Bivalvia - Cardiida - Cardiidae
Alternative spelling: Keenaea
Parent taxon: Nemocardium according to E. J. Moore 2003
See also Coan et al. 2000, Moore 1976, Schneider 1995, Sepkoski 2002 and Vokes 1980
Sister taxa: Cardium (Nemocardium) bhagothorense, Cardium (Nemocardium) brasiliense, Nemocardium (Arctopratulum), Nemocardium (Brevicardium), Nemocardium (Divaricardium), Nemocardium (Lophocardium), Nemocardium (Lyrocardium), Nemocardium (Nemocardium), Nemocardium (Pratulum), Nemocardium (Trifaricardium), Nemocardium (Varicardium), Nemocardium bechei, Nemocardium cooperii, Nemocardium eugenense, Nemocardium ezoense, Nemocardium granosulcatum, Nemocardium hadraterum, Nemocardium lene, Nemocardium lincolnensis, Nemocardium nicoletti, Nemocardium nicolletti, Nemocardium nitens, Nemocardium parile, Nemocardium patulum, Nemocardium plumsteadianum, Nemocardium salrivale, Nemocardium semiasperum, Nemocardium semitectum, Nemocardium turgidum
Subtaxa: Nemocardium (Keenaea) centifilosum
Ecology: facultatively mobile infaunal suspension feeder
Distribution:
• Quaternary of United States (24: California collections)
• Pliocene to Pleistocene of United States (4: California)
• Pliocene of United States (4: California)
• Miocene of Japan (1), the Russian Federation (3)
Total: 36 collections each including a single occurrence