The Cretaceous is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of the entire Phanerozoic. The name is derived from the Latin creta, "chalk", which is abundant in the latter half of the period. It is usually abbreviated K, for its German translation Kreide.
Macrofossils, also known as megafossils, are preserved organic remains large enough to be visible without a microscope. The term macrofossil stands in opposition to the term microfossil. Microfossils, by contrast, require substantial magnification for evaluation by fossil-hunters or professional paleontologists. As a result, most fossils observed in the field and most "museum-quality" specimens are macrofossils.
Rudists are a group of extinct box-, tube- or ring-shaped marine heterodont bivalves belonging to the order Hippuritida that arose during the Late Jurassic and became so diverse during the Cretaceous that they were major reef-building organisms in the Tethys Ocean, until their complete extinction at the close of the Cretaceous.
Hippurites is an extinct genus of rudist bivalve mollusc from the Late Cretaceous of Africa, Asia, Europe, North America, and South America.
Polazzodus is an extinct pycnodontid from the late Cretaceous of the Polazzo locality of northeastern Italy. The paleoenvironment of Polazzo was a large marine carbonate platform and shallow internal lagoons formed from rudist reefs. P. coronatus is known from numerous specimens, many of which were very well-preserved.
The Garzan oil field is an oil field located in Batman, Batman Province, Southeastern Anatolia Region. It was discovered in 1947–1951 and developed by Türkiye Petrolleri Anonim Ortaklığı. It began production in 1956. The total proven reserves of the Garzan oil field are around 163 million barrels (22.2×106 tonnes), and production is about 1,700 barrels per day (270 m3/d). The structure is a double plunging anticline bordered by a major reverse fault extending along the southern flank. The age of the Garzan formation is cretaceous, consisting of carbonates of a rudist build-up complex. Oil field contains 24 degree API (0.91 g/cm3) oil with a reservoir viscosity of 6.75 cp. Reservoir was initially highly undersaturated lists basic reservoirdata for Garzan.
Caprina is a genus of rudists, a group of marine heterodont bivalves belonging to the family Caprinidae.
Requienia is an extinct genus of fossil saltwater clam, a marine bivalve molluscs in the order Hippuritida, family Requieniidae. These rudists lived in the Cretaceous period, from the Valanginian age (136.4–140.2) to the Campanian age. They were stationary intermediate-level suspension feeders.
The prehistory of the United States comprises the occurrences within regions now part of the United States during the interval of time spanning from the formation of the Earth to the documentation of local history in written form. At the start of the Paleozoic era, what is now "North" America was actually in the southern hemisphere. Marine life flourished in the country's many seas, although terrestrial life had not yet evolved. During the latter part of the Paleozoic, seas were largely replaced by swamps home to amphibians and early reptiles. When the continents had assembled into Pangaea drier conditions prevailed. The evolutionary precursors to mammals dominated the country until a mass extinction event ended their reign.
The Sierra Madre Formation is a geologic formation in Chiapas state, southern Mexico. It consists of marine dolomites and limestones. The formation dates to the Middle Cretaceous, spanning from the Aptian of the Early to the Cenomanian of the Late Cretaceous.
The Campur Formation (Kca) is a geologic formation of the Petén Basin of northern Guatemala. The subtidal limestone preserves fossils dating back to the Late Cretaceous period.
The Habana Formation is a geologic formation in Cuba. It preserves mainly gastropod and rudist fossils dating back to the Late Campanian to Maastrichtian periods. The formation was defined by Robert H. Palmer in 1934.
The Peters Hill Limestone or Peters Hill Formation is a geologic formation in Jamaica. It preserves fossils such as rudists, echinoids and corals from the Santonian stage of the Cretaceous Period.
The Cretaceous–Paleogene (K–Pg) extinction event was a sudden mass extinction of three-quarters of the plant and animal species on Earth, approximately 66 million years ago. With the exception of some ectothermic species such as sea turtles and crocodilians, no tetrapods weighing more than 25 kilograms survived. It marked the end of the Cretaceous Period, and with it the Mesozoic era, while heralding the beginning of the Cenozoic era, which continues to this day.
The island of Curaçao began to form within the past 145 million years, beginning in the Cretaceous, as part of the Lesser Antilles island arc. Because the island was submerged for large parts of its history, reef environments formed atop thick layers of mafic volcanic rock, producing carbonate sedimentary rocks.
Darwin Guyot is a volcanic underwater mountain top, or guyot, in the Mid-Pacific Mountains between the Marshall Islands and Hawaii. Named after Charles Darwin, it rose above sea level more than 118 million years ago during the early Cretaceous period to become an atoll, developed rudist reefs, and then drowned, perhaps as a consequence of sea level rise. The flat top of Darwin Guyot now rests 1,266 metres (4,154 ft) below sea level.
Takuyo-Daini is a seamount in the Pacific Ocean.
Radiolites is a genus of rudists in the family Radiolitidae.
The Calcare di Bari is a Cretaceous geologic formation in Apulia, southeastern Italy. The formation comprises micritic limestones, in places karstified and dolomitized. Rudists and fossil ankylosaur, sauropod and theropod tracks have been reported from the 2,000 metres (6,600 ft) thick formation that was deposited in an inner carbonate platform environment towards the top dominated by rudist reefs.
