''Trigonia'' is an extinct

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

saltwater Saline water (more commonly known as salt water) is water that contains a high concentration of dissolved salts (mainly sodium chloride). On the United States Geological Survey (USGS) salinity scale, saline water is saltier than brackish wat ...

clams Clam is a common name for several kinds of bivalve mollusc. The word is often applied only to those that are deemed edible and live as infauna, spending most of their lives halfway buried in the sand of the sea floor or riverbeds. Clams h ...

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

marine

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

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

in the family

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. ...

. The fossil range of the genus spans the

Paleozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma a ...

Mesozoic The Mesozoic Era is the Era (geology), era of Earth's Geologic time scale, geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Period (geology), Periods. It is characterized by the dominance of archosaurian r ...

and

Paleocene The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), ...

of the

Cenozoic The Cenozoic Era ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterized by the dominance of mammals, insects, birds and angiosperms (flowering plants). It is the latest of three g ...

, from 298 to 56 Ma.

Description

The genus ''Trigonia'' is the most readily identifiable member of the family

, having a series of strong ribs or costae along the

anterior Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

part of the

shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses Science Biology * Seashell, a hard outer layer of a marine ani ...

exterior. They are the first representatives of the family to appear in the

Middle Triassic In the geologic timescale, the Middle Triassic is the second of three epoch (geology), epochs of the Triassic period (geology), period or the middle of three series (stratigraphy), series in which the Triassic system (stratigraphy), system is di ...

(

Anisian In the geologic timescale, the Anisian is the lower stage (stratigraphy), stage or earliest geologic age, age of the Middle Triassic series (stratigraphy), series or geologic epoch, epoch and lasted from million years ago until million years ag ...

) of Chile and New Zealand. The first European examples (''Trigonia costata'' Parkinson) appear in the Lower Jurassic (

Toarcian The Toarcian is, in the International Commission on Stratigraphy, ICS' geologic timescale, an age (geology), age and stage (stratigraphy), stage in the Early Jurassic, Early or Lower Jurassic. It spans the time between 184.2 Megaannum, Ma (million ...

) of

Sherborne Sherborne is a market town and civil parishes in England, civil parish in north west Dorset, in South West England. It is sited on the River Yeo (South Somerset), River Yeo, on the edge of the Blackmore Vale, east of Yeovil. The parish include ...

, Dorset and Gundershofen, Switzerland.

Species

The following ''Trigonia'' species have been described:''Trigonia''
at

Fossilworks Fossilworks was a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world. History Fossilworks was cr ...

.org * ''T. analoga'' * ''T. antiqua'' * ''T. castani'' * ''T. castrovillensis'' * ''T. coqueiroensis'' * ''T. costata'' * ''T. cragini'' * ''T. depauperata'' * ''T. eufaulensis gabbi'' * ''T. eufaulensis moorei'' * ''T. guildi'' * ''T. hemisphaerica'' * ''T. imbricata'' * ''T. interlaevigata'' * ''T. intersitans'' * ''T. kitchini'' * ''T. maastrichtiana'' * ''T. maloneana'' * ''T. marginata'' * ''T. mearnsi'' * ''T. montanaensis'' * ''T. orientalis'' * ''T. papuana'' * ''T. picteti'' * ''T. plana'' * ''T. pseudocaudata'' * ''T. pseudocrenulata'' * ''T. pullus'' * ''T. rebouli'' * ''T. reesidei'' * ''T. resoluta'' * ''T. reticulata'' * ''T. saavedra'' * ''T. semiculta'' * ''T. somaliensis'' * ''T. stantoni'' * ''T. stolleyi'' * ''T. suborbicularis'' * ''T. sulcata'' * ''T. taffi'' * ''T. thierachensis'' * ''T. undulatocostata'' * ''T. vyschetzkii'' * ''T. weaveri''

Distribution

Fossils of ''Trigonia'' have been registered in: ;Permian Bolivia ( Copacabana Formation) ;Triassic Austria, China, Italy, the Russian Federation, United States (Alaska, Idaho), and Vietnam. ;Jurassic Afghanistan, Argentina, Canada (Alberta, British Columbia, Yukon), Chile, Colombia (

Valle Alto Formation The Valle Alto Formation (, Jva) is a geological formation of the Central Ranges of the Colombian Andes. The formation is composed of shales, sandstones and conglomerates and dates to the Late Jurassic period. Ammonites and fossil flora have been ...

, Caldas),Mojica, 1984, p.132 Egypt, Ethiopia, France, Germany, Greenland, India, Iran, Japan, Kenya, Luxembourg, Madagascar, Morocco, New Zealand, Poland, Portugal, the Russian Federation, Saudi Arabia, Somalia, Spain, Tanzania, Thailand, Tunisia, the United Kingdom, United States (Alaska, California, Idaho, Montana, Nevada, Oregon, Texas, Utah, Wyoming), and Yemen. ;Cretaceous Afghanistan, Algeria, Antarctica, Argentina, Armenia, Australia, Brazil, Bulgaria, Canada (British Columbia), Chile, Colombia ( Yuruma Formation,

La Guajira La Guajira () is a departments of Colombia, department of Colombia. It occupies most of the Guajira Peninsula in the northeast region of the country, on the Caribbean Sea and bordering Venezuela, at the northernmost tip of South America. The ca ...

Macanal Formation The Macanal Formation or Macanal Shale (, Kilm, K1m) is a list of fossiliferous stratigraphic units of Colombia, fossiliferous formation (geology), geological formation of the Altiplano Cundiboyacense and Tenza Valley in the Cordillera Oriental (Co ...

Eastern Ranges The Eastern Ranges is an Australian rules football team that currently competes in the Talent League, the Victorian statewide under-18s competition. History Inaugural playing squad (1992) Honours *Premiers (2): 2002, 2013 *Runners-up (6): 199 ...

),Piraquive et al., 2011, p.204 Egypt, France, Germany, Greenland, Hungary, Italy, Lebanon, Mexico, the Netherlands, New Zealand, Papua New Guinea, Peru, Portugal, Serbia and Montenegro, South Africa, Spain, Switzerland, Tanzania, Turkmenistan, Russian Federation, Ukraine, the United Kingdom, United States (Arizona, California, Delaware, Mississippi, New Jersey, North Carolina, Tennessee, Texas), Venezuela, and Yemen. ;Paleocene Argentina ( Cerro Dorotea Formation)

References

Bibliography

* *

External links

Sepkoski's Online Genus Database
{{Taxonbar, from=Q38335712 Trigoniidae Paleozoic bivalves Permian animals of South America Permian Bolivia Mesozoic bivalves Mesozoic animals of Africa Mesozoic animals of Asia Mesozoic animals of Europe Mesozoic animals of Oceania Mesozoic animals of North America Mesozoic animals of South America Jurassic Argentina Cretaceous Argentina Cretaceous Brazil Jurassic Chile Cretaceous Chile Jurassic Colombia Cretaceous Colombia Fossils of Colombia Cretaceous Peru Cretaceous Venezuela Paleogene bivalves Paleogene animals of South America Paleogene Argentina Permian first appearances Paleocene genus extinctions Cretaceous–Paleogene boundary Fossil taxa described in 1789 Anisian life Prehistoric bivalve genera Fossils of Serbia