Heteroconchia

These bivalves are distinguished by having the two halves of the shell equally sized (i.e., they are equivalved) and having a few cardinal teeth separated from a number of long lateral teeth. Their shells lack a nacreous layer, and the gills are lamellibranch in form. Most species have a siphon. == Orders and families ==

The following tree is their info which has been updated with the latest information from the World Register of Marine Species: • Order: †Actinodontida • Superfamily: †Amnigenioidea • Family: †Amnigeniidae • Family: †Montanariidae • Family: †Zadimerodiidae • Superfamily: †Anodontopsoidea • Family: †Actinodontidae • Family: †Anodontopsidae • Family: †Baidiostracidae • Family: †Cycloconchidae • Family: †Intihuarellidae • Family: †Redoniidae • Superfamily: †Nyassoidea • Family: †Nyassidae • Superfamily: †Oriocrassatelloidea • Family: †Crassatellopsidae • Family: †Oriocrassatellidae • Superfamily: †Palaeomuteloidea • Family: †Palaeomutelidae • Order: Carditida • Unclassified family: †Archaeocardiidae • Unclassified family: †Eodonidae • Superfamily: Carditoidea • Family: †Cardiniidae • Family: Carditidae • Family: Condylocardiidae • Superfamily: Crassatelloidea • Family: †Aenigmoconchidae • Family: Astartidae • Family: Crassatellidae • Family: †Myophoricardiidae • Subterclass: Euheterodonta • Unassigned Euheterodonta • Superfamily: †Babinkoidea • Superfamily: †Orthonotoidea • Superorder: Anomalodesmata • Superfamily: Clavagelloidea • Family: Clavagellidae • Family: Penicillidae • Superfamily: Cuspidarioidea • Family: Cuspidariidae • Family: Halonymphidae • Family: Protocuspidariidae • Family: Spheniopsidae • Superfamily: Myochamoidea • Family: Cleidothaeridae • Family: Myochamidae • Superfamily: Pandoroidea • Family: Lyonsiidae • Family: Pandoridae • Superfamily: Pholadomyoidea • Family: †Arenigomyidae • Family: †Margaritariidae • Family: Parilimyidae • Family: Pholadomyidae • Family: †Ucumariidae • Superfamily: Poromyoidea • Family: Cetoconchidae • Family: Poromyidae • Superfamily: Thracioidea • Family: †Burmesiidae • Family: Clistoconchidae • Family: Laternulidae • Family: Periplomatidae • Family: Thraciidae • Superfamily: Verticordioidea • Family: Euciroidae • Family: Lyonsiellidae • Family: Verticordiidae • Superorder: Imparidentia • Unassigned Imparidentia • Unassigned Family: †Palaeocarditidae • Superfamily: Cyamioidea • Family: Cyamiidae • Family: Galatheavalvidae • Family: Sportellidae • Superfamily: Gaimardioidea • Family: Gaimardiidae • Superfamily: †Grammysioidea • Family: †Grammysiidae • Family: †Sanguinolitidae • Superfamily: †Kalenteroidea • Family: †Kalenteridae • Order: Adapedonta • Superfamily: †Edmondioidea • Family: †Edmondiidae • Family: †Pachydomidae • Superfamily: Hiatelloidea • Family: Hiatellidae • Superfamily: Solenoidea • Family: Pharidae • Family: Solenidae • Order: Cardiida • Superfamily: Cardioidea • Family: Cardiidae • Family: †Pterocardiidae • Superfamily: Tellinoidea • Family: Donacidae • Family: †Icanotiidae • Family: Psammobiidae • Family: †Quenstedtiidae • Family: Semelidae • Family: Solecurtidae • Family: †Sowerbyidae • Family: †Tancrediidae • Family: Tellinidae • Family: †Unicardiopsidae • Order: Galeommatida • Superfamily: Galeommatoidea • Family: Basterotiidae • Family: Galeommatidae • Family: Lasaeidae • Order: Gastrochaenida • Superfamily: Gastrochaenoidea • Family: Gastrochaenidae • Order: †Hippuritida (rudists) • Suborder: †Hippuritidina • Superfamily: †Caprinoidea • Family: †Antillocaprinidae • Family: †Caprinidae • Family: †Caprinuloideidae • Family: †Ichthyosarcolitidae • Superfamily: †Radiolitoidea • Family: †Caprinulidae • Family: †Caprotinidae • Family: †Diceratidae • Family: †Hippuritidae • Family: †Monopleuridae • Family: †Plagioptychidae • Family: †Polyconitidae • Family: †Radiolitidae • Family: †Trechmannellidae • Suborder: †Requieniidina • Superfamily: †Requienioidea • Family: †Epidiceratidae • Family: †Requieniidae • Order: Lucinida • Superfamily: Lucinoidea • Family: Lucinidae • Family: †Mactromyidae • Family: †Paracyclidae • Superfamily: Thyasiroidea • Family: Thyasiridae • Order: †Megalodontida • Superfamily: †Mecynodontoidea • Family: †Beichuaniidae • Family: †Congeriomorphidae • Family: †Mecynodontidae • Family: †Plethocardiidae • Family: †Prosocoelidae • Superfamily: †Megalodontoidea • Family: †Ceratomyopsidae • Family: †Dicerocardiidae • Family: †Megalodontidae • Family: †Pachyrismatidae • Family: †Wallowaconchidae • Order: †Modiomorphida • Superfamily: †Modiomorphoidea • Family: †Cypricardiniidae • Family: †Hippopodiumidae • Family: †Modiomorphidae • Family: †Palaeopharidae • Family: †Tusayanidae • Order: Myida • Superfamily: Dreissenoidea • Family: Dreissenidae • Superfamily: Myoidea • Family: Corbulidae • Family: Myidae • Family: †Pleurodesmatidae • Family: †Raetomyidae • Superfamily: Pholadoidea • Family: Pholadidae • Family: Teredinidae (shipworms) • Family: Xylophagaidae • Superfamily: †Pleuromyoidea • Family: †Ceratomyidae • Family: †Pleuromyidae • Family: †Vacunellidae • Order: Sphaeriida • Superfamily: Sphaerioidea • Family: †Neomiodontidae • Family: Sphaeriidae • Order: Venerida • Superfamily: †Anthracosioidea • Family: †Anthracosiidae • Family: †Ferganoconchida • Family: †Shaanxiconchidae • Superfamily: Arcticoidea • Family: Arcticidae • Family: †Pollicidae • Family: Trapezidae • Family: †Veniellidae • Superfamily: Chamoidea • Family: Chamidae • Superfamily: Cyrenoidea • Family: Cyrenidae • Family: Cyrenoididae • Family: Glauconomidae • Superfamily: Glossoidea • Family: Glossidae • Family: Kelliellidae • Family: †Lutetiidae • Family: Vesicomyidae • Superfamily: Hemidonacoidea • Family: Hemidonacidae • Superfamily: Mactroidea • Family: Anatinellidae • Family: Cardiliidae • Family: Mactridae • Family: Mesodesmatidae • Superfamily: †Palaeanodontoidea • Family: †Palaeanodontidae • Superfamily: †Prilukielloidea • Family: †Prilukiellidae • Family: †Senderzoniellidae • Superfamily: Ungulinoidea • Family: Ungulinidae • Superfamily: Veneroidea • Family: †Isocyprinidae • Family: Neoleptonidae • Family: Veneridae • Subterclass: Paleoheterodonta • Unassigned Family: Lyrodesmatidae • Unassigned Family: Pseudarcidae • Unassigned Family: Thoraliidae • Order: Unionida • Unassigned Genus †Araripenaia • Unassigned Family †Pachycardiidae • Superfamily Etherioidea • Superfamily †Silesunionoidea • Superfamily †Tamesnelloidea • Superfamily Unionoidea • Order: Trigoniida • Superfamily †Megatrigonioidea • Superfamily Myophorelloidea • Superfamily Pseudocardinioidea • Superfamily Trigonioidea • Superfamily Trigonioidoidea • Superfamily Trigonodoidea • Subterclass: Heterodonta ==References==