Ikanogavialis
Encyclopedia
Ikanogavialis is an extinct genus
of gryposuchine
gavialoid
crocodilia
n. Fossil
s have been found from the Urumaco Formation of Venezuela
. The strata from which remains are found are late Miocene
in age, rather than Pliocene
as was once thought.
ry alveoli. The external nares projected anterodorsally from the rostrum. This can be seen as a plesiomorphic characteristic in crocodilians, but given that the earliest gavialoids possessed dorsally projecting external nares, this feature can be seen as having been a reversal from the gavialoid apomorphy back to the crocodilian plesiomorphy rather than having been directly obtained from an early crocodilian ancestor.
of Ikanogavialis is I. gameroi. It was named in 1970 from material found from the Urumaco Formation. A Pleistocene
gavialoid named Gavialis papuensis from Murua, part of the Solomon Islands
, bears some vague similarities with Ikanogavialis and was referred to the genus in 1999, along with other slender-snouted forms from the Neogene of South America and Africa. This is not widely accepted.
. The strata of the Urumaco Formation were deposited in both marine and fluvial settings, although it is unclear to which portion both genera belong. Other gavialoids such as Siquisiquesuchus
and Piscogavialis
are known to have lived in coastal environments, and it is likely that extant freshwater gavialoids such as Gavialis may have originated from these coastal forms. Ikanogavialis also existed with many other crocodilians in Venezuela during the late Miocene including the giant caiman
Purussaurus
and an extinct species of Melanosuchus.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of gryposuchine
Gryposuchinae
Gryposuchinae is an extinct subfamily of gavialid crocodylians. Gryposuchines lived mainly in South America during the Oligocene and Miocene epochs. Most were long-snouted coastal forms. The group was named in 2007 and includes genera such as Gryposuchus and Aktiogavialis.-Description:Gryposuchines...
gavialoid
Gavialoidea
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 possibly the False gharial Tomistoma schlegelii are alive today.-Classification:Gavialoidea contains the...
crocodilia
Crocodilia
Crocodilia is an order of large reptiles that appeared about 84 million years ago in the late Cretaceous Period . They are the closest living relatives of birds, as the two groups are the only known survivors of the Archosauria...
n. Fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s have been found from the Urumaco Formation of Venezuela
Venezuela
Venezuela , officially called the Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It borders Colombia to the west, Guyana to the east, and Brazil to the south...
. The strata from which remains are found are late Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
in age, rather than Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
as was once thought.
Description
Ikanogavialis had a dorsoventrally deep snout and a distinctive notch between the dentary and maxillaMaxilla
The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
ry alveoli. The external nares projected anterodorsally from the rostrum. This can be seen as a plesiomorphic characteristic in crocodilians, but given that the earliest gavialoids possessed dorsally projecting external nares, this feature can be seen as having been a reversal from the gavialoid apomorphy back to the crocodilian plesiomorphy rather than having been directly obtained from an early crocodilian ancestor.
Species
The type speciesType species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
of Ikanogavialis is I. gameroi. It was named in 1970 from material found from the Urumaco Formation. A Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
gavialoid named Gavialis papuensis from Murua, part of the Solomon Islands
Solomon Islands
Solomon Islands is a sovereign state in Oceania, east of Papua New Guinea, consisting of nearly one thousand islands. It covers a land mass of . The capital, Honiara, is located on the island of Guadalcanal...
, bears some vague similarities with Ikanogavialis and was referred to the genus in 1999, along with other slender-snouted forms from the Neogene of South America and Africa. This is not widely accepted.
Paleobiology
Ikanogavialis may have lived in a coastal paleoenvironment along with other gavialids such as GryposuchusGryposuchus
Gryposuchus is an extinct genus of gavialoid crocodilian. It is the type genus of the subfamily Gryposuchinae. Fossils have been found from Argentina, Colombia, Venezuela, Brazil and the Peruvian Amazon. The genus existed during the early and middle Miocene epoch. One recently described species, G...
. The strata of the Urumaco Formation were deposited in both marine and fluvial settings, although it is unclear to which portion both genera belong. Other gavialoids such as Siquisiquesuchus
Siquisiquesuchus
Siquisiquesuchus is an extinct genus of gavialoid crocodilian...
and Piscogavialis
Piscogavialis
Piscogavialis is an extinct genus of gryposuchine gavialid crocodylian. The only species yet known is P. jugaliperforatus. Fossils of Piscogavialis have been found from the Mio-Pliocene Pisco Formation of the Sacaco Basin in southern Peru...
are known to have lived in coastal environments, and it is likely that extant freshwater gavialoids such as Gavialis may have originated from these coastal forms. Ikanogavialis also existed with many other crocodilians in Venezuela during the late Miocene including the giant caiman
Caiman
Caimans are alligatorid crocodylians within the subfamily Caimaninae. The group is one of two subfamilies of the family Alligatoridae, the other being alligators. Caimans inhabit Central and South America. They are relatively small crocodilians, with most species reaching lengths of only a few...
Purussaurus
Purussaurus
Purussaurus is an extinct genus of giant caiman that lived in South America during the Miocene epoch, 8 million years ago. It is known from skull material found in the Brazilian, Colombian and Peruvian Amazonia, and northern Venezuela. The estimated skull length for one large individual of the type...
and an extinct species of Melanosuchus.
External links
- Ikanogavialis in the Paleobiology DatabasePaleobiology Database' is an online resource for information on the distribution and classification of fossil animals, plants, and microorganisms.-History:The Paleobiology Database was founded in 2000. It has been funded by the National Science Foundation and the Australian Research Council...