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.
The scientific study of mosasaurs began in the late 18th century with the serendipitous discovery of a large fossilized skeleton in a limestone mine near Maastricht in the Netherlands. The fossils were studied by local scholar Adriaan Gilles Camper, who noted a resemblance to modern monitor lizards in correspondence with renowned French anatomist Georges Cuvier. Nevertheless, the animal was not scientifically described until the English Reverend William Daniel Conybeare named it Mosasaurus, after the river Meuse located near the site of its discovery.
By this time the first mosasaur fossils from the United States were discovered by the Lewis and Clark Expedition, and the first remains in the country to be scientifically described were reported slightly later from New Jersey. This was followed by an avalanche of discoveries by the feuding Bone War paleontologists Edward Drinker Cope and Othniel Charles Marsh in the Smoky Hill Chalk of Kansas. By the end of the century a specimen of Tylosaurus would be found that preserved its scaley skin. Later Samuel Wendell Williston mistook fossilized tracheal rings for the remains of a fringe of skin running down the animal's back, which subsequently became a common inaccuracy in artistic restorations.
The 20th century soon saw the discovery in Alabama of a strange mosasaur called Globidens, with rounded teeth suited to crushing shells. Mosasaur remains were also discovered in Africa and California. In 1967 Dale Russell published a scientific monograph dedicated to mosasaurs. Embryonic remains in the 1990s confirmed that mosasaurs gave live birth like in ichthyosaurs. The 1990s also saw a revival and escalation of a debate regarding whether or not some supposed mosasaur toothmarks in ammonoid shells were actually made by limpets. By the end of the century, the evolutionary relationship between mosasaurs and snakes as well as the possible involvement of mosasaurs in the extinction of the aforementioned ichthyosaurs became hot button controversies.
The debates regarding snakes, toothmarks, and ichthyosaurs spilled over into the early 21st century. These discussions were also accompanied by the discovery of many new taxa, including new species of Globidens, Mosasaurus, and Tylosaurus as well as entirely new genera like Yaguarasaurus and Tethysaurus. In 2013, Lindgren, Kaddumi, and Polcyn reported the discovery of a Prognathodon specimen from Jordan that preserved the soft tissues of its scaley skin, flippers and tail. Significantly, the tail resembled those of modern carcharinid sharks, although the bottom lobe of the tail fin was longest in the mosasaur whereas shark tails have longer upper lobes.
Prescientific
One legend told among the Lenape (Delaware) people describes the discovery of a fragment of bone left by a monster that had once been killing people near modern Philadelphia in either Pennsylvania or eastern New Jersey. When the hunting party brought the piece of bone back to the village, a wise man encouraged them to set out and find more of the monsters remains. He said that smoking fragments of the bone with tobacco in a small clay spoon could grant wishes like good health for one's children, longevity, or successful hunting. Fossils of the mosasaur Tylosaurus have been found in the area, but dinosaurs and Cretaceous crocodiles are also possible sources. This legend likely predates European contact and may have originated prior to 1500. The bones being burnt in the "clay spoon" is a reference to a primitive kind of clay pipe that the local people had abandoned in favor of a design with a deeper bowl by the 17th century. The general lack of any sign of influence by European culture on the tale is also suggestive of its great antiquity. The Cheyenne people of Nebraska believed in mythical thunderbirds and water monsters that were in endless conflict with each other. The thunderbirds were said to resemble giant eagles and killed both people and animals with arrows made of lightning. The fossils of the Niobrara Chalk may have been influential on these stories. The pterosaur Pteranodon and marine reptiles like mosasaurs are preserved in Niobrara Chalk deposits and associated remains may have been interpreted as evidence for antagonism between immense flying animals and serpentine aquatic reptiles. Observations of similar fossils in the past may have been seen as further evidence for thunderbird-water monster conflict.
The Cheyenne believe that there were many different kinds of water monsters that lived not only in lakes, rivers, and springs but also high bluffs and hills. The locations given as water monster habitat are similar to the locations where local marine fossils can be found as fossils often erode out of hillsides or stream banks. The Cheyennes feared the water monsters, because they could be dangerous predators or capsize their canoes. Even in modern times, tradition-minded Cheyenne sometimes take pains to avoid sleeping too close to springs due to fears of water monsters.
The Crow people also believed in water monsters. These were said to be alligator-like creatures living in the Little Bighorn, Rosebud, and Tongue Rivers. These myths may have been based on discoveries of marine reptile fossils such as mosasaurs and crocodilians eroding out of the river banks. The Crow also believe there were similar alligator-like monsters in the Missouri River. These were called Bulukse'e or Buruksam Wurukce, names meaning "large meat-eater" but commonly translated as "giant lizard or alligator". When the Sioux people lived around the Great Lakes, they imagined their mythical Water Monster Unktehi as a large aquatic buffalo-like mammal. This image was likely derived from early observations of large Pleistocene mammal fossils such as mammoths and mastodons eroding out of the banks of local lakes and rivers. As some groups of Sioux began moving west into the regions that includes Montana their depictions of Unktehi tended to converge on the characteristics of local fossils. Although Unktehi continued to be described as horned, it gradually became imagined as reptilian rather than the mammalian portrayals of the Sioux in the Great Lakes region, like the dinosaurs and mosasaurs of the region's Mesozoic rock. Unktehi was described as a snakelike monster equipped with feet, like the elongate sinuous mosasaurs who had four short limbs. Its back was described as ridged and saw-like, a configuration similar to the appearance of a fossil vertebral column eroding from rock.
18th century
1760s
1764 The first documented mosasaurid skull is found in the chalk quarries of the St Pietersberg near Maastricht, the Netherlands.Mulder, E.W.A., 2004, "Maastricht Cretaceous finds and Dutch pioneers in vertebrate palaeontology". In: Touret, J.L.R. & Visser, R.P.W. (eds). Dutch pioneers of the earth sciences, pp. 165-176. Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam.
1766 The skull was acquired by lieutenant Jean Baptiste Drouin.
1770s
1772 Around 1772, limestone miners discovered a second skull of a bizarre animal deep underground near Maastricht. The owner of the land containing the mine, canon Theodorus Joannes Godding, displayed it in his country house. Army surgeon John Leonard Hoffman observed the fossil, corresponding with various naturalists about it.Rompen, P. 1995. Mosasaurus hoffmanni: De lotgevallen van een type-exemplaar. Thesis, University of Maastricht
1780s
1784 Drouin sold the first St Pietersberg mosasaur skull to the Teylers Museum at Haarlem where it is still curated today under the catalogue number TM 7424.
1790s
1795 The French revolutionary army took over both Maastricht and Goddin's astonishing fossil. The French misplaced the fossil for a period, before rediscovering it and sending it to Paris for further study.
1798 Adriaan Gilles Camper recognized that the unusual animal resembled a giant monitor lizard, and wrote to Georges Cuvier in Paris stating such.
1799 Camper continued his correspondence with Cuvier and reiterated his opinion that the remains from Maastricht belong to a giant monitor lizard.
19th century
1800s
1804 September 10th
The Lewis and Clark Expedition reportedly found the skeleton of a gigantic snake in an island on the Missouri River in territory now belonging to the state of South Dakota. These remains actually probably belong to a mosasaur, possibly Mosasaurus missouriensis. Some of the bones were sent back to Washington, D.C.
1810s
1818 Mitchell reported the discovery of mosasaur fossils in the Navesink Formation of New Jersey. These were the first North American mosasaur remains to be documented in the scientific literature.
1820s
1820 Samuel von Sömmerring described the new species Lacerta gigantea for fossils discovered in a Bavarian iron mine, mistakenly believing them to be additional remains of the same kind of animal that was discovered in Maastricht. These remains belonged to an animal that was actually more closely related to modern crocodiles and is now known as Geosaurus.
1822 Reverend William Daniel Conybeare formally named the animal from Maastricht Mosasaurus after a river located near the discovery site.
1829 Major Benjamin O'Fallon discovered a mosasaur in what is now South Dakota, near the Great Bend of the Missouri River. He brought it home to St. Louis and later sold it to Prince Maximilian of Wied. Gideon Mantell applied the species epithet "hoffmanni" to the Mosasaurus type species.
1830s
1830 Richard Harlan came into possession of the snout of O'Fallon's mosasaur, but mistook it for an ichthyosaur and described it at Ichthyosaurus missouriensis.
1839 "Ichthyosaurus" missouriensis was "officially" reclassified as Mosasaurus missouriensis.
1840s
1845 August Goldfuss described the new species Mosasaurus maximiliani for the mosasaur, naming it after the Prince.
1850s
1850 Robert Gibbes reported the presence of teeth and vertebrae now recognized as mosasaurian in origin from a limestone deposit in Alabama.
1853 Paul Gervaius creates the family Mosasauridae. Originally included genera are Mosasaurus, Liodon, Onchosaurus (later recognised as a batoid fish), Oplosaurus (later recognised as a sauropod dinosaur), Macrosaurus (a historical wastebasket taxon) and Geosaurus (later recognised as a thalattosuchian).
1860s
1868 Edward Drinker Cope described a variety of new mosasaur taxa from Kansas, including species in the genera Clidastes, Liodon, Mosasaurus, and Platecarpus.
1869 Cope described the species Macrosaurus proriger. This was the first mosasaur to be reported from Kansas. Cope erected the new order Pythonomorpha in which to classify the mosasaurs because of shared traits with modern snakes. He also described the new species Clidastes propython from Alabama. Othniel Charles Marsh described the species Halisaurus platyspondylus.
1870s
1870 Marsh led an expedition into Kansas on behalf of Yale University.
November Marsh's crew discovered the first mosasaur specimen to preserve its hindlimbs in Kansas.
1871 Marsh published a preliminary report about his fossil discoveries in Kansas.