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{{Short description|Extinct genus of lizards}}
{{Automatic taxobox
|
| authority = Gilmore, 1912
| fossil_range =
| image = Globidens NMNH.jpg
| image_caption = Reconstructed skull of ''G. phosphaticus'', [[National Museum of Natural History]]
| subdivision_ranks = Species
| subdivision = * ''G. alabamaensis'' <small>([[Type (biology)|Type]]) <br />Gilmore, 1912</small>
* ''G. dakotensis'' <small>Russell, 1975</small>
* ''G. hisaensis'' <small>Kaddumi, 2009</small>
* ''G. phosphaticus'' <small>Bardet and Pereda-Suberbiola, 2005</small>
* ''G. schurmanni'' <small>Martin, 2007</small>
* ''G. simplex'' <small>LeBlanc ''et al.'', 2019</small>
}}
'''''Globidens''''' ("Globe tooth") is an [[extinct]] [[genus]] of [[mosasaur]]id oceanic [[lizard]] classified as part of the [[Globidensini]] tribe in the [[Mosasaurinae]] subfamily. ''Globidens'' belongs to the family [[Mosasauridae]], which consists of several genera of predatory marine lizards of various sizes that were prevalent during the [[Late Cretaceous]]. Specimens of ''Globidens'' have been discovered in [[Angola]], [[Brazil]], [[Colombia]], [[Morocco]], [[Syria]] and the [[United States]].<ref name="The North African Mosasaur Globiden">{{cite journal |last1=Polcyn |first1=Michael J. |last2=Jacobs |first2=Louis L. |last3=Schulp |first3=Anne S. |last4=Mateus |first4=Octávio |title=The North African Mosasaur Globidens phosphaticus from the Maastrichtian of Angola |journal=Historical Biology |volume=22 |issue=1–3 |pages=175–185 |doi=10.1080/08912961003754978 |date=1 March 2010}}</ref> Among mosasaurs, ''Globidens'' is probably most well known for the highly rounded, globe-like teeth that give it its name.
''Globidens alabamaensis'' was the first species of ''Globidens'' described, in a publication by [[Charles W. Gilmore]] (1912). It is used as the [[Type (biology)|type]] specimen for ''Globidens''.
==Description==
[[Image:GlobidensDB2.jpg|thumb|left|Life restoration of ''G. alabamaensis'']]
''Globidens'' was a relatively medium-sized mosasaur, measuring about {{convert|5|-|6|m|ft}} long.<ref>{{cite journal|first1=S.L.A.|last1=Cooper|first2=K.J.|last2=Marson|first3=R.E.|last3=Smith|first4=D.|last4=Martill|year=2022|title=Contrasting preservation in pycnodont fishes reveals first record of regurgitalites from the Upper Cretaceous (Maastrichtian) Moroccan phosphate deposits|journal=Cretaceous Research|volume=131|issue=4|at=105111|doi=10.1016/j.cretres.2021.105111}}</ref> It was similar in appearance to other mosasaurs, with its streamlined body, [[flipper (anatomy)|flipper]]s, a laterally flattened [[tail]], and powerful [[jaw]]s. The [[teeth]] of ''Globidens'' differed from those of other mosasaurs in being rounded or “globular”, giving rise to its generic name. Most mosasaurs had sharp teeth evolved to grab soft, slippery prey like [[fish]], [[squid]], plesiosaurs, and other mosasaurs. In some later mosasaur species, their teeth were modified to rend flesh as well. While many other mosasaurs were capable of crushing the shells of ammonites or turtles, none were as specialized for dealing with armored prey as ''Globidens''. ''Globidens'' had semispherical teeth with rounded points suited for crushing tough, armored prey, including [[turtle]]s, [[ammonite]]s, [[nautilus|nautili]], and [[bivalve]]s. Like its larger relative, ''[[Mosasaurus]]'', ''Globidens'' had a robustly built skull with tightly-articulating jaws and a strong bite that played a large role in the animal’s ability to penetrate the armor of its shelled prey.
Gilmore's initial assessment of ''Globidens'', based on an incomplete specimen of ''G. alabamaensis'', made note of characteristics observable in parts of the skull, the teeth, and one of the [[cervical vertebrae]]. He made note of a long snout with a large [[maxilla]], a large, sturdy [[frontal bone]], and the characteristic globular teeth with finely wrinkled enamel. Gilmore concluded that the skull characters were similar to ''[[Platecarpus]]'' or, more closely, to ''Brachysaurus'' (which is currently ''[[Prognathodon]]'').
[[File:Globidens dakotensis skull.jpg|thumb|left|Reconstructed skull of ''G. dakotensis'']]
Studies since Gilmore's assessment establish more specific and more complete lists of diagnostic features. Gilmore correctly inferred that ''Globidens'' had a stout, powerfully built skull. In addition, a few of its notable skull characteristics include a small parietal foramen located entirely within the parietal, tuberosities present on the [[jugal]], a longitudinal crest present on the dorsal surface of the frontal, and a [[premaxilla]] with a rostrum anterior to the premaxillary teeth.<ref name="Russel - New sp. of Globidens from SD" /> The rounded teeth with finely wrinkled enamel seen in ''Globidens'' are characteristic of Globidensini. However, the degree of rounding on individual teeth may be indicative of genus or even species. Marginal teeth in ''Globidens'' become most subspherical toward the center of the jaws. Additionally, ''Globidens'' had thirteen maxillary teeth and either lacked or showed only rudimentary [[pterygoid bone|pterygoid]] teeth on the roof of its mouth.<ref name="Russel - New sp. of Globidens from SD" />
==History of discovery==
[[File:Globidens FMNH.jpg|left|thumb|242x242px|Skull of ''G. dakotensis'' (bottom view), [[Field Museum of Natural History]]]]
''Globidens'' was first described in 1912 by [[Charles W. Gilmore]]. Using an incomplete specimen made of only of a partial skull with several teeth, a single cervical vertebra, and numerous fragments, Gilmore identified ''Globidens'' as a new genus and named his type specimen ''Globidens alabamaensis''. The genus name was based on the globular structure of the specimen's teeth and the species name on the ___location in which it was discovered: [[Alabama]]. However, it may be noted that the original ___location from which the specimen was taken is not precisely known, as Gilmore was examining a specimen that had been collected earlier.<ref name="Gilmore1912">{{cite journal |last=Gilmore |first=Charles W. |year=1912 |title=A new mosasauroid reptile from the Cretaceous of Alabama |url=https://repository.si.edu/bitstream/handle/10088/14313/1/USNMP-41_1870_1912.pdf |journal=Proceedings of the United States National Museum |volume=41 |issue=1870 |pages=479–484}}</ref>
Since Gilmore's identification of ''Globidens'', several other species have been identified, including ''G. dakotensis'' (Russell 1975), which is sometimes used as a secondary type specimen alongside ''G. alabamaensis''. Some specimens previously thought to be new species of ''Globidens'' have since been reassigned to other taxa, such as ''Prognathodon'', or placed in a new taxa, such as ''G. aegypticus'', which is now a type specimen for ''Igdamanosaurus''.<ref name="Lingham-Soliar - Igdamanosaurus" />
===Species===
[[File:Left maxilla of holotype of Globidens, USNM 6527.jpg|upright|thumb|Holotype maxilla (USNM 6527.jpg) of ''G. alabamaensis'']]
*''Globidens alabamaensis'' Gilmore, 1912 - (''Generic type'') The height of the tooth crown is less than the greatest tooth crown diameter behind the seventh maxillary tooth. The crown length is greater than the crown width in front of the tenth maxillary tooth. The maxilla is long and the frontal is narrow. The frontal bone slightly enters the orbits dorsally.<ref name="Russel - New sp. of Globidens from SD" />
*''G. dakotaensis'' Russell, 1975 - The height of the tooth crown is less than the greatest tooth crown diameter behind the fourth maxillary tooth. The crown length is greater than the crown width in front of the tenth maxillary tooth. The maxilla is long and the frontal is broad. The frontal bone does not enter the orbits dorsally.<ref name="Russel - New sp. of Globidens from SD" />
*''G. phosphaticus'' Bardet et al. 2005<ref name="Bardet - Durophages" /> from Morocco and Angola.<ref name="The North African Mosasaur Globiden" />
*''G. schurmanni'' Martin, 2007.
*''G. hisaensis'' Kaddumi, 2009 from central Jordan.<ref>{{Cite book |last=Kaddumi |first=Hani F. |title=Fossils of the Harrana Fauna and the Adjacent Areas |publisher=Eternal River Museum of Natural History |year=2009 |___location=Amman |pages= |chapter=A new species of ''Globidens'' (Squamata: Mosasauridae) from the late Campanian-early Maastrichtian of Jordan |oclc=709582892 |chapter-url=https://www.academia.edu/19803459/A_new_species_of_Globidens_Squamata_Mosasauridae_from_the_late_Campanian_early_Maastrichtian_of_Jordan}}</ref>
*''G. simplex'' LeBlanc ''et al.'' 2019 from Morocco. A complete mandible and partial skull was recovered, showing large jaw adductor musculature attachment points indicative of hard shelled prey. A shortened dentary with respect to the Posterior Mandibular Unit relative to other globidensine mosasaurs supports this as well. Postcranial remains were also recovered and histological analysis of one rib showed increased bone compactness reminiscent of conditions seen in early stages of marine tetrapod evolution, suggesting increased ability to stay submerged for long periods along the sea floor.<ref>{{Cite journal|last=LeBlanc|first=Aaron|last2=Mohr|first2=Sydney|last3=Caldwell|first3=Michael|date=2019|title=Insights into the anatomy and functional morphology of durophagous mosasaurines (Squamata: Mosasauridae) from a new species of Globidens from Morocco|journal=Zoological Journal of the Linnean Society|doi=10.1093/zoolinnean/zlz008}}</ref>
====Reassigned species====
*''Globidens aegyptiacus'' Zdansky, 1935;<ref>Zdansky, O. 1935. The occurrence of mosasaurs in Egypt and in Africa in general. Bulletin de l’Institut d’Egypte 17: 83-94.</ref> now type species of ''[[Igdamanosaurus]]''.<ref name="Lingham-Soliar - Igdamanosaurus">{{cite journal|last1=Lingham-Soliar|first1=T.|title=Mosasaurs from the Upper Cretaceous of Niger|journal=Palaeontology|date=1991|volume=34|issue=3|pages=653–670}}</ref>
*''Globidens fraasi'' Dollo 1913; now type species of ''[[Carinodens]]''.<ref name=":0">{{Cite journal|last=Schulp|first=Anne S.|last2=Jagt|first2=John W. M.|last3=Fonken|first3=Frans|date=2004-09-10|title=New material of the mosasaur Carinodens belgicus from the Upper Cretaceous of the Netherlands|journal=Journal of Vertebrate Paleontology|volume=24|issue=3|pages=744–747|doi=10.1671/0272-4634(2004)024[0744:NMOTMC]2.0.CO;2|issn=0272-4634}}</ref>
*''Globidens timorensis'' Huene, 1935; reinterpreted as a [[Triassic]] [[Ichthyosauria|ichthyosaur]]<ref>{{Cite journal|author1=Eric W.A. Mulder |author2=John W.M. Jagt |year=2019 |title=''Globidens(?) timorensis'' E. VON HUENE, 1935: not a durophagous mosasaur, but an enigmatic Triassic ichthyosaur |journal=Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen |volume=293 |issue=1 |pages=107–116 |doi=10.1127/njgpa/2019/0835 }}</ref>
*''Globidens belgicus'' (Woodward, 1891) Kruytzer, 1961;<ref>Kruytzer, E.M. 1961. "Een nieuwe Mosasaurier voor ons land. ''Globidens belgicus'' (Woodward 1891). ''Natuurhistorisch Maandblad'' '''50''' (7-8): 72-73</ref> reinterpreted as a species of ''Carinodens''.
==Classification==
[[File:Globidens phosphaticus maastrichtian marocco.JPG|thumb|upright|''G. phosphaticus'' tooth]]
''Globidens'' resides within the subfamily [[Mosasaurinae]], which includes several mosasaur lineages, and within that, the Tribe [[Globidensini]], which also includes the genus ''[[Carinodens]]''.<ref name="Russel - New sp. of Globidens from SD">{{cite journal|last1=Russell|first1=Dale|title=A new species of ''Globidens'' from South Dakota, and a review of globidentine mosasaurs|journal=Fieldiana Geology|date=1975|volume=33|issue=13|pages=235–256}}</ref> ''Carinodens'' is thus regarded as a sister taxon of ''Globidens''.
Placement of ''Globidens'' and, to an extent, Mosasauridae in a phylogenetic tree is somewhat unclear and specific placement of genera varies between many morphological and molecular tests. It is generally agreed that Mosasauridae is a sister group to Pythonomorpha, which includes all snakes.<ref>Caldwell, M. W. 1999. Squamate phylogeny and the relationships of snakes and mosasauroids. Zoological Journal of the Linnean Society, 125(1):115-147</ref> Within Mosasauridae, ''Globidens'' is generally placed near ''Prognathodon'', although some placements of ''Prognathodon'' specimens are questionable.<ref name=Eremiasaurus />
Below is a [[cladogram]] of mosasaurs and related taxa modified from Aaron R. H. Leblanc, Michael W. Caldwell and Nathalie Bardet, 2012:<ref name=Eremiasaurus>{{cite journal |author=Aaron R. H. Leblanc, Michael W. Caldwell and Nathalie Bardet |year=2012 |title=A new mosasaurine from the Maastrichtian (Upper Cretaceous) phosphates of Morocco and its implications for mosasaurine systematics |journal=Journal of Vertebrate Paleontology |volume=32 |issue=1 |pages=82–104 |doi=10.1080/02724634.2012.624145}}</ref>
{{clade| style=font-size:85%;line-height:85%
|label1=[[Mosasaurinae]]
|1={{clade
|1=''[[Dallasaurus turneri]]''
|2={{clade
|1={{clade
|1=''[[Clidastes liodontus]]''
|2=''[[Clidastes moorevillensis]]''
|3=''[[Clidastes propython]]'' }}
|2={{clade
|1=''[[Prognathodon kianda|"Prognathodon" kianda]]''
|2={{clade
|1='''''Globidens alabamaensis'''''
|2='''''Globidens dakotensis'''''
|3={{clade
|label1=[[Mosasaurini]]
|1={{clade
|1=''[[Eremiasaurus heterodontus]]''
|2={{clade
|1=''[[Plotosaurus bennisoni]]''
|2={{clade
|1=''[[Mosasaurus conodon]]''
|2=''[[Mosasaurus hoffmanni]]''
|3=''[[Mosasaurus missouriensis]]'' }} }} }}
|2={{clade
|1=''[[Prognathodon rapax|"Prognathodon" rapax]]''
|2={{clade
|1=''[[Plesiotylosaurus crassidens]]''
|2={{clade
|1=''[[Prognathodon overtoni]]''
|2={{clade
|1=''[[Prognathodon saturator]]''
|2={{clade
|1=''[[Prognathodon waiparaensis]]''
|2={{clade
|1=''[[Prognathodon solvayi]]''
|2=''[[Prognathodon currii]]'' }} }} }} }} }} }} }} }} }} }} }}
}}
==Paleobiology==
[[Image:Globidens.jpg|thumb|Lateral and oblique, medial view of the left maxilla of ''G. alabamaensis'']]
''Globidens'' was uniquely adapted to take advantage of hard-shelled prey in comparison to other mosasaurs. In addition to a generally robust skull,<ref name="Russel - New sp. of Globidens from SD" /> its teeth are adapted for crushing rather than piercing or tearing. It is believed that ''Globidens'' was a durophagous predator, eating hard-shelled [[mollusks]] such as [[bivalves]] and [[ammonites]].<ref>Massare, J. A. 1987. Tooth Morphology and Prey Preference of Mesozoic Marine Reptiles. Journal of Vertebrate Paleontology, 7(2):121-137.</ref> Stomach contents of a specimen found in South Dakota support prior assumptions, showing the crushed shells of [[inoceramid]] clams.<ref>Martin, J. E. and Fox, J. E. 2007. Stomach contents of ''Globidens'', a shell-crushing mosasaur (Squamata), from the Late Cretaceous Pierre Shale Group, Big Bend area of the Missouri River, central South Dakota. Geological Society of America Special Papers, 427:167-176. {{doi|10.1130/2007.2427(12)}}</ref>
==Paleoecology==
''Globidens'', like other mosasaurs, lived in the warm, shallow seas of the Late Cretaceous, such as the [[Western Interior Seaway]] of North America. So far, ''Globidens'' has been discovered primarily in North America and in parts of northern and western Africa, such as Morocco and Angola, although specimens from the Middle East and eastern South America have been found as well.<ref name="Bardet - Durophages">{{cite journal|last1=Bardet|first1=N.|last2=Pereda Suberbiola|first2=X.|last3=Iarochene|first3=M.|last4=Amalik|first4=M.|last5=Bouya|first5=B.|title=Durophagous Mosasauridae (Squamata) from the Upper Cretaceous phosphates of Morocco, with description of a new species of Globidens|journal=Netherlands Journal of Geosciences|date=2005|volume=84|issue=3|pages=167–176|doi=10.1017/S0016774600020953|doi-access=free}}</ref><ref>Polcyn, M. J., Jacobs, L. L., Schulp, A. S., and Mateus, O. 2010. The North African Mosasaur ''Globidens phosphaticus'' from the Maastrichtian of Angola. Historical Biology, 22(3):175-185.</ref>
==See also==
{{Portal|Paleontology}}
*[[List of marine reptiles]]
==References==
{{Reflist|2}}
* Everhart, M.J. 2008. Rare occurrence of a ''Globidens'' sp. (Reptilia; Mosasauridae) dentary in the Sharon Springs Member of the Pierre Shale (Middle Campanian) of Western Kansas. p. 23-29 in Farley G. H. and Choate, J.R. (eds.), Unlocking the Unknown; Papers Honoring Dr. Richard Zakrzewski, Fort Hays Studies, Special Issue No. 2, 153 p., Fort Hays State University, Hays, KS.{{page needed|date=July 2012}}
* Huene, E. von. 1935. Mosasaurier-Zähne von Timor. Zentralblatt für Mineralogie, Geologie und Palaeontologie; in Verbindung mit den Neuen Jahrbuch für Mineralogie, Geologie und Palaeontologie. Stuttgart. Abt. B 10 412-416, 3 figs. (in German)
* Martin, J. E. 2007. A new species of the durophagous mosasaur, ''Globidens'' (Squamata: Mosasauridae) from the Late Cretaceous Pierre Shale Group of central South Dakota, USA. Pages 167-176 in Martin, J. E. and Parris D. C. (eds.), The Geology and Paleontology of the Late Cretaceous Marine Deposits of the Dakotas. Geological Society of America, Special Paper 427. (''Globidens schurmanni'')
* Russell, Dale A. 1975. A new species of ''Globidens'' from South Dakota. Fieldiana Geology, 33(13): 235-256. (Field Museum of Natural History)
{{Mosasauridae}}
{{Taxonbar|from=Q141401}}
{{Authority control}}
[[Category:Mosasaurines]]
[[Category:Mosasaurs of North America]]
[[Category:Fossil taxa described in 1912]]
[[Category:Mosasaurs of Asia]]
[[Category:Mosasaurs of Africa]]
[[Category:Taxa named by Charles W. Gilmore]]
[[Category:Mooreville Chalk]]
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