Palaeoheterodonta is a subclass of

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of marine and freshwater Mollusca, molluscs that have laterally compressed bodies enclosed by a shell consisting of two hing ...

mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is est ...

s. It contains the extant

orders Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of ...

Unionida (freshwater mussels) and Trigoniida. They are distinguished by having the two halves of the shell be of equal size and shape, but by having the hinge teeth be in a single row, rather than separated into two groups, as they are in the clams and cockles.

2010 Taxonomy of the Palaeoheterodonta

In 2010 a new proposed classification system for the Bivalvia was published in by Bieler, Carter & Coan revising the classification of the Bivalvia, including the subclass Paleoheterodonta.Bieler, R., Carter, J.G. & Coan, E.V. (2010) ''Classification of Bivalve families''. Pp. 113-133, in: Bouchet, P. & Rocroi, J.P. (2010), ''Nomenclator of Bivalve Families. Malacologia'' 52(2): 1-184 Superfamilies and families as listed by Bieler ''et al''. Use of † indicate families and superfamilies that are extinct. Subclass: Palaeoheterodonta

Order: Trigoniida

*† Beichuanioidea Liu & Gu, 1988 **† Beichuaniidae Liu & Gu, 1988 *† Megatrigonioidea Van Hoepen, 1929 **† Megatrigoniidae Van Hoepen, 1929 **† Iotrigoniidae Savelive, 1958 **† Rutitrigoniidae Van Hoepen, 1929 *† Myophorelloidea Kobayashi, 1954 **† Myophorellidae Kobayashi, 1954 **† Buchotrigoniidae Leanza, 1993 **† Laevitrigoniidae Savelive, 1958 **† Vaugoniidae Kobayashi, 1954 * Trigonioidea

Lamarck Jean-Baptiste Pierre Antoine de Monet, chevalier de Lamarck (1 August 1744 – 18 December 1829), often known simply as Lamarck (; ), was a French naturalist, biologist, academic, and soldier. He was an early proponent of the idea that biolo ...

, 1819 ** Trigoniidae

, 1819 **† Eoschizodidae Newell & Boyd, 1975 (syn: Curtonotidae) **† Groeberellidae Pérez, Reyes, & Danborenea 1995 **† Myophoriidae Bronn, 1849 (syn: Cytherodontidae, Costatoriidae, Gruenewaldiidae) **† Prosogyrotrigoniidae Kobayashi, 1954 **† Scaphellinidae Newell & Ciriacks, 1962 **† Schizodidae Newell & Boyd, 1975 **† Sinodoridae Pojeta & Zhang, 1984

Order: Unionida

*Superfamily † Archanodontoidea Modell, 1957 (placement in Unionoida uncertain) **Family † Archanodontidae Modell, 1957 *Superfamily Etherioidea Deshayes, 1832 **Family Etheriidae Deshayes, 1832 (syn: Mulleriidae, Pseudomulleriidae) **Family Iridinidae Swainson, 1840 (syn: Mutelidae, Pleiodontidae) **Family Mycetopodidae Gray, 1840 *Superfamily Hyrioidea Swainson, 1840 **Family

Hyriidae Hyriidae is a taxonomic family of pearly freshwater mussels, aquatic bivalve molluscs in the order Unionida. This family is native to South America, Australia, New Zealand and New Guinea. Like all members of that order, they go through a larv ...

Swainson, 1840 *Superfamily † Trigonioidoidea Cox, 1952 **Family † Trigonioididae Cox, 1952 **Family † Jilinoconchidae Ma, 1989 (placement uncertain) **Family † Nakamuranaiadidae Guo, 1981 (syn:Sinonaiinae, Nippononaiidae) **Family † Plicatounionidae Chen, 1988 **Family † Pseudohyriidae Kobayashi, 1968 **Family † Sainschandiidae Kolesnikov, 1977 *Superfamily

Unionoidea Unionida is a monophyletic order of freshwater mussels, aquatic bivalve molluscs.Bieler R., Carter J.G. & Coan E.V. (2010). ''Classification of Bivalve families''. pp. 113–133, in: Bouchet P. & Rocroi J.-P. (2010), ''Nomenclator of Bivalve Fa ...

Rafinesque, 1820 **Family Unionidae Rafinesque, 1820 **Family Liaoningiidae Yu & Dong, 1993 (placement uncertain) **Family

Margaritiferidae Margaritiferidae is a family of medium-sized freshwater mussels, aquatic bivalve molluscs in the order Unionida. Text may have been copied from this source, which is available under Attribution 4.0 International (CC BY 4.0)licence. It is the ...

Henderson, 1929 (syn:Margaritaninae, Cumberlandiinae, Promargaritiferidae) **Family † Sancticarolitidae Simone & Mezzalira, 1997

References

Bivalve taxonomy Mollusc subclasses {{bivalve-stub