Aktiogavialis

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Aktiogavialis
Temporal range: Oligocene-Miocene, 28–6.8  Ma
Puertoricocroc.png
An image (A) and a drawing (B) of the underside of the skull of Aktiogavialis puertoricensis
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Crocodilia
Family: Gavialidae
Subfamily: Gryposuchinae
Genus: Aktiogavialis
Vélez-Juarbe et al., 2007
Species

Aktiogavialis is an extinct genus of crocodylian that lived from the Oligocene until the Miocene in what is now the Caribbean. Two species have been described: Aktiogavialis puertoricensis from the Middle Oligocene of Puerto Rico and Aktiogavialis caribesi from the Huayquerian of the Late Miocene of Venezuela. [1] [2]

As a typical gavialoid, Aktiogavialis followed the standard crocodilian body plan. An elongated, squat quadrupedal body terminated in a long, laterally flattened tail at one end, and a specialized, narrow snout at the other. As with the other members of its family, the snout of Aktiogavialis was extremely long and narrow, tapering into a thin structure past the eye sockets. Based on the fragmentary remains recovered, the species was differentiated from other members of its family by unique positioning and geometry of its skull elements. [1] Phylogenetic analysis indicates its closest relatives were the extinct gavials Gryposuchus and Siquisiquesuchus . [1]

The type species of the genus, A. puertoricensis, was described in 2007. The holotype, designated UPRMP 3094, was discovered in Puerto Rican deposits dating around 28 million years old, from the Middle to Late Oligocene. The deposits, part of the San Sebastián Formation along the Río Guatemala in Puerto Rico, have been an adequate supply of other crocodylian fossils. Aktiogavialis remains recovered were extremely fragmentary, consisting of an incomplete skull featuring elements of the braincase and other scattered cranial elements. [1]

Marine sediments and nanofossils form part of the deposits where the specimen was found, indicating a marine distribution for A. puertoricensis. This is in contrast with the living gavialoids, which reside entirely in the freshwater rivers of South Asia. [3] [4] While fossils found in prehistoric deltaic sediments possibly have been washed onto the delta from inland sources, the Aktiogavialis specimen found so far was from a location that had essentially been islandic. This has led to conclusions that gavialoids were partially or primarily saltwater reptiles prior to the evolution of the group's one or two extant species. [1]

The genus' name, Aktiogavialis, is derived from the Greek words aktios (river) and gavialis (gavial). This roughly translates to "shore gavial", referring to its rather estuarine distribution. The specific name puertoricensis means "from Puerto Rico", in reference to the specimen's country of origin. [1]

Related Research Articles

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

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

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Gryposuchinae is an extinct subfamily of gavialid crocodylians. Gryposuchines lived mainly in the Miocene of South America. However, "Ikanogavialis" papuensis may have survived more recently, into the Late Pleistocene/Holocene. Most were long-snouted coastal forms. The group was named in 2007 and includes genera such as Gryposuchus and Aktiogavialis, although a 2018 study indicates that the group might be paraphyletic and rather an evolutionary grade towards the gharial.

Gavialoidea Superfamily of large reptiles

Gavialoidea is one of three superfamilies of crocodylians, the other two being Alligatoroidea and Crocodyloidea. Although many extinct species are known, only the gharial Gavialis gangeticus and the false gharial Tomistoma schlegelii are alive today, with Hanyusuchus having become extinct in the last few centuries.

Tomistominae Subfamily of reptiles

Tomistominae is a subfamily of crocodylians that includes one living species, the false gharial. Many more extinct species are known, extending the range of the subfamily back to the Eocene epoch. In contrast to the false gharial, which is a freshwater species that lives only in southeast Asia, extinct tomistomines had a global distribution and lived in estuaries and along coastlines.

Tomistoma cairense is an extinct species of gavialoid crocodilian from the Lutetian stage of the Eocene era. It lived in North East Africa, especially Egypt. Remains of T. cairense have been found in the Mokattam Formation, in Mokattam, Egypt. Tomistoma cairense did not have a Maxilla process within their lacrimal gland, whereas all extant (living) crocodilians do.

Sacacosuchus is a genus of marine gharial that lived along the coast of the south-east Pacific from approximately 19 to 6.3 million years ago. Its fossils have been found in the Chilcatay and Pisco Formations of Peru, where it coexisted with the much larger Piscogavialis. Based on its skull, Sacacosuchus was most likely a generalist feeder with an estimated total body length of 4.32 m (14.2 ft). Its extinction is thought to have been caused by a combination of factors including falling sea levels and global cooling.

References

  1. 1 2 3 4 5 6 Vélez-Juarbe, Jorge; Brochu, Christopher A.; Santos, Hernán (2007-03-06). "A gharial from the Oligocene of Puerto Rico: transoceanic dispersal in the history of a non-marine reptile". Proceedings of the Royal Society. The Royal Society. 274 (1615): 1245–54. doi:10.1098/rspb.2006.0455. PMC   2176176 . PMID   17341454.
  2. Rodolfo Salas-Gismondi; Jorge W. Moreno-Bernal; Torsten M. Scheyer; Marcelo R. Sánchez-Villagra; Carlos Jaramillo (2018). "New Miocene Caribbean gavialoids and patterns of longirostry in crocodylians". Journal of Systematic Palaeontology. 17 (12): 1049–1075. doi:10.1080/14772019.2018.1495275. S2CID   91495532.
  3. "Gharial". WWF-India. World Wide Fund for Nature. 2008-07-22. Archived from the original on 2008-12-20. Retrieved 2008-12-26.
  4. "Gharial - Habitat & Distribution". WWF-India. World Wide Fund for Nature. 2008-01-25. Archived from the original on October 5, 2008. Retrieved 2008-12-26.

Bibliography