Hesperogavialis

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Hesperogavialis
Temporal range: Mid-Late Miocene (Mayoan-Huayquerian)
~11.6–7.246  Ma
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Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Crocodilia
Family: Gavialidae
Subfamily: Gryposuchinae
Genus: Hesperogavialis
Bocquetin and Buffetaut, 1981
Species
  • H. cruxentiBocquetin and Buffetaut, 1981 (type)
  • H. bocquentini ?

Hesperogavialis is an extinct genus of gryposuchine gavialid. Fossils have been found from Venezuela and Brazil that date back to the Middle to Late Miocene. [1] [2] Although Hesperogavialis is one of the best known gavialoids from South America, the posterior portion of the skull is still unknown, making any attempts at classification within the family somewhat more difficult than other gavialoids in which much of the skull is present. The genus possibly comprises three species. The type species, H. cruxenti, has been found in the Urumaco Formation in Venezuela. A second possible species, named H. bocquentini, has been described from the Solimões Formation in Acre, Brazil, and can be distinguished from H. cruxenti by the asymmetry seen in the anterior portion of the nasals and the small distance between alveoli. A third species can be recognized from the same locality in Acre, although a formal name has yet to be given to it. [3]

Phylogenetics

Although considered a South American gryposuchine, Hesperogavialis may actually have had closer relations to the extant Gavialis known from Asia. This has been concluded on the basis of a lack of a nasal-premaxillary contact on the rostrum that can be seen in the extinct South American gavialoids. The position of these bones bears a closer resemblance to Gavialis by being rather slender and extending from the orbits to the middle of the rostrum while being considerably separated from the premaxilla. [4] This close relationship suggests that there may have been multiple gavialid dispersal events from the Old World to South America. It has also been proposed that this is just an independently derived characteristic unique to Hesperogavialis among the gryposuchines, and that it does not suggest any relationship to Asian gavialoids. [5]

Related Research Articles

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<i>Melanosuchus</i> Genus of caiman

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<i>Purussaurus</i> Extinct genus of reptiles

Purussaurus is an extinct genus of giant caiman that lived in South America during the Miocene epoch, from the Colhuehuapian to the Montehermosan in the SALMA classification. It is known from skull material found in the Brazilian and Peruvian Amazon, Colombian Villavieja Formation, Panamanian Culebra Formation and the Urumaco and Socorro Formations of northern Venezuela.

Charactosuchus is an extinct genus of crocodilian. It was assigned to the family Crocodylidae in 1988. Specimens have been found in Colombia, Brazil, Jamaica, and possibly Florida and South Carolina. It was gharial-like in appearance with its long narrow snout but bore no relation to them, being more closely related to modern crocodiles than to gharials.

Eogavialis is an extinct genus of eusuchian crocodylomorph, usually regarded as a gavialoid crocodylian. It superficially resembles Tomistoma schlegelii, the extant false gharial, and consequently material from the genus was originally referred to Tomistoma. Indeed, it was not until 1982 that the name Eogavialis was constructed after it was realised that the specimens were from a more basal form.

<i>Eosuchus</i> Extinct genus of reptiles

Eosuchus is an extinct genus of eusuchian crocodylomorph, traditionally regarded as a gavialoid crocodilian. It might have been among the most basal of all gavialoids, lying crownward of all other known members of the superfamily, including earlier putative members such as Thoracosaurus and Eothoracosaurus. Fossils have been found from France as well as eastern North America in Maryland, Virginia, and New Jersey. The strata from which specimens have been found date back to the late Paleocene and early Eocene epochs.

<i>Gryposuchus</i> Extinct genus of gavialoid crocodilian

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Ikanogavialis is an extinct genus of gavialid crocodilian. Fossils have been found in the Urumaco Formation in Urumaco, Venezuela and the Solimões Formation of Brazil. The strata from which remains are found are late Miocene in age, rather than Pliocene as was once thought. A possible member of this genus survived into the Late Holocene on Muyua or Woodlark Island in Papua New Guinea.

Castillo Formation, Venezuela

The Castillo Formation is an Early Miocene geologic formation in the Falcón Basin of Venezuela. The formation unconformably overlies the Matatere, Misoa, El Paují and Jarillal Formations. The Castillo Formation is overlain by Quaternary alluvium and in places by the Capadare Formation. The formation, deposited in a calm near-shore lagoonal brackish environment, with possibly fluvial influence, has provided a rich assemblage of fossil crocodylians, turtles, giant sloths and various types of fish.

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Siquisiquesuchus is an extinct genus of gavialid crocodilian. It is known from cranial remains and a few postcranial bones found in Miocene-age rocks of the Castillo Formation in northwestern Venezuela.

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Globidentosuchus is an extinct genus of basal caimanine crocodylian known from the late Middle to Late Miocene of the Middle and the Upper Members of the Urumaco Formation at Urumaco, Venezuela. Its skull was very short and robust, with large units of spherical teeth used to break the shells of molluscs as part of its durophagus diet. It is thought to be one of the most basal Caimanines, even sharing some traits with alligatorids.

<i>Caiman wannlangstoni</i> Extinct species of reptile

Caiman wannlangstoni is an extinct species of caiman that lived in what is now the Amazon Basin and surrounding areas during the Middle and Late Miocene. Fossils of C. wannlangstoni have been found in the Pebas Formation near Iquitos in Peru and include partial skulls and isolated skull bones. Other fossils were uncovered from the Urumaco Formation in Venezuela and the Laventan Honda Group of Colombia. The species was first described in 2015. Features that in combination distinguish C. wannlangstoni from other caimans include a deep snout, a wavy upper jaw margin, a large and upward-directed narial opening, and blunt teeth at the back of the jaws. Based on the sizes of the skulls, its estimated body length is about 211 to 227 centimetres.

The Urumaco Formation is a formation in Venezuela that includes deposits from the Late Miocene. It is the site of several "giant forms": the turtles, crocodiles, sloths and rodents of Urumaco are among the largest of their groups.

Caiman brevirostris is an extinct species of caiman described in 1987 on the basis of an incomplete rostrum and partial right mandible that was collected from the Miocene age Solimões Formation of Acre, Brazil.

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Dadagavialis is an extinct monospecific genus of gavialid crocodylian that lived during the Early Miocene in what is now Panama. It was described in 2018, and was proposed to be a member of Gryposuchinae. However, other studies have shown Gryposuchinae to be paraphyletic and rather an evolutionary grade towards the living gharial, and thus Dadagavialis might just be classified as a member of Gavialidae.

References

  1. Bocquetin, J. C. and Buffetaut, E. (1981). Hesperogavialis cruxenti n. gen., n. sp., nouveau gavialide (Crocodylia, Eusuchia) du Miocène Supériur (Huayquerien) d'Urumaco (Venezuela). Geobios14:415-419.
  2. Souza-Filho, J. P., Bocquetin, J. C., and Negri, F. R. (1993). Um crâneo de Hesperogavialis sp. (Crocodylia, Gavialidae) Mioceno Superior — Plioceno do Estado do Acre, Brasil. Ameghiniana30:341-342.
  3. Souza-Filho, J. P. (1999). New crocodylian fossils (Alligatoridae and Gavialidae) from the Cenozoic, Acre State, Brazil. Ameghiniana36(Supplement to Number 4)
  4. Brochu, C. A. and Rincón, A. D. (2004). A gavialoid crocodylian from the lower Miocene of Venezuela. In: Sánchez-Villagra, M. R., Clack, J. A., and Batten, D. J., eds., Fossils of the Miocene Castillo Formation, Venezuela: contributions on neotropical palaeontology. Special Papers in Palaeontology No. 71, The Palaeontological Association (London), p. 61-79.
  5. Langston, W. and Gasparini, Z. (1997). Crocodilians, Gryposuchus, and the South American gavials. In: Kay, R. F., Madden, R. H, Cifelli, R. L., and Flynn, J. J., eds., Vertebrate paleontology in the neotropics. Smithsonian Institution Press; Washington, DC. pp. 113-154.