Inoceramus

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Inoceramus
Temporal range: Early Jurassic-Maastrichtian
~189–66  Ma
Inocerame (Inoceramus cycloides colossus), exposition Un T-Rex a Paris, Museum national d'histoire naturelle.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Bivalvia
Order: Pteriida
Family: Inoceramidae
Genus: Inoceramus
Sowerby, 1814
Species

See text

Inoceramus (Greek: translation "strong pot") is an extinct genus of fossil marine pteriomorphian bivalves that superficially resembled the related winged pearly oysters of the extant genus Pteria . They lived from the Early Jurassic to latest Cretaceous. [1] [2]

Contents

Taxonomy

The taxonomy of the inoceramids is disputed, with genera such as Platyceramus sometimes classified as subgenus within Inoceramus. Also the number of valid species in this genus is disputed.

Description

Sphenoceramus steenstrupi.jpg
Inoceramus steenstrup, world's largest fossil mollusk.jpg
Halves of a gigantic specimen of I. steenstrupi 187 cm (74 in) across, found on the Nuussuaq Peninsula, Greenland
Weathered shell fragment of the closely related Cremnoceramus difformis, highlighting the orientation and texture of the calcite prisms of the Inoceramids. Ogallala opaline sandstone with Cremnoceramus deformis fragments 20201115 143032.jpg
Weathered shell fragment of the closely related Cremnoceramus difformis, highlighting the orientation and texture of the calcite prisms of the Inoceramids.

Inoceramids had thick shells composed of "prisms" of calcite deposited perpendicular to the surface, and unweathered fossils commonly preserve the mother-of-pearl luster the shells had in life. [3] Most species have prominent growth lines which appear as raised semicircles concentric to the growing edge of the shell. [3]

In 1952, the huge specimen of Inoceramus steenstrupi 187 cm long, was found in Qilakitsoq, the Nuussuaq Peninsula, Greenland. This fossil is 83 Ma old, the Upper Santonian or Lower Campanian stage. [4] Paleontologists suggest that the giant size of some species was an adaptation for life in the murky bottom waters, with a correspondingly large gill area that would have allowed the animal to survive in oxygen-deficient waters. [3]

Selected species

Distribution

The Western Interior Seaway that covered North America during the Cretaceous Map of North America with the Western Interior Seaway during the Campanian (Upper Cretaceous).png
The Western Interior Seaway that covered North America during the Cretaceous

Species of Inoceramus had a worldwide distribution during the Cretaceous and Jurassic periods (from 189.6 to 66.043 Ma). [1] Many examples are found in the Pierre Shale of the Western Interior Seaway in North America. Inoceramus can also be found abundantly in the Cretaceous Gault Clay that underlies London. Other locations for this fossil include Vancouver Island, [3] British Columbia, Colombia (Hiló Formation, Tolima and La Frontera Formation, Boyacá, Cundinamarca and Huila), [6] Spain, France, Germany, Afghanistan, Albania, Algeria, Angola, Antarctica, Argentina, Australia, Austria, Brazil, Bulgaria, Canada (Alberta, Northwest Territories, Nunavut, Saskatchewan, Yukon), Chile, China, Cuba, the Czech Republic, Denmark, Ecuador, Egypt, Hungary, India, Indian Ocean, Iran, Italy, Jamaica, Japan, Jordan, Kenya, Libya, Madagascar, Mexico, Morocco, Mozambique, Nepal, New Caledonia, New Zealand, Nigeria, Papua New Guinea, Peru, Poland, the Russian Federation, Saudi Arabia, Serbia and Montenegro, South Africa, Sweden, Switzerland, Tunisia, Turkey, Turkmenistan, the United Kingdom, United States (Alabama, Alaska, Arizona, Arkansas, California, Colorado, Delaware, Idaho, Iowa, Kansas, Maryland, Minnesota, Mississippi, Montana, Nebraska, New Jersey, New Mexico, North Carolina, North Dakota, Oregon, South Carolina, South Dakota, Tennessee, Texas, Utah, Washington, Wyoming), and Venezuela. [1]

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References

  1. 1 2 3 Inoceramus Archived 17 November 2022 at the Wayback Machine at Fossilworks.org
  2. Ward et al., "Ammonite and inoceramid bivalve extinction patterns in Cretaceous/Tertiary boundary sections of the Biscay region (southwestern France, northern Spain)", Geology , 1991
  3. 1 2 3 4 Ludvigsen & Beard, 1997, pp. 102–103
  4. "Verdens største musling". 5 March 2020. Archived from the original on 18 August 2022.
  5. Roemer, F. (1849). Texas : mit besonderer Rücksicht auf deutsche Auswanderung und die physischen Verhältnisse des Landes nach eigener Beobachtung. A. Marcus.
  6. Acosta & Ulloa, 2001, p. 41

Bibliography

Further reading