Rudists
From Wikipedia, the free encyclopedia
Rudists Fossil range: Jurassic to Late Cretaceous |
||||||||||
---|---|---|---|---|---|---|---|---|---|---|
Rudist fossil
|
||||||||||
Scientific classification | ||||||||||
|
||||||||||
Families | ||||||||||
|
Rudists are a group of bizarrely shaped marine heterodont bivalves that arose during the Jurassic, and became so diverse during the Cretaceous that they were major reef-building organisms in the Tethys Ocean. The Jurassic forms were elongate, with both valves being similarly shaped, often pipe or stake-shaped, while the reef-building forms of the Cretaceous had one valve become a flat lid, with the other valve becoming an inverted spike-like cone. They were among the many animal groups that perished during the Cretaceous–Tertiary extinction event .
The rudists are, according to different systematic schemes, placed in the orders Hippuritoida or Rudistes (sometimes Rudista). Their "classic" morphology consisted of a lower, roughly conical valve that was attached to the seafloor or to neighboring rudists, and a smaller upper valve that served as a kind of lid for the organism.
Their classification as true reef-builders is controversial, yet they were one of the most important constituents of reefs during the Cretaceous period.[1] At one point, rudist reefs fringed the North American coast from the Gulf of Mexico to the present-day Maritime Provinces. Because of their high porosity, rudist reefs are highly-favored oil traps.
[edit] See also
[edit] References
- "An Introduction to the Paleontology of Rudist Bivalves." (Accessed 7/2/06)
- Paleos.com: "The Aptian Age" (info on rudists) (Accessed 7/2/06)
This mollusc-related article is a stub. You can help Wikipedia by expanding it. |