83-446: 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 (the best studied genus by far), Carinodens , Igdamanosaurus , Harranasaurus and Xenodens . Features of
166-419: A M. hoffmannii maxillary tooth measured an average rate of deposition of odontoblasts , the cells responsible for the formation of dentin , at 10.9 micrometers (0.00043 in) per day. This was by observing the von Ebner lines , incremental marks in dentin that form daily. It was approximated that it took the odontoblasts 511 days and dentin 233 days to develop to the extent observed in the tooth. One of
249-409: A 45-foot (14 m) long fish. Richard Ellis speculated in 2003 that this may have been the earliest discovery of the second species M. missouriensis , although competing speculations exist. In 1818, a fossil from Monmouth County, New Jersey became the first North American specimen to be correctly recognized as a Mosasaurus by scientists of the time. The type specimen of M. missouriensis
332-470: A brain around twice the size of that in M. hoffmannii despite being only half the length of the latter. Spaces within the braincase for the occipital lobe and cerebral hemisphere are narrow and shallow, suggesting such brain parts were relatively small. The parietal foramen in Mosasaurus , which is associated with the parietal eye , is the smallest among mosasaurids . The quadrate bone, which connected
415-472: A future formal reassessment. Street & Caldwell (2017) was derived from Street's 2016 doctoral thesis, which contained a phylogenetic study proposing the constraining of Mosasaurus into four species— M. hoffmannii , M. missouriensis , M. lemonnieri , and a proposed new species ' M. glycys ' —with M. conodon and the Pacific taxa recovered as belonging to different genera and M. beaugei view as
498-509: A giant species of Clidastes and named it Clidastes conodon . In 1966, Donald Baird and Gerard R. Case reidentified it as a species of Mosasaurus . Although Cope did not provide the etymology for the specific epithet conodon , it is suggested that it could be a portmanteau meaning "conical tooth", derived from the Ancient Greek κῶνος ( kônos , "cone") and ὀδών ( odṓn , "tooth"), probably in reference to conical surface teeth smooth of
581-553: A globidensin, though most often not) have adaptations to a powerful jaw musculature. The ratio between the length of the supratemporal fenestra and the total length of the skull has previously been used as an improvised measurement for mosasaur bite force, and is quite high in these genera (0.27 in Globidens dakotensis and 0.22 in Prognathodon overtoni and P. saturator ) compared to other mosasaurs like Mosasaurus hoffmannii (with
664-424: A high metabolic rate suggesting it was endothermic ("warm-blooded"), an adaptation in squamates only found in mosasaurs. There is considerable morphological variability across the currently-recognized species in Mosasaurus —from the robustly-built M. hoffmannii to the slender and serpentine M. lemonnieri —but an unclear diagnosis (description of distinguishing features) of the type species M. hoffmannii led to
747-423: A historically problematic classification. As a result, more than fifty species have been attributed to the genus in the past. A redescription of the type specimen in 2017 helped resolve the taxonomy issue and confirmed at least five species to be within the genus. Another five species still nominally classified within Mosasaurus are planned to be reassessed. Fossil evidence suggests Mosasaurus inhabited much of
830-526: A junior synonym of M. hoffmannii . As the type genus of the family Mosasauridae and the subfamily Mosasaurinae, Mosasaurus is a member of the order Squamata (which comprises lizards and snakes ). Relationships between mosasaurs and living squamates remain controversial as scientists still fiercely debate on whether the closest living relatives of mosasaurs are monitor lizards or snakes. Mosasaurus , along with mosasaur genera Eremiasaurus , Plotosaurus , and Moanasaurus traditionally form
913-582: A maximum length of 17.1 meters (56 ft). Using a smaller partial jaw ( NHMM 009002) measuring 90 centimeters (35 in) and "reliably estimated at" 160 centimeters (63 in) when complete, Lingham-Soliar (1995) estimated a larger maximum length of 17.6 meters (58 ft) via the same ratio. No explicit justification for the 1:10 ratio was provided in Russell (1967), and it has been considered to be probably overestimated by Cleary et al. (2018). In 2014, Federico Fanti and colleagues alternatively argued that
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#1733084519823996-444: A multitude of descendant clades containing (in order of most to least basal) Globidens , M. lemonnieri , Goronyosaurus , and Plotosaurus . This result indicated that M. hoffmannii and M. lemonnieri are not in the same genus. However, the study used a method unorthodox to traditional phylogenetic studies on mosasaur species because its focus was on the relationships of entire squamate groups rather than mosasaur classification. As
1079-561: A new tribe due to the clearly distinct features separating Globidens from the rest of the Mosasaurinae and considered Globidens to be a derived descendant of Clidastes . A more recently suggested definition is a branch-based definition diagnosing the Globidensini as the most inclusive clade containing Globidens dakotensis but not Mosasaurus hoffmannii . Both the genera Globidens and Prognathodon (sometimes classified as
1162-676: A proper diagnosis during its initial descriptions, which led to ambiguity in how the genus is defined. This led Mosasaurus to become a wastebasket taxon containing as many as fifty different species. A 2017 study by Hallie Street and Michael Caldwell performed the first proper diagnosis and description of the M. hoffmannii holotype, which allowed a major taxonomic cleanup confirming five species as likely valid— M. hoffmannii , M. missouriensis , M. conodon , M. lemonnieri , and M. beaugei . The study also held four additional species from Pacific deposits— M. mokoroa , M. hobetsuensis , M. flemingi , and M. prismaticus —to be possibly valid, pending
1245-452: A ratio of 0.19). Globidensini Mosasaurinae 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 lineage first appears in the Turonian and thrived until
1328-512: A result, some paleontologists caution that lower-order classification results from Conrad's 2008 study such as the specific placement of Mosasaurus may contain technical problems, making them inaccurate. The following cladogram on the left (Topology A) is modified from a maximum clade credibility tree inferred by a Bayesian analysis in the most recent major phylogenetic analysis of the Mosasaurinae subfamily by Madzia & Cau (2017), which
1411-454: A sister relationship with another group which included Globidens and Prognathodon , and M. maximus as a sister species to Plotosaurus . The latter rendered Mosasaurus paraphyletic (an unnatural grouping), but Bell (1997) nevertheless recognized Plotosaurus as a distinct genus. Bell's study served as a precedent for later studies that mostly left the systematics of Mosasaurus unchanged, although some later studies have recovered
1494-427: A skull approaching 1 meter (3.3 ft) in length. Based on personal observations of various unpublished fossils from Morocco, Nathalie Bardet et al. (2015) estimated that M. beaugei grew to a total length of 8–10 meters (26–33 ft), their skulls typically measuring around 1 meter (3.3 ft) in length. With a referred skull measuring 97.7 centimeters (38.5 in) in length, M. conodon has been regarded as
1577-488: A skull recovered by Alfred Lemonnier from a phosphate quarry in Belgium, a holotype since cataloged as IRSNB R28. Dollo names the species in his honor. Further mining of the quarry in subsequent years uncovered many additional well-preserved fossils, including multiple partial skeletons which collectively represented nearly the entire skeleton of the species. They were described by Dollo in later papers. Despite being one of
1660-399: A small to medium-sized representative of the genus. The skull of Mosasaurus is conical and tapers off to a short snout which extends a little beyond the frontmost teeth. In M. hoffmannii , this snout is blunt, while in M. lemonnieri it is pointed. Above the gum line in both jaws, a single row of small pits known as foramina are lined parallel to the jawline; they are used to hold
1743-443: A streamlined body, an elongated tail ending with a downturn supporting a two-lobed fin, and two pairs of flippers. While in the past derived mosasaurs were depicted as akin to giant flippered sea snakes , it is now understood that they were more similar in build to other large marine vertebrates such as ichthyosaurs, marine crocodylomorphs , and archaeocete whales through convergent evolution . The type species, M. hoffmannii ,
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#17330845198231826-595: A tribe within the Mosasaurinae variously called Mosasaurini or Plotosaurini. One of the earliest relevant attempts at an evolutionary study of Mosasaurus was done by Russell in 1967. He proposed that Mosasaurus evolved from a Clidastes -like mosasaur, and diverged into two lineages, one giving rise to M. conodon and another siring a chronospecies sequence which contained in order of succession M. ivoensis , M. missouriensis , and M. maximus-hoffmanni . However, Russell used an early method of phylogenetics and did not use cladistics. In 1997, Bell published
1909-491: A water-going monitor lizard. It was given a boxy head, nostrils at the side of the skull, large volumes of soft tissue around the eyes, lips reminiscent of monitor lizards, scales consistent with those in large monitors like the Komodo dragon , and a flipper. The model was deliberately sculpted incomplete, which Mark Witton believed was likely to save time and money. Many elements of the sculpture can be considered inaccurate, even for
1992-574: Is a life-size concrete sculpture created by Benjamin Waterhouse Hawkins between 1852 and 1854 as part of the collection of sculptures of prehistoric animals on display at the Crystal Palace Park in London . The restoration was primarily informed by Richard Owen 's interpretation of the M. hoffmannii holotype and the anatomy of monitor lizards, so Hawkins depicted the animal as essentially
2075-434: Is around 1.5 times longer than the femur . The femur itself is about twice as long as it is wide and ends at the distal side in a pair of distinct articular facets (of which one connects to the ilium and the other to the paddle bones) that meet at an angle of approximately 120°. Five sets of metacarpals and phalanges (finger bones) were encased in and supported the paddles, with the fifth set being shorter and offset from
2158-485: Is estimated to measure up to 12 meters (39 ft) in maximum length, making it one of the largest mosasaurs. The skull of Mosasaurus had robust jaws and strong muscles capable of powerful bites using dozens of large teeth adapted for cutting prey . Its four limbs were shaped into paddles to steer the animal underwater. Its tail was long and ended in a downward bend and a paddle-like fluke. Mosasaurus possessed excellent vision to compensate for its poor sense of smell, and
2241-495: Is one of the largest marine reptiles known, though knowledge of its skeleton remains incomplete as it is mainly known from skulls. Russell (1967) wrote that the length of the jaw equalled one tenth of the body length in the species. Based on this ratio, Grigoriev (2014) used the largest lower jaw attributed to M. hoffmannii (CCMGE 10/2469, also known as the Penza specimen; measuring 171 centimeters (67 in) in length) to estimate
2324-573: The Globidensini , evolved specialized crushing teeth, adapting to a diet of ammonites and/or marine turtles . Though represented by relatively small forms throughout the Turonian and Santonian , such as Clidastes , the lineage diversified during the Campanian and had by the Maastrichtian grown into the most diverse and species-rich mosasaur subfamily. The etymology of the group derives from
2407-485: The K-Pg mass extinction at the end of the Maastrichtian . They ranged in size from some of the smallest known mosasaurs ( Carinodens , 3–3.5 meters), to medium-sized taxa ( Clidastes , 6+ meters), to the largest of the mosasaurs ( Mosasaurus hoffmannii ) potentially reaching about 13 m in length. Many genera of mosasaurines were either piscivorous or generalists, preying on fish and other marine reptiles, but one lineage,
2490-469: The Mesozoic ever since the extinction of the placodonts and the durophagous ichthyosaur Grippia . The rarity of the Globidensini in the fossil record remains a mystery, perhaps it is due to habitat preference (deep water), some other form of taphonomic bias or due to the durophagous lifestyle not allowing the establishment of large populations in the first place. In Angola, the disappearance coincides with
2573-513: The Meuse River ") is the type genus (defining example) 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
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2656-559: The Pembina Gorge State Recreation Area in North Dakota was found to have an unusual count of sixteen pterygoid teeth, far greater than in known species. The dentition was thecodont (tooth roots deeply cemented within the jaw bone). Teeth were constantly shed through a process where the replacement tooth developed within the root of the original tooth and then pushed it out of the jaw. Chemical studies conducted on
2739-1336: The Prognathodontini ( Prognathodon and its closest relatives, such as Plesiotylosaurus ), is also used on occasion. "Clidastini" or the adjective "clidastine" is also used sometimes, but generally refers to an adaptive grade close to and containing the genus Clidastes , rather than an actual clade. Cladogram of the Mosasaurinae modified from Longrich et al. , 2022: Kourisodon Clidastes Globidens simplex Globidens schumani Globidens phosphaticus Prognathodon rapax (= Ancylocentrum hungerfordi ) Globidens alambamensis Globidens dakotensis Gnathomortis Prognathodon overtoni Prognathodon saturator Thalassotitan atrox Prognathodon currii Prognathodon giganteus Prognathodon lutugini Prognathodon solvayi Moanasaurus Mosasaurus mokoroa Mosasaurus conodon Plesiotylosaurus Plotosaurus Mosasaurus missouriensis Mosasaurus lemonnieri Mosasaurus hoffmannii Mosasaurus beaugei Mosasaurus maximus Liodon Mosasaurus sp. (MGGC 21876) "Magahouanga mosasaurine" Carinodens Xenodens Mosasaurus hoffmannii Mosasaurus ( / ˌ m oʊ z ə ˈ s ɔːr ə s / ; "lizard of
2822-514: The phylogeny of the Mosasauroidea, Bell (pp. 293–332) retained the Mosasaurinae as a clade , though he reassigned Russell's tribe Prognathodontini to the Mosasaurinae and recognized a new tribe of mosasaurines, the Globidensini . The subfamily is generally recognised as containing two subdivisions, the tribes Globidensini ( Globidens and its closest relatives) and Mosasaurini ( Mosasaurus and its closest relatives). A third tribe,
2905-743: The Atlantic Ocean and the adjacent seaways. Mosasaurus fossils have been found in North and South America, Europe, Africa, Western Asia, and Antarctica. This distribution encompassed a wide range of oceanic climates including tropical, subtropical, temperate, and subpolar. Mosasaurus was a common large predator in these oceans and was positioned at the top of the food chain . Paleontologists believe its diet would have included virtually any animal; it likely preyed on bony fish, sharks, cephalopods , birds, and other marine reptiles including sea turtles and other mosasaurs. It likely preferred to hunt in open water near
2988-457: The Dutch city of Maastricht in the late 18th century, and were initially thought to be crocodiles or whales. One skull discovered around 1780 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
3071-562: The Meuse", in reference to the river where the holotype specimen was discovered nearby. In 1829, Gideon Mantell added the specific epithet hoffmannii , in honor to Hoffmann. Later, the second skull is designated as the new species' holotype (defining example). In 1804, the Lewis and Clark Expedition discovered a now-lost fossil skeleton alongside the Missouri River , which was identified as
3154-431: The bar is robust and does not constrict. The external nares ( nostril openings ) are moderately sized and measure around 21–24% of the skull's length in M. hoffmannii . They are placed further toward the back of the skull than in nearly all other mosasaurs (exceeded only by Goronyosaurus ), and begin above the fourth or fifth maxillary teeth. As a result, the rear portions of the maxilla (the main tooth-bearing bone of
3237-464: The best anatomically represented species, M. lemonnieri was largely ignored in scientific literature. Theagarten Lingham-Soliar suggested two reasons for this neglect. First, M. lemonnieri fossils are endemic to Belgium and the Netherlands, which despite the famous discovery of the M. hoffmannii holotype attracted little attention from mosasaur paleontologists. Second, the species was overshadowed by
3320-406: The bones is virtually identical with in modern whales, which indicates Mosasaurus possessed a high range of aquatic adaptation and neutral buoyancy as seen in cetaceans. The tail structure of Mosasaurus is similar to relatives like Prognathodon , in which soft tissue evidence for a two-lobed tail is known. The tail vertebrae gradually shorten around the center of the tail and lengthen behind
3403-399: The center, suggesting rigidness around the tail center and excellent flexibility behind it. Like most advanced mosasaurs, the tail bends slightly downwards as it approached the center, but this bend is offset from the dorsal plane at a small degree. Mosasaurus also has large haemal arches located at the bottom of each caudal vertebra which bend near the middle of the tail, which contrasts with
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3486-433: The dentary is slightly curved upwards; this is also the case with the largest specimens of M. lemonnieri , although more typical skulls of the species have a near-perfectly straight jawline. The premaxillary bar, the long portion of the premaxillary bone extending behind the premaxillary teeth, is narrow and constricts near the middle in M. hoffmannii and M. lemonnieri like in typical mosasaurs. In M. missouriensis ,
3569-524: The early and mid-1800s initially imagined Mosasaurus as an amphibious marine reptile with webbed feet and limbs for walking . This was based on fossils like the M. missouriensis holotype, which indicated an elastic vertebral column that Goldfuss in 1845 saw as evidence of an ability to walk and interpretations of some phalanges as claws. In 1854, Hermann Schlegel proved how Mosasaurus actually had fully aquatic flippers. He clarified that earlier interpretations of claws were erroneous and demonstrated how
3652-899: The extinction of Inoceramus shells. The robust and globular teeth have on occasion been compared to the genera Prognathodon and Plesiotylosaurus , both of which sometimes are included within the tribe. Said genera are probably not as closely connected to Globidens as such an inclusion would suggest. The etymology of the tribe derives from the genus Globidens ( Latin Globus = "globe" + Latin dens = "teeth"). Overall, globidensins were medium-sized mosasaurs, with Globidens itself reaching about 6 meters in length. The teeth of Globidens , Carinodens and Igdamanosaurus differ from those of all other mosasaurs in being very robust and globular. Most mosasaur genera have sharp teeth adapted to grab soft and slippery prey like fish and cephalopods . Though some clearly were capable of crushing through
3735-420: The first cladistical study of North American mosasaurs. Incorporating the species M. missouriensis , M. conodon , M. maximus , and an indeterminate specimen ( UNSM 77040), some of his findings agreed with Russell (1967), such as Mosasaurus descending from an ancestral group containing Clidastes and M. conodon being the most basal of the genus. Contrary to Russell (1967), Bell also recovered Mosasaurus in
3818-566: The fossil into cultural fame, but historians agree that the narrative was exaggerated. After its seizure, the second skull was sent to the National Museum of Natural History, France in 1795 and later cataloged as MNHN AC 9648. By 1800, Camper's son Adriaan Gilles Camper concluded that the fossil, which by then was nicknamed the "great animal of Maastricht", belonged to a marine reptile sharing affinities to monitor lizards , but otherwise unlike any modern animal. Georges Cuvier confirmed
3901-548: The fossil snout became lost. The von Meyer's suggestion was confirmed in 2004, when the snout was found in the collections of the MNHN under the catalog number MNHN 958. The third species was described in 1881 by Edward Drinker Cope from a fragmentary fossil skeleton having been discovered in New Jersey , now cataloged as AMNH 1380. In his description, the Cope thought that it represented
3984-1011: The genus Mosasaurus ( Latin Mosa = " Meuse river " + Greek sauros = "lizard"). Russell (1967, pp. 123–124) defined the Mosasaurinae as differing from all other mosasaurs as follows: "Small rostrum present or absent anterior to premaxillary teeth. Fourteen or more teeth present in dentary and maxilla . Cranial nerves X, XI, and XII leave lateral wall of opisthotic through two foramina. No canal or groove in floor of basioccipital or basisphenoid for basilar artery. Suprastapedial process of quadrate distally expanded. Dorsal edge of surangular thin lamina of bone rising anteriorly to posterior surface of coronoid...At least 31, usually 42–45 presacral vertebrae present. Length of presacral series exceeds that of postsacral, neural spines of posterior caudal vertebrae elongated to form distinct fin. Appendicular elements with smoothly finished articular surfaces, tarsus and carpus well ossified." In his 1997 revision of
4067-875: The jaws ( homodont ) except for the smaller pterygoid teeth. The number of teeth in the maxillae, pterygoids, and dentaries vary between species and sometimes even individuals— M. hoffmannii had fourteen to sixteen maxillary teeth, fourteen to fifteen dentary teeth, and eight pterygoid teeth; M. missouriensis had fourteen to fifteen maxillary teeth, fourteen to fifteen dentary teeth, and eight to nine pterygoid teeth; M. conodon had fourteen to fifteen maxillary teeth, sixteen to seventeen dentary teeth, and eight pterygoid teeth; M. lemonnieri had fifteen maxillary teeth, fourteen to seventeen dentary teeth, and eleven to twelve pterygoid teeth; and M. beaugei had twelve to thirteen maxillary teeth, fourteen to sixteen dentary teeth, and six or more pterygoid teeth. One indeterminate specimen of Mosasaurus similar to M. conodon from
4150-432: The labial side (the side facing outwards) and no prisms on the lingual side (the side facing the tongue), M. missouriensis had four to six labial prisms and eight lingual prisms, M. lemonnieri had eight to ten labial prisms, and M. beaugei had three to five labial prisms and eight to nine lingual prisms. Like all mosasaurs, Mosasaurus had four types of teeth, classified based on the jaw bones they were located on. On
4233-500: The lack of a clear holotype diagnosis, which may have been behind the genus's paraphyletic status. Third, there was still a lack of comparative studies of the skeletal anatomy of large mosasaurines at the time. These problems were addressed in Street's 2016 thesis in an updated phylogenetic analysis. Conrad uniquely used only M. hoffmannii and M. lemonnieri in his 2008 phylogenetic analysis, which recovered M. hoffmannii as basal to
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#17330845198234316-414: The lower jaw to the rest of the skull and formed the jaw joint, is tall and somewhat rectangular in shape, differing from the rounder quadrates found in typical mosasaurs. The quadrate also housed the hearing structures , with the eardrum residing within a round and concave depression in the outer surface called the tympanic ala. The trachea likely stretched from the esophagus to below the back end of
4399-1016: The lower jaw's coronoid process , where it split into smaller pairs of bronchi which extended parallel to each other. The features of teeth in Mosasaurus vary across species, but unifying characteristics include a design specialized for cutting prey, highly prismatic surfaces (enamel circumference shaped by flat sides called prisms), and two opposite cutting edges. Mosasaurus teeth are large and robust except for those in M. conodon and M. lemonnieri , which instead have more slender teeth. The cutting edges of Mosasaurus differ by species. The cutting edges in M. hoffmannii and M. missouriensis are finely serrated, while in M. conodon and M. lemonnieri serrations do not exist. The cutting edges of M. beaugei are neither serrated nor smooth, but instead possess minute wrinkles known as crenulations. The number of prisms in Mosasaurus teeth can slightly vary between tooth types and general patterns differ between species — M. hoffmannii had two to three prisms on
4482-567: 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 . Towards the end of the Cretaceous, a series of adaptations allowed the highly specialized mosasaurs within the Globidensini, characterized by knob-like teeth, to successfully reclaim the niche of the durophagous lifestyle. This niche had been unoccupied for most of
4565-453: The more famous and history-rich type species . M. lemonnieri is a controversial taxon, and there is debate on whether it is a distinct species or not. In 1967, Dale Russell argued that M. lemonnieri and M. conodon are the same species and designated the former as a junior synonym per the principle of priority . In a 2000 study, Lingham-Soliar refuted this based on a comprehensive study of existing M. lemonnieri specimens, which
4648-885: The most complete Mosasaurus skeletons in terms of vertebral representation ( Mosasaurus sp.; SDSM 452) has seven cervical (neck) vertebrae , thirty-eight dorsal vertebrae (which includes thoracic and lumbar vertebrae ) in the back, and eight pygal vertebrae (front tail vertebrae lacking haemal arches ) followed by sixty-eight caudal vertebrae in the tail. All species of Mosasaurus have seven cervical vertebrae, but other vertebral counts vary among them. Various partial skeletons of M. conodon , M. hoffmannii , and M. missouriensis suggest M. conodon likely had up to thirty-six dorsal vertebrae and nine pygal vertebrae; M. hoffmannii had likely up to thirty-two dorsal vertebrae and ten pygal vertebrae; and M. missouriensis around thirty-three dorsal vertebrae, eleven pygal vertebrae, and at least seventy-nine caudal vertebrae. M. lemmonieri had
4731-489: The most vertebrae in the genus, with up to around forty dorsal vertebrae, twenty-two pygal vertebrae, and ninety caudal vertebrae. Compared to other mosasaurs, the rib cage of Mosasaurus is unusually deep and forms an almost perfect semicircle, giving it a barrel-shaped chest. Rather than being fused together, extensive cartilage likely connected the ribs with the sternum , which would have facilitated breathing movements and compression when in deeper waters. The texture of
4814-480: The observations of Camper Jr. in a more in-depth study which was published in 1808. The skull became part of Cuvier's first speculations about the conception of extinction , which later led to his theory of catastrophism , a precursor to the theory of evolution . At the time, it was not believed that a species could go extinct, and fossils of animals were often interpreted as some form of an extant species. Cuvier's idea that there existed an animal unlike any today
4897-473: The phalanges show no indication of muscle or tendon attachment, which would make walking impossible. They are also broad, flat, and form a paddle. Schlegel's hypothesis was largely ignored by contemporary scientists but became widely accepted by the 1870s when Othniel Charles Marsh and Cope uncovered more complete mosasaur remains in North America. One of the earliest depictions of Mosasaurus in paleoart
4980-445: The possession of prince Maximilian of Weid-Neuwied between 1832 and 1834. The fossil skull, now cataloged as RFWUIP 1327, was delivered to Georg August Goldfuss in Bonn for research, who published a study in 1845. The same year, Christian Erich Hermann von Meyer suspected that the skull and Harlan's snout were part of the same individual. This could not be confirmed at the time because
5063-581: The prominent biologist Petrus Camper , and the skull gained international attention after Camper published a study identifying it as a whale. This caught the attention of French revolutionaries , who looted the fossil following the capture of Maastricht during the French Revolutionary Wars in 1794. In a 1799 narrative of this event by Barthélemy Faujas de Saint-Fond , the skull was allegedly retrieved by twelve grenadiers in exchange for an offer of 600 bottles of wine. This story helped elevate
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#17330845198235146-440: The reduction of haemal arches in other marine reptiles such as ichthyosaurs . These and other features support a large and powerful paddle-like fluke in Mosasaurus . The forelimbs of Mosasaurus are wide and robust. The scapula and humerus are fan-shaped and wider than tall. The radius and ulna are short, but the former is taller and larger than the latter. The ilium is rod-like and slender; in M. missouriensis , it
5229-507: The rest. The overall structure of the paddle is compressed, similar to in Plotosaurus , and was well-suited for faster swimming. In the hindlimbs, the paddle is supported by four sets of digits. Interactive skeletal reconstruction of M. hoffmannii (hover over or click on each skeletal component to identify the structure) Because nomenclatural rules were not well-defined at the time, 19th century scientists did not give Mosasaurus
5312-410: The same ecosystems through niche partitioning . There were still conflicts among them, as an instance of Tylosaurus attacking a Mosasaurus has been documented. Several fossils document deliberate attacks on Mosasaurus individuals by members of the same species. In fighting likely took place in the form of snout grappling, as seen in modern crocodiles. The first Mosasaurus fossil known to science
5395-490: The same ratio, Gayford et al. (2024) calculated the total length for the Penza specimen to be 12 meters (39 ft). Isolated bones suggest some M. hoffmannii may have exceeded the lengths of the Penza specimen. One such bone is a quadrate (NHMM 003892) which is 150% larger than the average size, which Everhart and colleagues in 2016 reported can be extrapolated to scale an individual around 18 meters (59 ft) in length. It
5478-430: The shells of armored prey, none were as specialized as Globidens and its kin, which combined robust and powerful skulls with semispherical teeth capable of crushing through the shells of animals like ammonites , bivalves and small turtles . Russell (1967) did not offer a proper diagnosis for the tribe when he named it, due to how poorly known the osteology of Globidens was at the time, but nevertheless erected
5561-401: The sister group to Mosasaurus and Plotosaurus to instead be Eremiasaurus or Plesiotylosaurus depending on the method of data interpretation used, with at least one study also recovering M. missouriensis to be the most basal species of the genus instead of M. conodon . In 2014, Konishi and colleagues expressed a number of concerns with the reliance on Bell's study. First, the genus
5644-447: The skull constituted approximately one-eleventh of the whole body. Polcyn et al. (2014) estimated that M. missouriensis may have measured up to 8–9 meters (26–30 ft) in length. Street (2016) noted that large M. missouriensis individuals typically had skulls exceeding lengths of 1 meter (3.3 ft). A particular near-complete skeleton of M. missouriensis is reportedly measured at 6.5 meters (21 ft) in total length with
5727-459: The species. The fourth species M. lemonnieri was first detected by Camper Jr. based on fossils from his father's collections, which he discussed with Cuvier during their 1799 correspondence. Although Cuvier rejected the idea of another Mosasaurus species, Camper Jr. nevertheless published his findings in 1812 without establishing a scientific name. This species was re-introduced to science and formally described in 1889 by Louis Dollo based on
5810-541: The surface. From an ecological standpoint, Mosasaurus probably had a profound impact on the structuring of marine ecosystems; its arrival in some locations such as the Western Interior Seaway in North America coincides with a complete turnover of faunal assemblages and diversity. Mosasaurus faced competition with other large predatory mosasaurs such as Prognathodon and Tylosaurus —which were known to feed on similar prey—though they were able to coexist in
5893-459: The terminal branches of jaw nerves. The foramina along the snout form a pattern similar to the foramina in Clidastes skulls. The upper jaws in most species are robustly built, broad, and deep except in M. conodon , where they are slender. The disparity is also reflected in the dentary , the lower jawbone, although all species share a long and straight dentary. In M. hoffmannii , the top margin of
5976-550: The time and helped support the then-developing ideas of extinction . Cuvier did not designate a scientific name for the animal; 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 . The largest species, M. hoffmannii ,
6059-399: The time. It did not take into account Golduss' 1845 study of M. missouriensis which instead called for a narrower skull, nostrils at the top of the skull, and amphibious terrestrial limbs (the latter being incorrect in modern standards ). Mosasaurus was a type of derived mosasaur, or a latecoming member with advanced evolutionary traits such as a fully aquatic lifestyle. As such, it had
6142-437: The total length of M. hoffmannii was more likely closer to seven times the length of the skull, which was based on a near-complete skeleton of the related species Prognathodon overtoni . The study estimated that an M. hoffmannii individual with a skull measuring more than 145 cm (57 in) would have been up to or more than 11 meters (36 ft) in length and weighed 10 metric tons (11 short tons) in body mass. Using
6225-442: The upper jaw) lack the dorsal concavity that would fit the nostrils in typical mosasaurs. The palate , which consists of the pterygoid bones, palatine bone , and nearby processes of other bones, is tightly packed to provide greater cranial stability. The neurocranium housed a brain which was narrow and relatively small compared to other mosasaurs. For example, the braincase of the mosasaur Plioplatecarpus marshi provided for
6308-483: The upper jaw, there were three types: the premaxillary teeth, maxillary teeth, and pterygoid teeth. On the lower jaw, only one type, the dentary teeth, were present. In each jaw row, from front to back, Mosasaurus had: two premaxillary teeth, twelve to sixteen maxillary teeth, and eight to sixteen pterygoid teeth on the upper jaw and fourteen to seventeen dentary teeth on the lower jaw. The teeth were largely consistent in size and shape with only minor differences throughout
6391-403: Was corroborated by a study on the M. conodon skull by Takehito Ikejiri and Spencer G. Lucas in 2014. In 2004, Eric Mulder, Dirk Cornelissen, and Louis Verding suggested M. lemonnieri could be a juvenile form of M. hoffmannii based on the argument that significant differences could be explained by age-based variation. However, the need for more research to confirm any hypotheses of synonymy
6474-522: Was discovered in 1764 in a chalk quarry near Maastricht in the Netherlands in the form of a skull, which was initially identified as a whale . This specimen, cataloged as TM 7424, is now on display at the Teylers Museum in Haarlem . Later around 1780, the quarry produced a second skull that caught the attention of the physician Johann Leonard Hoffmann , who thought it was a crocodile . He contacted
6557-696: Was expressed. The fifth species M. beaugei was described by Camille Arambourg in 1952 from isolated teeth originating from phosphate deposits in the Oulad Abdoun Basin and the Ganntour Basin in Morocco, the holotype tooth being cataloged as MNHN PMC 7. The species is named in honor of Alfred Beaugé, director at the time of the OCP Group , who invited Arambourg to participate in the research project and helped him to provide local fossils. Scientists during
6640-478: Was first described in 1834 by Richard Harlan based on a snout fragment found along the river's Big Bend , in South Dakota . In reference to its discovery made in the river, he coined the specific epithet and initially identified it as a species of Ichthyosaurus but later as an amphibian named Batrachiosaurus . The rest of the skull had been discovered earlier by a fur-trapper, and it eventually came under
6723-444: Was not stated whether they applied Russell's 1967 ratio, although Gayford et al. (2024) suggested it was likely. M. missouriensis and M. lemonnieri are smaller than M. hoffmannii but are known from more complete fossils. Based on measurements of various Belgian skeletons, Dollo estimated M. lemonnieri grew to around 7 to 10 meters (23 to 33 ft) in length. He also measured the dimensions of IRSNB 3119 and recorded that
6806-493: Was revolutionary at the time, and in 1812 he proclaimed, "Above all, the precise determination of the famous animal from Maastricht seems to us as important for the theory of zoological laws, as for the history of the globe." In a 1822 work by James Parkinson , William Daniel Conybeare coined the genus Mosasaurus from the Latin Mosa " Meuse " and the Ancient Greek σαῦρος ( saûros , "lizard"), all literally meaning "lizard of
6889-402: Was severely underrepresented by incorporating only the three North American species M. hoffmannii/M. maximus , M. missouriensis , and M. conodon ; by doing so, others like M. lemonnieri , which is one of the most completely known species in the genus, were neglected, which affected phylogenetic results. Second, the studies relied on an unclean and shaky taxonomy of the Mosasaurus genus due to
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