Globidens

Last updated

Globidens
Temporal range: Late Cretaceous, 84.9–66  Ma
Globidens NMNH.jpg
Reconstructed skull of G. phosphaticus, National Museum of Natural History
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Clade: Mosasauria
Family: Mosasauridae
Tribe: Globidensini
Genus: Globidens
Gilmore, 1912
Species
  • G. alabamaensis(Type)
    Gilmore, 1912
  • G. dakotensisRussell, 1975
  • G. hisaensisKaddumi, 2009
  • G. phosphaticusBardet and Pereda-Suberbiola, 2005
  • G. schurmanniMartin, 2007
  • G. simplexLeBlanc et al., 2019

Globidens ("Globe teeth") is an extinct genus of mosasaurid 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, Morocco, Syria and the United States. [1] Among mosasaurs, Globidens is probably most well known for the highly rounded, globe-like teeth that give it its name.

Contents

Globidens alabamaensis was the first species of Globidens described, in a publication by Charles W. Gilmore (1912). It is used as the type specimen for Globidens.

Description

Life restoration of G. alabamaensis GlobidensDB2.jpg
Life restoration of G. alabamaensis

Globidens was a relatively medium-sized mosasaur, measuring about 5–6 metres (16–20 ft) long. [2] It was similar in appearance to other mosasaurs, with its streamlined body, flippers, a laterally flattened tail, and powerful jaws. 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 turtles, ammonites, nautili, and bivalves. 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 ).

Reconstructed skull of G. dakotensis Globidens dakotensis skull.jpg
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. [3] 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 teeth on the roof of its mouth. [3]

History of discovery

Skull of G. dakotensis (bottom view), Field Museum of Natural History Globidens FMNH.jpg
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. [4]

Since Gilmore's identification of Globidens, several other species have been identified, including G. dakotensis (Russel 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. [5]

Species

Holotype maxilla (USNM 6527.jpg) of G. alabamaensis Left maxilla of holotype of Globidens, USNM 6527.jpg
Holotype maxilla (USNM 6527.jpg) of G. alabamaensis

Reassigned species

Classification

G. phosphaticus tooth Globidens phosphaticus maastrichtian marocco.JPG
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 . [3] 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. [12] Within Mosasauridae, Globidens is generally placed near Prognathodon, although some placements of Prognathodon specimens are questionable. [13]

Below is a cladogram of mosasaurs and related taxa modified from Aaron R. H. Leblanc, Michael W. Caldwell and Nathalie Bardet, 2012: [13]

Mosasaurinae

Paleobiology

Lateral and oblique, medial view of the left maxilla of G. alabamaensis Globidens.jpg
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, [3] 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. [14] Stomach contents of a specimen found in South Dakota support prior assumptions, showing the crushed shells of inoceramid clams. [15]

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. [6] [16]

See also

Related Research Articles

<span class="mw-page-title-main">Mosasaur</span> Extinct marine lizards of the Late Cretaceous

Mosasaurs are an extinct group of large aquatic reptiles within the family Mosasauridae that lived during 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.

<i>Mosasaurus</i> Extinct genus of marine squamate reptile from the Late Cretaceous

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 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 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.

Tylosaurus is a genus of russellosaurine mosasaur that lived about 92 to 66 million years ago during the Turonian to Maastrichtian stages of the Late Cretaceous. Its fossils have been found primarily around North Atlantic Ocean including in North America, Europe, and Africa.

<span class="mw-page-title-main">Mosasaurinae</span> Subfamily of reptiles

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.

<i>Prognathodon</i> Extinct genus of lizards

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.

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.

Carinodens is an extinct genus of Cretaceous marine lizard belonging to the mosasaur family. "Carinodens" means "keel teeth" and was named in 1969 as a replacement name for Compressidens, "compressed teeth", which was already in use for a gadilidan scaphopod mollusk.

<i>Pluridens</i> Extinct genus of lizards

Pluridens is an extinct genus of marine lizard belonging to the Mosasauridae. Pluridens is placed in the subfamily Halisaurinae with the genera Phosphorosaurus, Eonatator and Halisaurus. Compared to related halisaurines, Pluridens had longer jaws with more teeth, and smaller eyes. It also grew large size, measuring 5–6 m (16–20 ft) long and perhaps over 9 m (30 ft) in some individuals. The jaws in some specimens are robust, and sometimes show injuries suggestive of combat. The jaws may have been used for fighting over mates or territories.

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.

<i>Liodon</i> Extinct genus of lizards

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.

<i>Plesiotylosaurus</i> Extinct genus of lizards

Plesiotylosaurus, meaning "near Tylosaurus", 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. The genus contains one species, Plesiotylosaurus crassidens, recovered from deposits of Middle Maastrichtian age in the Moreno Formation in California.

Eremiasaurus is a genus of mosasaurs, an extinct group of marine reptiles. It lived during the Maastrichtian stage of the Late Cretaceous in what is now North Africa. Only one species is known, E. heterodontus, described in 2012 from two remarkably complete fossil specimens discovered in the Ouled Abdoun Basin, Morocco. This site is known to have delivered a significant number of other related mosasaurs.

<span class="mw-page-title-main">Timeline of mosasaur research</span>

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.

<i>Kaikaifilu</i> Extinct genus of marine squamate reptiles

Kaikaifilu is an extinct genus of large mosasaurs that lived during the Maastrichtian stage of the Late Cretaceous, in what is now northern Antarctica. The only species known, K. hervei, was described in 2017 from an incomplete specimen discovered in the López de Bertodano Formation, in Seymour Island, Antarctic Peninsula. The taxon is named in reference to Coi Coi-Vilu, a reptilian ocean deity of the Mapuche cosmology. Early observations of the holotype classify it as a member of the subfamily Tylosaurinae. However, later observations note that several characteristics show that this attribution is problematic.

<span class="mw-page-title-main">Globidensini</span> Tribe of lizards

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, Carinodens, Igdamanosaurus, Harranasaurus and Xenodens. Features of 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.

<i>Xenodens</i> Extinct genus of lizards

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.

<i>Thalassotitan</i> Large bodied African mosasaur

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.

References

  1. 1 2 Polcyn, Michael J.; Jacobs, Louis L.; Schulp, Anne S.; Mateus, Octávio (1 March 2010). "The North African Mosasaur Globidens phosphaticus from the Maastrichtian of Angola". Historical Biology. 22 (1–3): 175–185. doi:10.1080/08912961003754978.
  2. Cooper, S.L.A.; Marson, K.J.; Smith, R.E.; Martill, D. (2022). "Contrasting preservation in pycnodont fishes reveals first record of regurgitalites from the Upper Cretaceous (Maastrichtian) Moroccan phosphate deposits". Cretaceous Research. 131 (4). 105111. doi:10.1016/j.cretres.2021.105111.
  3. 1 2 3 4 5 6 Russel, Dale (1975). "A new species of Globidens from South Dakota, and a review of globidentine mosasaurs". Fieldiana Geology. 33 (13): 235–256.
  4. Gilmore, Charles W. (1912). "A new mosasauroid reptile from the Cretaceous of Alabama" (PDF). Proceedings of the United States National Museum. 41 (1870): 479–484.
  5. 1 2 Lingham-Soliar, T. (1991). "Mosasaurs from the Upper Cretaceous of Niger". Palaeontology. 34 (3): 653–670.
  6. 1 2 Bardet, N.; Pereda Suberbiola, X.; Iarochene, M.; Amalik, M.; Bouya, B. (2005). "Durophagous Mosasauridae (Squamata) from the Upper Cretaceous phosphates of Morocco, with description of a new species of Globidens". Netherlands Journal of Geosciences. 84 (3): 167–176. doi: 10.1017/S0016774600020953 .
  7. Kaddumi, Hani F. (2009). "A new species of Globidens (Squamata: Mosasauridae) from the late Campanian-early Maastrichtian of Jordan". Fossils of the Harrana Fauna and the Adjacent Areas. Amman: Eternal River Museum of Natural History. OCLC   709582892.
  8. LeBlanc, Aaron; Mohr, Sydney; Caldwell, Michael (2019). "Insights into the anatomy and functional morphology of durophagous mosasaurines (Squamata: Mosasauridae) from a new species of Globidens from Morocco". Zoological Journal of the Linnean Society. doi:10.1093/zoolinnean/zlz008.
  9. Zdansky, O. 1935. The occurrence of mosasaurs in Egypt and in Africa in general. Bulletin de l’Institut d’Egypte 17: 83-94.
  10. Schulp, Anne S.; Jagt, John W. M.; Fonken, Frans (2004-09-10). "New material of the mosasaur Carinodens belgicus from the Upper Cretaceous of the Netherlands". Journal of Vertebrate Paleontology. 24 (3): 744–747. doi:10.1671/0272-4634(2004)024[0744:NMOTMC]2.0.CO;2. ISSN   0272-4634.
  11. Eric W.A. Mulder; John W.M. Jagt (2019). "Globidens(?) timorensis E. VON HUENE, 1935: not a durophagous mosasaur, but an enigmatic Triassic ichthyosaur". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen. 293 (1): 107–116. doi:10.1127/njgpa/2019/0835.
  12. Caldwell, M. W. 1999. Squamate phylogeny and the relationships of snakes and mosasauroids. Zoological Journal of the Linnean Society, 125(1):115-147
  13. 1 2 Aaron R. H. Leblanc, Michael W. Caldwell and Nathalie Bardet (2012). "A new mosasaurine from the Maastrichtian (Upper Cretaceous) phosphates of Morocco and its implications for mosasaurine systematics". Journal of Vertebrate Paleontology. 32 (1): 82–104. doi:10.1080/02724634.2012.624145.
  14. Massare, J. A. 1987. Tooth Morphology and Prey Preference of Mesozoic Marine Reptiles. Journal of Vertebrate Paleontology, 7(2):121-137.
  15. 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)
  16. 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.