Gryposuchinae
Encyclopedia
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
.
) or Tomistoma schlegelii (the False gharial
). Other gavialoids from the Americas include thoracosaurs from the Late Cretaceous
and Paleocene
and long-snouted tomistomines
from the Eocene
, but neither of these groups are closely related to gryposuchines. The relationship of tomistomines in particular is unclear, as they have also been classified as crocodile
s.
A phylogenetic analysis conducted in the 2007 study found Gryposuchinae to include the genera Aktiogavialis, Gryposuchus, Ikanogavialis
, Piscogavialis
, and Siquisiquesuchus
. Below is a cladogram
from the 2007 analysis showing the phylogenetic relationships of gryposuchines among gavialoids
:
, a basal gavialid, is known from both marine and non-marine deposits in Egypt
. If it was a coastal animal, it may have been similar to the ancestor of later gavialids including gryposuchines.
The origin of gryposuchines is unclear. Earlier gavialids that were their probable ancestors are known from Africa and Asia. Traditionally, an African origin has been favored because gavialids would have been more likely to cross the Atlantic Ocean
than the longer expanses of the Pacific Ocean
. Moreover, warm equatorial currents run across the Atlantic from Africa to the Americas, assisting in travel. The presence Aktiogavialis in the Caribbean supports an Atlantic migration. Being the oldest known gryposuchine, Aktiogavialis was likely in the closest position to the time and location of the radiation.
Gavialidae
Gavialidae is a family of reptiles within the order Crocodilia. Gavialidae consists of only one surviving species, the gharial , which is native to India. Many extinct species are also known...
crocodylians. Gryposuchines lived mainly in South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
during the Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
and 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...
epochs. Most were long-snouted coastal forms. The group was named in 2007 and includes genera such as Gryposuchus
Gryposuchus
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...
and Aktiogavialis
Aktiogavialis
Aktiogavialis is an extinct genus of crocodylian from the Oligocene Epoch some thirty million years ago. Only one species in the genus, Aktiogavialis puertoricensis, has been described so far....
.
Description
Gryposuchines have long, narrow snouts and protruding eye sockets. One distinguishing feature of the group is the lack of a large exposure of the prootic bone around the trigeminal foramen, a hole in the side of the braincase wall.Classification
Gryposuchinae was named in 2007 as a subfamily of closely related gavialid crocodilians. It was defined as a stem-based taxon including Gryposuchus jessei and all crocodilians more closely related to it than to Gavialis gangeticus (the gharialGharial
The gharial , , also called Indian gavial or gavial, is the only surviving member of the once well-represented family Gavialidae, a long-established group of crocodilians with long, slender snouts...
) or Tomistoma schlegelii (the False gharial
False gharial
The false gharial , also known as the Malayan gharial, false gavial, or Tomistoma is a freshwater crocodile of the Crocodylidae family with a very thin and elongated snout...
). Other gavialoids from the Americas include thoracosaurs from the Late Cretaceous
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
and Paleocene
Paleocene
The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...
and long-snouted tomistomines
Tomistominae
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...
from the Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
, but neither of these groups are closely related to gryposuchines. The relationship of tomistomines in particular is unclear, as they have also been classified as crocodile
Crocodile
A crocodile is any species belonging to the family Crocodylidae . The term can also be used more loosely to include all extant members of the order Crocodilia: i.e...
s.
A phylogenetic analysis conducted in the 2007 study found Gryposuchinae to include the genera Aktiogavialis, Gryposuchus, Ikanogavialis
Ikanogavialis
Ikanogavialis is an extinct genus of gryposuchine gavialoid crocodilian. Fossils 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....
, 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...
, and Siquisiquesuchus
Siquisiquesuchus
Siquisiquesuchus is an extinct genus of gavialoid crocodilian...
. Below is a cladogram
Cladogram
A cladogram is a diagram used in cladistics which shows ancestral relations between organisms, to represent the evolutionary tree of life. Although traditionally such cladograms were generated largely on the basis of morphological characters, DNA and RNA sequencing data and computational...
from the 2007 analysis showing the phylogenetic relationships of gryposuchines among gavialoids
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...
:
Paleobiology
Based on the deposits in which they were found, most gryposuchines lived along coastlines. This distinguishes them from Asian gavialids like the gharial, which live only in freshwater. The ancestors of both gryposuchines and Asian gavialids were probably also coastal animals. EogavialisEogavialis
Eogavialis is an extinct gavialoid. It superficially resembles Tomistoma schlegelii, the extant false gharial, and consequently material from the genus was originally referred to Tomistoma...
, a basal gavialid, is known from both marine and non-marine deposits in Egypt
Egypt
Egypt , officially the Arab Republic of Egypt, Arabic: , is a country mainly in North Africa, with the Sinai Peninsula forming a land bridge in Southwest Asia. Egypt is thus a transcontinental country, and a major power in Africa, the Mediterranean Basin, the Middle East and the Muslim world...
. If it was a coastal animal, it may have been similar to the ancestor of later gavialids including gryposuchines.
The origin of gryposuchines is unclear. Earlier gavialids that were their probable ancestors are known from Africa and Asia. Traditionally, an African origin has been favored because gavialids would have been more likely to cross the Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
than the longer expanses of the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
. Moreover, warm equatorial currents run across the Atlantic from Africa to the Americas, assisting in travel. The presence Aktiogavialis in the Caribbean supports an Atlantic migration. Being the oldest known gryposuchine, Aktiogavialis was likely in the closest position to the time and location of the radiation.