Ogallala opaline sandstone with Cremnoceramus deformis fragments 20201115 143032

''Cremnoceramus'' ("cremno-" = ''kremnos''

reek Reek may refer to: Places * Reek, Netherlands, a village in the Dutch province of North Brabant * Croagh Patrick, a mountain in the west of Ireland nicknamed "The Reek" People * Nikolai Reek (1890–1942), Estonian military commander * Salme Reek ...

precipice or over hanging wall or bank; "ceramus" = ''keramos''

clay pot) is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

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 ...

of fossil marine

pteriomorphia The Pteriomorphia comprise a subclass of saltwater clams, marine bivalve molluscs. It contains several major orders, including the Arcida, Ostreida, Pectinida, Limida, Mytilida, and Pteriida. It also contains some extinct and probably ...

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 ...

s that superficially resembled the related winged pearly oysters of the

extant Extant or Least-concern species, least concern is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Exta ...

genus '' Pteria''. They lived from the

Turonian The Turonian is, in the International Commission on Stratigraphy, ICS' geologic timescale, the second age (geology), age in the Late Cretaceous epoch (geology), Epoch, or a stage (stratigraphy), stage in the Upper Cretaceous series (stratigraphy), ...

to the

Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...

of the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

Description

''Cremnoceramus'' were facultatively mobile, blind,

suspension feeding Filter feeders are aquatic animals that acquire nutrients by feeding on organic matters, food particles or smaller organisms (bacteria, microalgae and zooplanktons) suspended in water, typically by having the water pass over or through a specia ...

bivalves with low-magnesium

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

shells. ''Inoceramids'', like the ''Cremnoceramus'' in particular, had thick shells composed of particular "prisms" of

deposited perpendicular to the surface, and unweathered fossils commonly preserve the mother-of-pearl luster the shells had in life. Compared to the many examples of broad and flattened ''Inoceramidae'', ''Cremnoceramus'' shells are rather "high-walled", deep bowl-shaped. The top shell is commonly encrusted with oysters.

Species

The following species are recognized: * ''C. crassus'' * ''C. deformis'' * ''C. inconstans'' * ''C. rotundatus'' * ''C. waltersdorfensis''

Biostratigraphic significance

The first appearance of the species '' Cremnoceramus rotundatus'' marks the beginning of the

Coniacian The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma (million years ago). The Coniacian is preceded by ...

stage.

Distribution

Fossils of the genus have been found in:''Cremnoceramus''
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 * Gosau Formation, Austria * Cotinguiba Formation, Brazil *

Pointe-Noire Pointe-Noire (; , with the letter d following French spelling standards) is the second largest city in the Republic of the Congo, following the capital of Brazzaville, and an autonomous department and a commune since the 2002 Constitution. B ...

, Congo-Brazzaville * Jicin, the Czech Republic * Arnager Limestone Formation, Denmark * Craie de Villedieu Formation, France * Germany * Anaipadi Formation, India * Tongobury, Madagascar * Austin Group, Mexico * Sant Corneli and El Zadorra Formation, Spain * Lewes Nodular Chalk Formation, the United Kingdom *

Niobrara Formation The Niobrara Formation , also called the Niobrara Chalk, is a geologic formation in North America that was deposited between 87 and 82 million years ago during the Coniacian, Santonian, and Campanian stages of the Late Cretaceous. It is com ...

, New Mexico, United States

Gallery

Note the oyster encrustation of the top shells: File:Fort Hays Limestone, Cremnoceramus deformis 20181124 153914.jpg, Horizontal section of articulated ''C. deformis'' (Fort Hays ls.) File:Fort Hays Limestone, Cremnoceramus deformis (Ft. Hays Blockhouse) 20160619 081653.jpg, Lateral section of articulated ''C. deformis'' (Fort Hays ls.) File:Fort Hays Limestone, Cremnoceramus deformis (FUMC) 20160619 071549.jpg, Lateral section of articulated ''C. deformis'' (Fort Hays ls.) File:Fort Hays Limestone, Cremnoceramus deformis (FUMC) 20160619 071713.jpg, Horizontal section of articulated ''C. deformis'' (Fort Hays ls.)

References

{{Reflist, 3 {{Taxonbar, from=Q104822798 Inoceramidae Prehistoric bivalve genera Index fossils Cretaceous Austria Fossils of Austria Cretaceous Brazil Fossils of Brazil Fossils of the Czech Republic Cretaceous Denmark Fossils of Denmark Cretaceous France Fossils of France Cretaceous Germany Fossils of Germany Cretaceous India Fossils of India Cretaceous Madagascar Fossils of Madagascar Cretaceous Mexico Fossils of Mexico Cretaceous Spain Fossils of Spain Cretaceous England Fossils of England Cretaceous geology of New Mexico Fossils of the United States Fossil taxa described in 1969