
Alternative spelling: Cylichnina
Parent taxon: Retusa according to O. Mandic and F. F. Steininger 2003
See also Durham 1944, Harris and Palmer 1947, Harzhauser and Kowalke 2002, Martin 1904, Palmer and Brann 1966, Sepkoski 2002, Squires 1984, Squires 1987, Squires 1988, Squires 1999, Squires and Demetrion 1992, Todd 2001 and Turner 1938
Sister taxa: Retusa (Coleophysis), Retusa bizona, Retusa claibornensis, Retusa galba, Retusa jacksonensis, Retusa jacksonesis, Retusa obtusa, Retusa recta, Retusa truncatula, Retusa yaquensis
Subtaxa: Cylichnina coelata Cylichnina petrosa Cylichnina tantilla Cylichnina turneri Retusa (Cylichnina) aequiattenuata Retusa (Cylichnina) conutus Retusa (Cylichnina) galba Retusa (Cylichnina) marylandica Retusa (Cylichnina) subspissa
Ecology: epifaunal carnivore
Distribution:
• Quaternary of Portugal (1 collection)
• Pliocene of Belgium (2), Venezuela (2)
• Miocene of Algeria (1), Austria (2), Brazil (2), Denmark (1), Germany (34), Iran (3), Kazakhstan (1), the Netherlands (2), Panama (8), United States (12: California, Maryland, Oregon)
• Oligocene of Belgium (3), France (9)
• Eocene of Jamaica (1), Mexico (2), Pakistan (1), Panama (1), the United Kingdom (3), United States (140: Alabama, California, Louisiana, Mississippi, Oregon, Texas, Washington)
• Paleocene of United States (9: Alabama, California, Louisiana, Texas)
• Cretaceous of United States (4: California)
Total: 244 collections including 268 occurrences