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
Halves of a gigantic specimen of I. steenstrupi 187 cm (74 in) across, found on the
Nuussuaq Peninsula, Greenland
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]
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),[5] 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]
Kennedy, W.J.; Kauffman, E.G.; Klinger, H.C. (1973). "Upper Cretaceous Invertebrate Faunas from Durban, South Africa". Geological Society of South Africa Transactions. 76 (2): 95–111.
Klinger, H.C.; Kennedy, W.J. (1980). "Upper Cretaceous ammonites and inoceramids from the off-shore Alphard Group of South Africa". South African Museum. 82 (7): 293–320.
Gebhardt, H. (2001). "Inoceramids, Didymotis and ammonites from the Nkalagu Formation type locakity (late Turonian to Coniacian, southern Nigeria): biostratigraphy and palaeoecologic implications". Neues Jahrbuch für Geologie und Paläontologie, Monatshefte. 2001 (4): 193–212.
doi:
10.1127/njgpm/2001/2001/193.
El Qot, G.M. (2006). "Late Cretaceous macrofossils from Sinai, Egypt". Beringeria. 36: 3–163.
Wild, T. J.; Stilwell, J. D. (2016). "First Cretaceous (Albian) invertebrate fossil assemblage from Batavia Knoll, Perth Abyssal Plain, eastern Indian Ocean: taxonomy and paleoecological significance". Journal of Paleontology. 90 (5): 959–980.
Bibcode:
2016JPal...90..959W.
doi:
10.1017/jpa.2016.76.
External links
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