Palaeoheterodonta is a subclass of

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

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 esti ...

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 d ...

Unionida 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 ...

(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 '' Megatrigoniidae '' is an extinct family of fossil saltwater clams, marine bivalve molluscs in the subclass Palaeoheterodonta. This family of bivalves is known in the fossil record from the Jurassic period, Tithonian age, to the Cretaceous peri ...

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 Trigonioidea is superfamily of medium-sized saltwater clams, marine bivalve molluscs. Within the fossil record the occurrence of this superfamily is widespread, ranging from the Devonian Period to Recent. The diagnostic feature for the superfam ...

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 biolog ...

, 1819 **

Trigoniidae Trigoniidae is a taxonomic family of saltwater clams, marine bivalve mollusks in the superfamily Trigonioidea. There is only one living genus, '' Neotrigonia'', but in the geological past this family was well represented, widespread and common. ...

, 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 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 ...

*Superfamily † Archanodontoidea Modell, 1957 (placement in Unionoida uncertain) **Family † Archanodontidae Modell, 1957 *Superfamily Etherioidea Deshayes, 1832 **Family

Etheriidae Etheriidae is a small family of medium-sized freshwater mussels, aquatic bivalve molluscs in the order Unionida. It contains two monotypic genera. Genera Genera within the family Etheriidae include: * '' Acostaea'' d'Orbigny, 1851 ** '' Acos ...

Deshayes, 1832 (syn: Mulleriidae, Pseudomulleriidae) **Family

Iridinidae Iridinidae is a family of medium-sized freshwater mussels, aquatic bivalve mollusks in the order Unionida Unionida is a monophyletic order of freshwater mussels, aquatic bivalve molluscs.Bieler R., Carter J.G. & Coan E.V. (2010). ''Classif ...

Swainson, 1840 (syn: Mutelidae, Pleiodontidae) **Family

Mycetopodidae The Mycetopodidae are a family of freshwater pearly mussels in the order Unionida restricted to South America. They are named for the mushroom-like shape of their foot. Like all members of the Unionida Unionida is a monophyletic order of fr ...

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 la ...

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

Rafinesque Constantine Samuel Rafinesque-Schmaltz (; October 22, 1783September 18, 1840) was a French 19th-century polymath born near Constantinople in the Ottoman Empire and self-educated in France. He traveled as a young man in the United States, ultimat ...

, 1820 **Family

Unionidae The Unionidae are a family of freshwater mussels, the largest in the order Unionida, the bivalve molluscs sometimes known as river mussels, or simply as unionids. The range of distribution for this family is world-wide. It is at its most diverse ...

, 1820 **Family Liaoningiidae Yu & Dong, 1993 (placement uncertain) **Family Margaritiferidae Henderson, 1929 (syn:Margaritaninae, Cumberlandiinae, Promargaritiferidae) **Family † Sancticarolitidae Simone & Mezzalira, 1997

References

Bivalve taxonomy Mollusc subclasses {{bivalve-stub

2010 Taxonomy of the Palaeoheterodonta

Order: Trigoniida

Order: Unionida 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 ...

References

Order:
Unionida 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 ...