| Amphorosteus Temporal range: Late Cretaceous | |
|---|---|
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | Squamata |
| Superfamily: | † Mosasauroidea |
| Family: | † Mosasauridae |
| Genus: | † Amphorosteus Gibbs, 1851 |
| Type species | |
| †Amphorosteus brumbyi Gibbs, 1851 | |
Amphorosteus is a dubious genus of mosasaur from the Late Cretaceous of North America. It was described on the basis of two, heavily weathered vertebrae unearthed from Alabama. [1]
Mosasaurs comprise a group of extinct, large marine reptiles from the Late Cretaceous. Their first fossil remains were discovered in a limestone quarry at Maastricht on the Meuse in 1764. They belong to the order Squamata, which includes lizards and snakes.
Mosasaurus is the type genus of the mosasaurs, an extinct group of aquatic squamate reptiles. It lived from about 82 to 66 million years ago during the Campanian and Maastrichtian stages of the Late Cretaceous. The earliest fossils of Mosasaurus known to science were found as skulls in a chalk quarry near the Dutch city of Maastricht in the late 18th century, which were initially thought to have been the bones of crocodiles or whales. One skull discovered around 1780, which was seized by France during the French Revolutionary Wars for its scientific value, was famously nicknamed the "great animal of Maastricht". In 1808, naturalist Georges Cuvier concluded that it belonged to a giant marine lizard with similarities to monitor lizards but otherwise unlike any known living animal. This concept was revolutionary at the time and helped support the then-developing ideas of extinction. Cuvier did not designate a scientific name for the new animal, and this was done by William Daniel Conybeare in 1822 when he named it Mosasaurus in reference to its origin in fossil deposits near the Meuse River. The exact affinities of Mosasaurus as a squamate remain controversial, and scientists continue to debate whether its closest living relatives are monitor lizards or snakes.
Selmasaurus is an extinct genus of marine lizard belonging to the mosasaur family. It is classified as part of the Plioplatecarpinae subfamily alongside genera like Angolasaurus and Platecarpus. Two species are known, S. russelli and S. johnsoni; both are exclusively known from Santonian deposits in the United States.
The Mosasaurinae are a subfamily of mosasaurs, a diverse group of Late Cretaceous marine squamates. Members of the subfamily are informally and collectively known as "mosasaurines" and their fossils have been recovered from every continent except for South America.
Eonatator is an extinct genus of marine lizard belonging to the mosasaur family. It is a close relative of Halisaurus, and part of the same subfamily, the Halisaurinae. It is known from the Late Cretaceous of North America, Colombia and Sweden. Originally, this taxon was included within Halisaurus, but was placed in its own genus, which also led to the subfamily Halisaurinae being created for the two genera.
Platecarpus is an extinct genus of aquatic lizards belonging to the mosasaur family, living around 84–81 million years ago during the middle Santonian to early Campanian, of the Late Cretaceous period. Fossils have been found in the United States and possible specimens in Belgium and Africa. A well-preserved specimen of Platecarpus shows that it fed on moderate-sized fish, and it has been hypothesized to have fed on squid, and ammonites as well. Like other mosasaurs, it was initially thought to have swum in an eel-like fashion, although another study suggests that it swam more like modern sharks. An exceptionally well-preserved specimen of P. tympaniticus known as LACM 128319 shows skin impressions, pigments around the nostrils, bronchial tubes, and the presence of a high-profile tail fluke, showing that it and other mosasaurs did not necessarily have an eel-like swimming method, but were more powerful, fast swimmers. It is held in the Natural History Museum of Los Angeles County. Isotopic analysis on teeth specimens has suggested that this genus and Clidastes may have entered freshwater occasionally, just like modern sea snakes.
Globidens is an extinct genus of mosasaur lizard classified as part of the Globidensini tribe in the Mosasaurinae subfamily.
Protostega is an extinct genus of sea turtle containing a single species, Protostega gigas. Its fossil remains have been found in the Smoky Hill Chalk formation of western Kansas, time-equivalent beds of the Mooreville Chalk Formation of Alabama and Campanian beds of the Rybushka Formation. Fossil specimens of this species were first collected in 1871, and named by Edward Drinker Cope in 1872. With a total length of 3.9 metres (13 ft), it is the second-largest sea turtle that ever lived, second only to the giant Archelon, and one of the three largest turtle of all time along Archelon and Gigantatypus.
Clidastes is an extinct genus of marine lizard belonging to the mosasaur family. It is classified as part of the Mosasaurinae subfamily, alongside genera like Mosasaurus and Prognathodon. Clidastes is known from deposits ranging in age from the Coniacian to the early Campanian in the United States.
The Mooreville Chalk is a geological formation in North America, within the U.S. states of Alabama and Mississippi, which were part of the subcontinent of Appalachia. The strata date back to the early Santonian to the early Campanian stage of the Late Cretaceous. The chalk was formed by pelagic sediments deposited along the eastern edge of the Mississippi embayment. It is a unit of the Selma Group and consists of the upper Arcola Limestone Member and an unnamed lower member. Dinosaur, mosasaur, and primitive bird remains are among the fossils that have been recovered from the Mooreville Chalk Formation.
The Demopolis Chalk is a geological formation in North America, within the U.S. states of Alabama, Mississippi, and Tennessee. The chalk was formed by pelagic sediments deposited along the eastern edge of the Mississippi embayment during the middle Campanian stage of the Late Cretaceous. It is a unit of the Selma Group and consists of the upper Bluffport Marl Member and a lower unnamed member. Dinosaur and mosasaur remains are among the fossils that have been recovered from the Demopolis Chalk.
The Selma Group is a geological formation in North America, within the U.S. states of Alabama, Mississippi, and Tennessee. The strata date from the Santonian to the Maastrichtian stages of the Late Cretaceous. The group is composed of, in ascending order, the Mooreville Chalk Formation, Demopolis Chalk Formation, Ripley Formation, and Prairie Bluff Chalk Formation. Dinosaur and mosasaur remains are among the fossils that have been recovered from the Selma Group.
The Eutaw Formation is a geological formation in North America, within the U.S. states of Alabama, Georgia, and Mississippi. The strata date from the late Coniacian to the early Santonian stage of the Late Cretaceous. It consists of the upper Tombigbee Sand Member and an unnamed lower member. Dinosaur, mosasaur, and pterosaur remains have been recovered from the Eutaw Formation.
The Ripley Formation is a geological formation in North America found in the U.S. states of Alabama, Georgia, Mississippi, Missouri, and Tennessee. The lithology is consistent throughout the layer. It consists mainly of glauconitic sandstone. It was formed by sediments deposited during the Maastrichtian stage of the Late Cretaceous. It is a unit of the Selma Group and consists of the Cusseta Sand Member, McNairy Sand Member and an unnamed lower member. It has not been extensively studied by vertebrate paleontologists, due to a lack of accessible exposures. However, fossils have been unearthed including crocodile, hadrosaur, nodosaur, tyrannosaur, ornithomimid, dromaeosaur, and mosasaur remains have been recovered from the Ripley Formation.
The Hornerstown Formation is a Paleogene or latest Mesozoic geologic formation in New Jersey. The age of these deposits have been controversial. While most fossils are of animals types known from the earliest Cenozoic era, several fossils of otherwise exclusively Cretaceous age have been found. These include remains of the shark Squalicorax, several types of non-avian dinosaurs, the teleost fish Enchodus, several species of ammonite, and marine lizards referred to the genus Mosasaurus. Some of these remains show signs of severe abrasion and erosion, however, implying that they are probably re-worked from older deposits. Most of these fossils are restricted to the lowest point in the formation, one rich in fossils and known as the Main Fossiliferous Layer, or MFL. Other explanations for the out-of-place fossils in the MFL is that they represent a time-averaged assemblage that built up and remained unburied during a time of low sediment deposition, or that they were stirred up from deeper in the sediment and deposited together during a tsunami.
Paleontology in Mississippi refers to paleontological research occurring within or conducted by people from the U.S. state of Mississippi. The oldest rocks in Mississippi date back to the Late Devonian. At the time, the northeastern part of the state was covered in a sea where brachiopods, crinoids, and trilobites lived. Remains of contemporary local plants also ended up preserved in this environment. During the Late Carboniferous, Mississippi became part of a richly-vegetated coastal plain environment. There are no rocks dating to the Permian, Triassic, or Jurassic in the state. However, during the Cretaceous, evidence suggests that the state was covered by a sea home to cephalopods, mosasaurs and sharks. Local trees left behind petrified wood and amber. By the Cenozoic, only the southern half of the state was covered in seawater, where the early whale Basilosaurus lived. On land, trees that were home to some of the earliest known primates left behind petrified wood. For the remainder of the Cenozoic, the state's climate cooled. Many fossils have been serendipitously discovered in the state by people looking for fossil fuels. Significant fossil finds in Mississippi include some of the oldest known primate fossils. The Eocene whales Basilosaurus cetoides and Zygorhiza kochii are the Mississippi state fossils.
This timeline of mosasaur research is a chronologically ordered list of important fossil discoveries, controversies of interpretation, and taxonomic revisions of mosasaurs, a group of giant marine lizards that lived during the Late Cretaceous Epoch. Although mosasaurs went extinct millions of years before humans evolved, humans have coexisted with mosasaur fossils for millennia. Before the development of paleontology as a formal science, these remains would have been interpreted through a mythological lens. Myths about warfare between serpentine water monsters and aerial thunderbirds told by the Native Americans of the modern western United States may have been influenced by observations of mosasaur fossils and their co-occurrence with creatures like Pteranodon and Hesperornis.
Calcarichelys is an extinct genus of protostegid turtle from the Late Cretaceous of the Selma Formation in Alabama, and possibly from Angola. It contains only one species, C. gemma.
 | This article about a prehistoric lizard is a stub. You can help Wikipedia by expanding it. |
 | This article about a Cretaceous reptile is a stub. You can help Wikipedia by expanding it. |
