Margaritiferidae is a

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

of medium-sized freshwater mussels, aquatic

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 in the order Unionida. CC-BY icon

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licence. It is the most threatened of all unionid families. The family is sometimes referred to as the freshwater pearl mussel family, but " freshwater pearl mussel" more often applies to the species ''Margaritifera margaritifera''. The name refers to the thick layer of nacre (mother of pearl) lining the interior of the shell of the species, which enables them to produce

pearl A pearl is a hard, glistening object produced within the soft tissue (specifically the mantle) of a living shelled mollusk or another animal, such as fossil conulariids. Just like the shell of a mollusk, a pearl is composed of calcium carb ...

Taxonomy

A 2018 study suggested a new

phylogeny A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological s ...

and

systematics Biological systematics is the study of the diversification of living forms, both past and present, and the relationships among living things through time. Relationships are visualized as evolutionary trees (synonyms: cladograms, phylogenetic t ...

of the Margaritiferidae, comprising two subfamilies, Gibbosulinae and Margaritiferinae, and four genera, ''Gibbosula'', ''Cumberlandia'', ''Margaritifera'', and ''Pseudunio''. This family has ancient origins, having diverged from the ancestors of the Unionidae during the

Late Triassic The Late Triassic is the third and final epoch of the Triassic Period in the geologic time scale, spanning the time between Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch and followed by the Early Jurassic Epoch ...

with the crown group of the Margaritiferidae arising by the Middle Jurassic, and both extant subfamilies diverging by the Late Jurassic. All extant genera diverged from one another by the Late Jurassic or

Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145& ...

Genera

Genera within the family Margaritiferidae include:

Subfamily Margaritiferinae

* '' Cumberlandia'' Ortmann, 1912 * '' Margaritifera'' Schumacher, 1815 * '' Pseudunio'' Haas, 1910

Subfamily Gibbosulinae

* '' Gibbosula'' Simpson, 1900

Fossil genera

Several fossil genera are known, dating back to the Middle Jurassic: * †'' Palaeomargaritifera'' Ma, 1984 (Middle Jurassic of

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) * Subfamily Margaretiferinae ** †'' Asturianaia'' Van Damme & Bogan, 2015 (Middle to Late Jurassic of

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) ** † “''Margaritifera''” ''crosthwaitei'' (Newton, 1909) (Late Jurassic of

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) ** †'' Paraheudeana'' (

of Spain)

References

{{Taxonbar, from=Q3018668 Bivalve families Extant Middle Jurassic first appearances