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 genus was one of the first Mesozoic marine reptiles known to science—the first fossils of Mosasaurus were found as skulls in a chalk quarry near the Dutch city of Maastricht in the late 18th century, and were initially thought to be 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.
Tylosaurus is a genus of mosasaur, a large, predatory marine reptile closely related to modern monitor lizards and to snakes, from the Late Cretaceous.
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.
The Tylosaurinae are a subfamily of mosasaurs, a diverse group of Late Cretaceous marine squamates. Members of the subfamily are informally and collectively known as "tylosaurines" and have been recovered from every continent except for South America. The subfamily includes the genera Tylosaurus, Taniwhasaurus, and Kaikaifilu, although some scientists argue that only Tylosaurus and Taniwhasaurus should be included.
The Halisaurinae are a subfamily of mosasaurs, a group of Late Cretaceous marine lizards. They were small to medium-sized, ranging from just under 3 meters in Eonatator sternbergi to as much as 8 or 9 meters in Pluridens serpentis. They tended to have relatively slender jaws and small, numerous teeth, suggesting a diet of small fish and other prey. Although the skeleton is primitive compared to other Mosasauridae in many respects, halisaurines had the distinctive hypocercal tail of other mosasaurids suggesting good swimming ability, and they persisted alongside other mosasaurs until the end of the Cretaceous. The earliest known remains of halisaurines occur in rocks of Santonian age and the subfamily persists until the latest Maastrichtian. Halisaurines are known from North and South America, Europe, Asia and Africa, indicating a more or less global distribution in the Late Cretaceous. Four genera are currently recognized: Eonatator, Halisaurus, Phosphorosaurus and Pluridens.
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.
Globidens is an extinct genus of mosasaurid oceanic lizard classified as part of the Globidensini tribe in the Mosasaurinae subfamily.
Prognathodon 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 Clidastes. Prognathodon has been recovered from deposits ranging in age from the Campanian to the Maastrichtian in the Middle East, Europe, New Zealand, and North America.
Halisaurus is an extinct genus of marine reptile belonging to the mosasaur family. The holotype, consisting of an angular and a basicranium fragment discovered near Hornerstown, New Jersey, already revealed a relatively unique combination of features and prompted a new genus to be described. It was named by Othniel Charles Marsh in 1869 and means "ocean lizard". It was renamed by Marsh to Baptosaurus in 1870, since he believed the name to already be preoccupied by the fish Halosaurus. According to modern rules, a difference of a letter is enough and the substitute name is unneeded, making "Baptosaurus" a junior synonym.
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.
Goronyosaurus is an extinct genus of marine lizard belonging to the mosasaur family. Fossils of Goronyosaurus are exclusively known from the Late Maastrichtian of the Iullemmeden Basin in West Africa, specifically the Dukamaje Formation of Niger and Nigeria and Farin Doutchi Formation of Niger. The type specimen was first described in 1930 as Mosasaurus nigeriensis, but subsequent remains revealed a highly unique set of adaptations that prompted the species to be reclassified as the only species of the new genus Goronyosaurus in 1972. These unique adaptations have made Goronyosaurus notoriously difficult to classify within the Mosasauridae and it is often left out of phylogenetic analyses, although most authors agree that Goronyosaurus belonged to Mosasauridae.
Liodon is a dubious genus of mosasaur from the Late Cretaceous, known from fragmentary fossils discovered in St James' Pit, England and possibly also the Ouled Abdoun Basin of Morocco. Though dubious and of uncertain phylogenetic affinities, Liodon was historically a highly important taxon in mosasaur systematics, being one of the genera on which the family Mosasauridae was based.
Igdamanosaurus, meaning "lizard from Igdaman", is an extinct genus of Cretaceous marine lizard belonging to the mosasaur family. It is classified as part of the Globidensini tribe, and is like the other members of the tribe recognised by its rounded and knob-like teeth. These teeth indicate a highly specialized lifestyle, likely including a durophagous diet.
Angolasaurus is an extinct genus of mosasaur. Definite remains from this genus have been recovered from the Turonian and Coniacian of Angola, and possibly the Coniacian of the United States, the Turonian of Brazil, and the Maastrichtian of Niger. While at one point considered a species of Platecarpus, recent phylogenetic analyses have placed it between the (then) plioplatecarpines Ectenosaurus and Selmasaurus, maintaining a basal position within the plioplatecarpinae.
Phosphorosaurus is an extinct genus of marine lizard belonging to the mosasaur family. Phosphorosaurus is classified within the Halisaurinae subfamily alongside the genera Pluridens, Eonatator, and Halisaurus.
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.
Xenodens is an extinct genus of marine lizard belonging to the mosasaur family. It currently contains a single species, X. calminechari, which is known from Late Maastrichtian phosphate deposits in the Ouled Abdoun Basin, Morocco. Its closest known relative is believed to be the durophagous Carinodens.
Thalassotitan is an extinct genus of large mosasaurs that lived during the late Maastrichtian of the Cretaceous period in what is now Morocco, around 66 million years ago. The only known species is T. atrox, described in 2022 from fossils discovered in the Ouled Abdoun Basin, where many other mosasaurs have been found. It was assigned to the tribe Prognathodontini alongside other mosasaurs like Prognathodon and Gnathomortis. The prognathodontines are separated from other mosasaurs based on their massive jaws and robust teeth.
