Purussaurus

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Purussaurus
Temporal range: Miocene (Friasian-Huayquerian), 16–5.3  Ma [1]
Purussaurus skull.PNG
Skull restoration of P. brasiliensis
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Archosauromorpha
Clade: Archosauriformes
Order: Crocodilia
Family: Alligatoridae
Subfamily: Caimaninae
Clade: Jacarea
Genus: Purussaurus
Rodrigues, 1892
Species
  • P. brasiliensis(type species) Barbosa-Rodrigues, 1892
  • P. neivensisMook, 1941
  • P. mirandaiAguilera et al., 2006
Synonyms

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

Contents

Description

Purussaurus brasilienses Scale.png
Large crocodyliformes.png
Size comparisons of estimates of P. brasiliensis.

The skull length of the largest known individual of the type species, P. brasiliensis is 1,453 millimetres (57.2 in). [2] It has been estimated that P. brasiliensis reached about 10.3 metres (34 ft) in length, weighing about 5.16 metric tons (5.69 short tons). [2] Another estimate gave a larger size of 12.5 metres (41 ft) in length, ranging from 9.9–15.8 metres (32–52 ft), and 8.4 metric tons (9.3 short tons) in weight, ranging from 5.6–12.6 metric tons (6.2–13.9 short tons), with a mean daily food intake of 40.6 kilograms (90 lb). [3] It is also likely that Purussaurus reached only 10.9 metres (36 ft) long and 5.6 metric tons (6.2 short tons). [3] A 2022 study estimated a length of 7.6–9.2 metres (25–30 ft) and a mass of 2–6.2 metric tons (2.2–6.8 short tons) using a phylogenetic approach; and a length of 9.2–10 metres (30–33 ft) and mass of 3.9–4.9 metric tons (4.3–5.4 short tons) using a non-phylogenetic approach. [4] As only skulls have been found, the actual length is not certain. Bite force has been estimated to be around 52,500 N (around 5.3 metric tons-force), with upper estimates indicating that Purussaurus was capable of generating 69,000 N (around 7 metric tons-force). [3] The large size and estimated strength of this animal appears to have allowed it to include a wide range of prey in its diet, making it an apex predator in its ecosystem. As an adult, it would have preyed upon large to very large vertebrates such as the xenarthrans and notoungulates present, with no real competition from sympatric, smaller, carnivores. Researchers have proposed that the large size of Purussaurus, though offering many advantages, may also have led to its vulnerability. The constantly changing environment on a large geological scale may have reduced its long-term survival, favoring smaller species more resilient to ecological shifts. In other words, it was over-specialised and couldn't survive when its habitat changed, unlike smaller related species of caiman. [3]

The skeletal anatomy of P. mirandai shows some adaptations for more upright limb orientation or weight support. Unlike all other members of the crown Crocodylia, which have two sacrals, P. mirandai have three. [5]

The teeth vary between the three species of Purussaurus, but are always around 50 mm (2 in) long and curve slightly backwards. They have small ridges along two of the edges which resemble those in ziphodonts. This indicates that Purussaurus hunted large vertebrates, as these ridges are used for puncturing and holding on to flesh. The teeth are slightly flattened at the top and are roughly conical, which means that they would have been unlikely to break on impact with a thick bone. Teeth at the anterior are taller and more pointed, whereas those at the posterior are lower and more rounded. [3]

Purussaurus is one of the largest known crocodyliformes ever to have existed. Three other extinct crocodyliformes, Sarcosuchus , Deinosuchus , and Rhamphosuchus had similar body sizes. Sarcosuchus and Deinosuchus had similar proportions, but both were geologically much older, dating from the Early and Late Cretaceous, respectively. One study also indicates that Purussaurus may have been heavier than either Sarcosuchus or Deinosuchus, as it had a much broader, shorter snout and this would require a thicker, stronger neck to support the larger head. [3] Rhamphosuchus lived around the same time as Purussaurus, but was slightly smaller, had a more gharial-like snout and lived in India. During the summer of 2005, a Franco-Peruvian expedition (the Fitzcarrald expedition) found new fossils of Purussaurus in the Peruvian Amazon (600 km from Lima).[ citation needed ]

Analysis of a biomechanical model of the skull of Purussaurus indicated that it was capable of performing the "death roll" maneuver used by extant crocodilians to subdue and dismember their prey. [6]

All sense organs (eyes, ears, nostrils) were at the very top of the head, indicating that Purussaurus was an ambush predator like many modern caimans.

Paleoecology

Restoration of Purussaurus brasiliensis Purussaurus BW.jpg
Restoration of Purussaurus brasiliensis

The probable diet of Purussaurus likely included the extinct turtle Stupendemys , crocodilians including Charactosuchus , Gryposuchus , and Mourasuchus , Anhinga birds, and mammals including: sloths, bats, rodents related to the modern capybara ( Josephoartigasia ) weighing up to 700 kilograms (1540 lb), the primate Stirtonia , and river dolphins. Rivers, floodplains, and lake environments were present. [7] Marine and freshwater fish, turtles, crocodilians, and terrestrial and aquatic mammals are associated with Venezuelan P. mirandai. Its environment is described as tropical and coastal. The earlier Colombian P. neivensis lived alongside a massive variety of fauna, including astrapotheres like Granastrapotherium and Xenastrapotherium , the early species of Mourasuchus and Gryposuchus, and the terrestrial crocodyliform Langstonia . This fauna dates from 13 million years ago, in the Laventan stage of the Late Miocene. [8]

Etymology

The genus was named for the Purus River where its fossils were first found.[ citation needed ]

Distribution

Fossils of Purussaurus have been found in: [9]

Miocene

See also

Related Research Articles

<i>Caiman</i> (genus) Genus of reptiles

Caiman is a genus of caimans within the alligatorid subfamily Caimaninae. They inhabit Central and South America. They are relatively small sized crocodilians, with all species reaching lengths of only a couple of meters and weighing 6 to 40 kg on average.

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

Sarcosuchus is an extinct genus of crocodyliform and distant relative of living crocodilians that lived during the Early Cretaceous, from the late Hauterivian to the early Albian, 133 to 112 million years ago of what is now Africa and South America. The genus name comes from the Greek σάρξ (sarx) meaning flesh and σοῦχος (souchus) meaning crocodile. It was one of the largest pseudosuchians, with the largest specimen of S. imperator reaching approximately 9–9.5 metres (29.5–31.2 ft) long and weighing up to 3.45–4.3 metric tons. It is known from two species; S. imperator from the early Albian Elrhaz Formation of Niger, and S. hartti from the Late Hauterivian of northeastern Brazil. Other material is known from Morocco and Tunisia and possibly Libya and Mali.

<i>Deinosuchus</i> Genus of a giant crocodylian

Deinosuchus is an extinct genus of alligatoroid crocodilian, related to modern alligators and caimans, that lived 82 to 73 million years ago (Ma), during the late Cretaceous period. The name translates as "terrible crocodile" and is derived from the Greek deinos (δεινός), "terrible", and soukhos (σοῦχος), "crocodile". The first remains were discovered in North Carolina in the 1850s; the genus was named and described in 1909. Additional fragments were discovered in the 1940s and were later incorporated into an influential, though inaccurate, skull reconstruction at the American Museum of Natural History. Knowledge of Deinosuchus remains incomplete, but better cranial material found in recent years has expanded scientific understanding of this massive predator.

<i>Stupendemys</i> Extinct genus of turtles

Stupendemys is an extinct genus of freshwater side-necked turtle, belonging to the family Podocnemididae. It is the largest freshwater turtle known to have existed, with a carapace over 2 meters long. Its fossils have been found in northern South America, in rocks dating from the Middle Miocene to the very start of the Pliocene, about 13 to 5 million years ago. Male specimens are known to have possessed bony horns growing from the front edges of the shell and the discovery of the fossil of a young adult shows that the carapace of these turtles flattens with age. A fossil skull described in 2021 indicates that Stupendemys was a generalist feeder.

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

Rhamphosuchus is an extinct genus of gavialid crocodylians. It lived during the Pliocene and its fossils have been found in two regions; the Siwalik Hills of Pakistan and India as well as the Sindh region of Pakistan. Its type species is Rhamphosuchus crassidens, which is only known from incomplete sets of fossils, mostly teeth and skulls. Four species traditionally placed in the genus Gavialis may be included as well.

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

Mourasuchus is an extinct genus of giant, aberrant caiman from the Miocene of South America. Its skull has been described as duck-like, being broad, flat, and very elongate, superficially resembling Stomatosuchus from the Late Cretaceous.

<span class="mw-page-title-main">Caiman</span> Subfamily of reptiles

A caiman is an alligatorid belonging to the subfamily Caimaninae, one of two primary lineages within the Alligatoridae family, the other being alligators. Caimans inhabit Mexico and Central and South America from marshes and swamps to mangrove rivers and lakes. They have scaly skin and live a fairly nocturnal existence. They are relatively small-sized crocodilians with an average maximum weight of 6 to 40 kg depending on species, with the exception of the black caiman, which can grow more than 4 m (13 ft) in length and weigh in excess of 1,000 kg. The black caiman is the largest caiman species in the world and is found in the slow-moving rivers and lakes that surround the Amazon basin. The smallest species is the Cuvier's dwarf caiman, which grows to 1.2 to 1.5 m long. There are six different species of caiman found throughout the watery jungle habitats of Central and Southern America. The average length for most of the other caiman species is about 2 to 2.5 m long.

Dinosuchus is a problematic genus of extinct alligatorid crocodilian. It was very large compared to other alligatorids, save for the giant caiman Purussaurus and its closest relatives. The genus was first described in 1876 on the basis of a vertebra from the Brazilian Amazon, the type species being named D. terror. In 1921, a new species of Dinosuchus, D. neivensis, was named based on a large mandible that was discovered in Colombia. D. neivensis was later found to be synonymous with both Brachygnathosuchus braziliensis and Purussaurus brasiliensis, being reassigned in 1924 to the senior synonym P. brasiliensis. In 1965, D. terror was proposed to be a nomen vanum. In 1936, Robert Broom used the name Dinosuchus for a dinocephalian therapsid from South Africa. Broom's Dinosuchus is now considered a junior synonym of Anteosaurus.

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

Gryposuchus is an extinct genus of gavialid crocodilian. Fossils have been found from Argentina, Colombia, Venezuela, Brazil and the Peruvian Amazon. The genus existed during the Miocene epoch. One recently described species, G. croizati, grew to an estimated length of 10 metres (33 ft). Gryposuchus is the type genus of the subfamily Gryposuchinae, although a 2018 study indicates that Gryposuchinae and Gryposuchus might be paraphyletic and rather an evolutionary grade towards the gharial.

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.

<span class="mw-page-title-main">Stomatosuchidae</span> Extinct family of reptiles

Stomatosuchidae is an extinct family of neosuchian crocodylomorphs. It is defined as the most inclusive clade containing Stomatosuchus inermis but not Notosuchus terrestris, Simosuchus clarki, Araripesuchus gomesii, Baurusuchus pachecoi, Peirosaurus torminni, or Crocodylus niloticus. Two genera are known to belong to Stomatosuchidae: Stomatosuchus, the type genus, and Laganosuchus. Fossils have been found from Egypt, Morocco, and Niger. Both lived during the Cenomanian stage of the Late Cretaceous. The skulls of stomatosuchids are said to be platyrostral because they have unusually flattened, elongate, duck-shaped craniums with U-shaped jaws. This platyrostral condition is similar to what is seen in the "nettosuchid" Mourasuchus, which is not closely related to stomatosuchids as it is a more derived alligatoroid that existed during the Miocene.

<span class="mw-page-title-main">Castillo Formation, Venezuela</span>

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.

Culebrasuchus is an extinct, monotypic genus of caiman alligatorid known from the Early to Middle Miocene (Hemingfordian) of the Panama Canal Zone of Panama. It contains a single species, Culebrasuchus mesoamericanus.

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.

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

Gnatusuchus is an extinct genus of caiman represented by the type species Gnatusuchus pebasensis from the Middle Miocene Pebas Formation of Peru. Gnatusuchus lived about 13 million years ago (Ma) in a large wetland system called the Pebas mega-wetlands that covered over one million square kilometers of what is now the Amazon Basin.

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 that lived during the Late Miocene, around 11.6 million years ago, to the end of the Miocene 5.3 million years ago in Acre and Amazonas, Brazil as well as Urumaco, Venezuela. Several specimens have been referred to the species, but only 3 of them are confidently placed in the species. C. brevirostris was originally named in 1987 on the basis of a single, incomplete rostrum with an associated mandibular ramus that had been found in Acre, Brazil. C. brevirostris is very distinct among Caiman species and caimaninae overall in that it preserves a characteristically short and robust skull that bears blunt posterior teeth that were built to break down harder foods. This was an adaption for durophagy, likely to crush shells of mollusks and clams which were common in the wetlands that C. brevirostris resided in.

Acresuchus is an extinct monospecific genus of medium-sized caiman from the Late Miocene of western Brazil and Venezuela. The genus contains a single species, Acresuchus pachytemporalis. Acresuchus is a close relative of the giant caiman Purussaurus.

<i>Pseudoprepotherium</i> Extinct genus of ground sloths

Pseudoprepotherium is an extinct genus of sloths of the family Mylodontidae. It was widespread across northern South America during the Early to Late Miocene epoch around 21 to 5.3 million years ago. Fossils of the animal have been found in Brazil, Venezuela, and Peru. Pseudoprepotherium lived in a tropical climate with a water-rich environment. Their known remains are limited to limb bones, except for a few skulls and teeth. Based on these remains, they were most likely medium to large-sized mylodontid. The genus was described in 1961 and currently contains three species, which were originally assigned to the genus Prepotherium.

References

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  5. Giant extinct caiman breaks constraint on the axial skeleton of extant crocodylians
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  9. Purussaurus at Fossilworks.org

Further reading