Ammonoids are extinct spiral shelled cephalopods comprising the subclass Ammonoidea. They are more closely related to living coleoids than they are to shelled nautiloids. The earliest ammonoids appeared during the Devonian, with the last species vanishing during or soon after the Cretaceous–Paleogene extinction event. They are often called ammonites, which is most frequently used for members of the order Ammonitida, the only living group of ammonioids from the Jurassic up until their extinction.
Baculites is an extinct genus of heteromorph ammonite cephalopods with almost straight shells. The genus, which lived worldwide throughout most of the Late Cretaceous, and which briefly survived the K-Pg mass extinction event, was named by Lamarck in 1799.
The Maastrichtian is, in the ICS geologic timescale, the latest age of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval from 72.1 to 66 million years ago. The Maastrichtian was preceded by the Campanian and succeeded by the Danian.
The Danian is the oldest age or lowest stage of the Paleocene Epoch or Series, of the Paleogene Period or System, and of the Cenozoic Era or Erathem. The beginning of the Danian is at the Cretaceous–Paleogene extinction event 66 Ma. The age ended 61.6 Ma, being followed by the Selandian.
The Paleocene, or Palaeocene, is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name is a combination of the Ancient Greek παλαιός palaiós meaning "old" and the Eocene Epoch, translating to "the old part of the Eocene".
Pachydiscus is an extinct genus of ammonite from the Late Cretaceous and Early Paleocene with a worldwide distribution, and type for the desmoceratacean family Pachydiscidae. The genus' type species is P. neubergicus. Altogether some 28 species have been described.
The Maastricht Formation, named after the city of Maastricht in the Netherlands, is a geological formation in the Netherlands and Belgium whose strata date back to the Late Cretaceous, within 500,000 years of the Cretaceous–Paleogene boundary, now dated at 66 million years ago. The formation is part of the Chalk Group and is between 30 and 90 metres thick. It crops out in southern parts of Dutch and Belgian Limburg and adjacent areas in Germany. It can be found in the subsurface of northern Belgium and southeastern Netherlands, especially in the Campine Basin and Roer Valley Graben. Dinosaur remains are among the fossils that have been recovered from the formation.
The Lopez de Bertodano Formation is a geological formation in the James Ross archipelago of the Antarctic Peninsula. The strata date from the end of the Late Cretaceous to the Danian stage of the lower Paleocene, from about 70 to 65.5 million years ago, straddling the Cretaceous-Paleogene boundary.
Discoscaphites is an extinct genus of ammonite. This genus may have been one of the few to have briefly survived the K-Pg mass extinction.
Hoploscaphites is an extinct ammonite genus from the Upper Cretaceous and the Lower Paleocene, included in the family Scaphitidae.
Sphenodiscus is an extinct genus of acanthoceratacean ammonite. The genus has been found from many continents and is thought to have had a large global distribution during the Maastrichtian stage of the Late Cretaceous. It was one of the last ammonoids to have evolved before the entire subclass became extinct during the Paleocene, which was directly after the Cretaceous–Paleogene extinction event.
Qinornis is a prehistoric bird genus from the early-mid-Paleocene epoch, about 61 million years ago. It is known from a single fossil specimen consisting of a partial hind limb and foot, which was found in Fangou Formation deposits in Luonan County, China.
Stevns Klint, known as the Cliffs of Stevns in English, is a white chalk cliff located some 6 km (3.7 mi) southeast of Store Heddinge on the Danish island of Zealand. Stretching 17 km (11 mi) along the coast, it is of geological importance as one of the best exposed Cretaceous-Tertiary (K/T) boundaries in the world. Subject to frequent erosion, the cliff rises to a height of up to 40 m (130 ft). Because of its exceptional fossil record, Stevens Klint was inscribed on the UNESCO World Heritage List in 2014.
Isocrania is an extinct genus of brachiopods found during the Upper Cretaceous. Early representatives were attached to the underground, but later species are presumed to be free living at an increasingly earlier age. This was probably an adaptation to the increasing very thick and fine sedimentation during the latest Cretaceous.
The Cretaceous–Paleogene (K–Pg) extinction event, also known as the Cretaceous–Tertiary(K–T)extinction, was a sudden mass extinction of three-quarters of the plant and animal species on Earth, approximately 66 million years ago. The event caused the extinction of all non-avian dinosaurs. Most other tetrapods weighing more than 25 kilograms also became extinct, with the exception of some ectothermic species such as sea turtles and crocodilians. 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 Globidensini or Globidentatini are a tribe of mosasaurine mosasaurs, a diverse group of Late Cretaceous marine squamates. Members of the tribe, known as "globidensins" or "globidensine mosasaurs", have been recovered from North America, Europe, Africa and Asia. The tribe contains the genera Globidens, Carinodens, Igdamanosaurus, Harranasaurus and Xenodens. Features of the maxilla and digits make the placement of Carinodens and Xenodens in the tribe uncertain; some researchers have suggested that they may be more appropriately placed in the Mosasaurini.
The Jagüel Formation is a geological formation, located in Patagonia, Argentina. It underlies the Roca Formation and overlies the Allen Formation. All of these formations belong to the Malargüe Group. Its name was coined by Windhausen in 1914. This unit, defined in the eastern area of the Neuquén Embayment, registers an event of marine flooding that happened during the ages Maastrichtian and Danian. It consists of mudrocks formed between the upper section or "Gypsum" of the Allen Formation, and the base of the first organogenic limestone of the Roca Formation. The Jagüel Formation is particularly important since a vast area of the formation contains the Cretaceous–Paleogene boundary that marks the end of the Mesozoic Era. It also shows evidence of the Cretaceous–Paleogene (K–Pg) extinction event. In this period of time, animal species became extinct, such as non–avian dinosaurs, the last marine reptiles, ammonites, and many groups of microfossils.
The term Paleocene ammonites describes families or genera of Ammonoidea that may have survived the Cretaceous–Paleogene extinction event, which occurred 66.043 million years ago. Although almost all evidence indicated that ammonites did not survive past the K–Pg boundary, there is some scattered evidence that some ammonites lived for a short period of time during the Paleocene epoch, although none survived the Danian ; they were likely extinct within 500,000 years of the K-Pg extinction event, which correlates to roughly 65.5 Ma. The evidence for Paleocene ammonoids is rare and remains controversial.
The Rødvig Formation is a geological formation deposited during the earliest part of the Danian and it was first identified by Richard Taylor and Richard Phillips in 1827. It is known from exposures at Stevns Klint in Denmark. The unit lies directly above the K–Pg boundary and contains fossils that provide a record of the recovery of various groups following the Cretaceous–Paleogene extinction. The upper boundary of the formation is an unconformity in the form of a hardground, beneath which the formation is sometimes missing. The base of the unit is irregular due to the presence of mounding associated with bryozoa, causing variations in thickness. The unit is subdivided into the lower Fiskeler Member mainly formed of marl and the overlying Cerithium Limestone Member.
