Bivalvia - Ostreida - Malleidae
Parent taxon: Isognomon according to E. J. Moore 1983
See also Matsubara 2002
Sister taxa: Isognomon (Hippochaeta), Isognomon (Iranognomon), Isognomon (Melina), Isognomon (Mulletia), Isognomon (Parviperna), Isognomon (Semignomon), Isognomon alatus, Isognomon bicolor, Isognomon gariesensis, Isognomon gaudichaudi, Isognomon isognomoides, Isognomon isognomon, Isognomon isognomonoides, Isognomon legumen, Isognomon maxillata, Isognomon nucleus, Isognomon orientalis, Isognomon perna, Isognomon quadrisulcata, Isognomon radiatus, Isognomon repini, Isognomon valvanoi
Subtaxa: Isognomon (Isognomon) clarki Isognomon (Isognomon) exilis Isognomon (Isognomon) janus Isognomon (Isognomon) panzana Isognomon (Isognomon) rekohuensis
Ecology: stationary epifaunal suspension feeder
Distribution:
• Miocene of United States (6: California collections)
• Eocene of United States (8: California, Oregon, Washington)
• Cretaceous of Japan (3), New Zealand (4)
• Jurassic of Argentina (2), Canada (1: British Columbia), Chile (1), China (1), France (2), Germany (4), Japan (2), Portugal (1), the United Kingdom (1)
• Triassic of Austria (5), Hungary (3), Italy (2), Spain (1)
Total: 47 collections including 49 occurrences