''Prionosuchus'' is an extinct

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of large

temnospondyl Temnospondyli (from Greek language, Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') or temnospondyls is a diverse ancient order (biology), order of small to giant tetrapods—often considered Labyrinth ...

. A single

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

''P. plummeri'', is recognized from the

Early Permian 01 or 01 may refer to: * The year 2001, or any year ending with 01 * The month of January * 1 (number) Music * '01 (Richard Müller album), ''01'' (Richard Müller album), 2001 * 01 (Urban Zakapa album), ''01'' (Urban Zakapa album), 2011 * ''01011 ...

(some time between 299 and 272 million years ago). Its

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

s have been found in what is now northeastern

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

Description

The fragmentary remains of this animal have been found in the

Pedra de Fogo Formation The Pedra de Fogo Formation is an Early Permian ( Kungurian) geological formation of the Parnaíba Basin, northeastern Brazil. It has outcrops mainly on the states of Maranhão and Piauí, as well as some in Tocantins. It is thought to have bee ...

in the Parnaíba Basin of Northeastern Brazil, in the states of

Piauí Piauí ( ) is one of the states of Brazil, located in the country's Northeast Region, Brazil, Northeast Region. The state has 1.6% of the Brazilian population and produces 0.7% of the Brazilian GDP. Piauí has the shortest coastline of any coas ...

and

Maranhão Maranhão () is a States of Brazil, state in Brazil. Located in the country's Northeast Region, Brazil, Northeast Region, it has a population of about 7 million and an area of and it is divided into 217 municipalities. Clockwise from north, it ...

, and it was described by L.I. Price in 1948. The incomplete skull of the

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

specimen has been estimated to be long.Cox, C.B., and Hutchinson, P. (1991)
"Fishes and amphibians from the Late Permian Pedra de Fogo Formation of Northern Brazil".
''Palaeontology'', 34(3): 561–573. Several more fragmentary specimens have been found. One very fragmentary but very large specimen (BMNH R12005) appears to have come from an individual nearly three times the size of most other specimens, and may have had a skull that measured up to long. Based on related species and comparisons with living gharials, the total body length of this specimen has been estimated to reach greater than long. With an elongated and tapered snout, numerous sharp teeth, long body, short legs, and a tail adapted for swimming, its general appearance was very similar to a modern

gharial The gharial (''Gavialis gangeticus''), also known as gavial or fish-eating crocodile, is a crocodilian in the family (biology), family Gavialidae and among the longest of all living crocodilians. Mature females are long, and males . Adult males ...

or gar, and it probably had a similar lifestyle as an ambush aquatic predator feeding on fish and other aquatic animals. A study on the closely related ''

Archegosaurus ''Archegosaurus'' is a genus of temnospondyl amphibian which lived during the Asselian to Wuchiapingian stages of the Permian, around 299-253 million years ago. The remains of this animal, consisting of at least 90 partial skeletons (mostly skull ...

'' shows that it had a heat balance, gas exchange, osmoregulation, and digestion process more similar to that of

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

than modern aquatic amphibians; the same probably applied to ''Prionosuchus'' as well.

Classification

''Prionosuchus'' has been classified as an archegosaurid by Carroll. The genus is

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

with ''P. plummeri'' being the only species described. The archegosaurs were a group of

temnospondyls Temnospondyli (from Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') or temnospondyls is a diverse ancient order of small to giant tetrapods—often considered primitive amphibians—that flourished wo ...

that occupied the ecological niche of crocodiles and

alligator An alligator, or colloquially gator, is a large reptile in the genus ''Alligator'' of the Family (biology), family Alligatoridae in the Order (biology), order Crocodilia. The two Extant taxon, extant species are the American alligator (''A. mis ...

s during the Permian, and of which the European genus ''

'' is typical. The group became extinct at the end of the Permian and the niche was subsequently filled by other, new temnospondyls, later joined by reptiles such as the phytosaurs in the

Triassic The Triassic ( ; sometimes symbolized 🝈) is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is t ...

period. Cox and Hutchinson re-evaluated ''Prionosuchus'' in 1991 and synonymized it with the genus '' Platyoposaurus'' from Russia. On the basis of this study, the Pedra de Fogo Formation was reevaluated to be of Middle to Late Permian age. However, studies based on plants and pollens indicate that this formation is actually early Permian in age, making ''Prionosuchus'' not contemporary with ''Platyoposaurus''. More recent research rejects the later Permian date.Juan C. Cisneros, Claudia Marsicano, Kenneth D. Angielczyk, Roger M. H. Smith, Martha Richter, Jörg Fröbisch, Christian F. Kammerer & Rudyard W. Sadleir, 2015
New Permian fauna from tropical Gondwana
Nature Communications volume 6, Article number: 8676 (2015)

Paleoecology

''Prionosuchus'' lived in a humid and tropical environment as indicated by the petrified forest of the Pedra de Fogo Formation in which fossils of this animal have been found. The strata composed of

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility. Although its permeabil ...

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of Clay mineral, clay minerals (hydrous aluminium phyllosilicates, e.g., Kaolinite, kaolin, aluminium, Al2Silicon, Si2Oxygen, O5(hydroxide, OH)4) and tiny f ...

s and

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

s were deposited in

lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') an ...

al and

fluvial A river is a natural stream of fresh water that flows on land or inside caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of its course if it ru ...

environments. Other animals discovered in the same formation include other amphibians ('' Procuhy'', '' Timonya'', and a rhinesuchid),

captorhinids Captorhinidae is an extinct family of tetrapods, traditionally considered primitive reptiles, known from the late Carboniferous to the Late Permian. They had a cosmopolitan distribution across Pangea. Description Captorhinids are a clade of sm ...

(''Captorhinikos'' and other two unnamed taxa),

parareptile Parareptilia ("near-reptiles") is an extinct group of Basal (phylogenetics), basal Sauropsida, sauropsids ("Reptile, reptiles"), traditionally considered the sister taxon to Eureptilia (the group that likely contains all living reptiles and birds ...

('' Karutia'') and fish including chondrichthyans (''Rubencanthus'', '' Sphenacanthus'', ''Bythiacanthus'', ''Taquaralodus'', ''Itapyrodus'', '' Anisopleurodontis''), palaeoniscids ('' Brazilichthys''), and

lungfish Lungfish are freshwater vertebrates belonging to the class Dipnoi. Lungfish are best known for retaining ancestral characteristics within the Osteichthyes, including the ability to breathe air, and ancestral structures within Sarcopterygii, inc ...

References

{{Taxonbar, from=Q2341275 Prehistoric amphibian genera Cisuralian temnospondyls Permian temnospondyls of South America Permian Brazil Fossils of Brazil Fossil taxa described in 1948