Plicatostylidae is a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

of extinct large-sized epifaunal marine to brackish

bivalves Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed by a calcified exoskeleton consis ...

that inhabited

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

and

America The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

during the

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

, though they survived until the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

. These groups are informally known as "Lithiotids" or "Lithiotid Bivalves". They represent large reef builders, analogues to the younger

Rudists Rudists are a group of extinct box-, tube- or ring-shaped Marine (ocean), marine Heterodonta, heterodont bivalves belonging to the order Hippuritida that arose during the Late Jurassic and became so diverse during the Cretaceous that they were m ...

and modern '' Crassostrea'', ''

Magallana ''Magallana'' is a genus of true oysters (family Ostreidae) containing some of the most important oysters used for food. Species in this genus have been moved from ''Crassostrea'' after it was found to be paraphyletic. Species Extant species a ...

'' and less extent to ''

Tridacna ''Tridacna'' is a genus of large saltwater clams, Marine (ocean), marine bivalve molluscs in the subfamily Tridacninae, the giant clams. Many Tridacna species are threatened. They have heavy shells, fluted with 4 to 6 folds. The Mantle (mollus ...

''.

Ecology

Plicatostylid bivalves were large sized, with the

spoon A spoon (, ) is a utensil consisting of a shallow bowl (also known as a head), oval or round, at the end of a handle. A type of cutlery (sometimes called flatware in the United States), especially as part of a table setting, place setting, it ...

-shaped '' Lithiotis'' reaching heights of 25-30 cm and a thickness of up to 1.5-3 cm, with the largest as high as 50 cm and some specimens of '' Lithioperna'' reaching 70 cm and 4 cm thick. They developed in large

reef A reef is a ridge or shoal of rock, coral, or similar relatively stable material lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic component, abiotic (non-living) processes such as deposition (geol ...

systems like modern '' Crassostrea'', but in warm, shallow seas, with some bioherms attaining lengths over 60 m and thicknesses of 3-5 m. They were rapid growers, with their shells often made of

aragonite Aragonite is a carbonate mineral and one of the three most common naturally occurring crystal forms of calcium carbonate (), the others being calcite and vaterite. It is formed by biological and physical processes, including precipitation fr ...

, leading to massive shell accumulations that shaped the sea floor, known as the "Lithiotis Facies". These bivalves were major players in their marine ecosystems, contributing to the geological structure of carbonate platforms. Plicatosylids were notably widespread in the

Lower Jurassic The Early Jurassic Epoch (in chronostratigraphy corresponding to the Lower Jurassic Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic–Jurassic extinction event, 201.3 Ma&nb ...

, specially within the

Sinemurian In the geologic timescale, the Sinemurian is an age (geology), age and stage (stratigraphy), stage in the Early Jurassic, Early or Lower Jurassic epoch (geology), Epoch or series (stratigraphy), Series. It spans the time between 199.5 ±0.3 annu ...

Pliensbachian The Pliensbachian is an age of the geologic timescale and stage in the stratigraphic column. It is part of the Early or Lower Jurassic Epoch or Series and spans the time between 192.9 ±0.3 Ma and 184.2 ±0.3 Ma (million years ago). The Plie ...

, with significant occurrences in Tethyan and Panthalassan margins, from areas in Italy ( Rotzo Formation of the Trento Platform, Apennine Carbonate Platform), Slovenia (

Podpeč Limestone Podpeč may refer to several places in Slovenia: *Podpeč, Brezovica, a settlement in the Municipality of Brezovica *Podpeč, Dobrepolje, a settlement in the Municipality of Dobrepolje *Podpeč, Koper, a settlement in the Municipality of Koper *Po ...

Montenegro , image_flag = Flag of Montenegro.svg , image_coat = Coat of arms of Montenegro.svg , coa_size = 80 , national_motto = , national_anthem = () , image_map = Europe-Mont ...

( Budoš Limestone),

Spain Spain, or the Kingdom of Spain, is a country in Southern Europe, Southern and Western Europe with territories in North Africa. Featuring the Punta de Tarifa, southernmost point of continental Europe, it is the largest country in Southern Eur ...

Switzerland Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland ...

and parts of North America (e.g.

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

Nevada Nevada ( ; ) is a landlocked state in the Western United States. It borders Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the seventh-most extensive, th ...

Oregon Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...

). In

High Atlas The High Atlas, also called the Grand Atlas, is a mountain range in central Morocco, North Africa, the highest part of the Atlas Mountains. The High Atlas rises in the west at the Atlantic Ocean and stretches in an eastern direction to the Moro ...

of Morocco (ex. Aganane Formation & Tafraout Group) they are found in association with

Corals Corals are colonial marine invertebrates within the subphylum Anthozoa of the phylum Cnidaria. They typically form compact Colony (biology), colonies of many identical individual polyp (zoology), polyps. Coral species include the important Coral ...

, suggesting a different ecological context during their later survival. Some endemic species (ex. ''Lithiotis timorensis'') were described from

Timor Timor (, , ) is an island at the southern end of Maritime Southeast Asia, in the north of the Timor Sea. The island is Indonesia–Timor-Leste border, divided between the sovereign states of Timor-Leste in the eastern part and Indonesia in the ...

. Most of these bivalves met their end during a significant environmental upheaval known as the

Toarcian Oceanic Anoxic Event The Toarcian extinction event, also called the Pliensbachian-Toarcian extinction event, the Early Toarcian mass extinction, the Early Toarcian palaeoenvironmental crisis, or the Jenkyns Event, was an extinction event that occurred during the early ...

, which altered ocean chemistry and made survival challenging. Yet, in some areas like

Morocco Morocco, officially the Kingdom of Morocco, is a country in the Maghreb region of North Africa. It has coastlines on the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to Algeria–Morocc ...

or the

Apennine Mountains The Apennines or Apennine Mountains ( ; or Ἀπέννινον ὄρος; or – a singular with plural meaning; )Latin ''Apenninus'' (Greek or ) has the form of an adjective, which would be segmented ''Apenn-inus'', often used with nouns s ...

, they persisted, showing some adaptability. '' Gervilleioperna'' survived until at least the

Aalenian The Aalenian () is a subdivision of the Middle Jurassic Epoch/Series of the geologic timescale that extends from about 174.7 ±0.8 Ma to about 170.9 ±0.8 Ma (million years ago). It was preceded by the Toarcian and succeeded by the Bajocian. St ...

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

, likely due to having a small shell. The genus '' Pachyperna'' is known from the Eocene (

Bartonian The Bartonian is, in the International Commission on Stratigraphy's (ICS) geologic time scale, a stage or age in the middle of the Eocene Epoch or Series. The Bartonian Age spans the time between . It is preceded by the Lutetian and is follow ...

Priabonian The Priabonian is, in the ICS's geologic timescale, the latest age or the upper stage of the Eocene Epoch or Series. It spans the time between . The Priabonian is preceded by the Bartonian and is followed by the Rupelian, the lowest stage ...

?), revelating the group also survived the

Cretaceous–Paleogene extinction event The Cretaceous–Paleogene (K–Pg) extinction event, also known as the K–T extinction, was the extinction event, mass extinction of three-quarters of the plant and animal species on Earth approximately 66 million years ago. The event cau ...

Genera

Subfamily Pachygervilliinae: * †'' Gervilleioperna'' * †'' Lithioperna'' * †'' Pachygervillia'' * †'' Pachyperna'' Subfamily Plicatostylinae: * †'' Cochlearites'' * †'' Lithiotis'' * †'' Plicatostylus'' (type)

References

Pteriida Prehistoric bivalve families Sinemurian first appearances Sinemurian life Pliensbachian life Eocene extinctions {{Paleo-bivalve-stub