Purussaurus

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Purussaurus
Temporal range:
Ma[1]
Skull restoration of P. brasiliensis
Scientific classification Edit this classification
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. neivensis Mook, 1941
  • †P. mirandai Aguilera et al., 2006
Synonyms

Purussaurus is an

Peruvian Amazon, Colombian Villavieja Formation, Panamanian Culebra Formation, Urumaco and Socorro Formations of northern Venezuela
.

Description

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).

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

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

The probable diet of Purussaurus likely included the extinct turtle

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

References

  1. PMID 34567843
    .
  2. ^
    doi:10.1080/02724634.2007.10010458
    .
  3. ^
    PMID 25689140
    .
  4. S2CID 251560425
    .
  5. ^ Giant extinct caiman breaks constraint on the axial skeleton of extant crocodylians
  6. S2CID 84880200
    .
  7. doi:10.4072/rbp.2006.2.02
    .
  8. S2CID 85950121
    .
  9. ^ Purussaurus at Fossilworks.org

Further reading

  • Rodrigues, J.B. (1892). ""Les reptiles fossils de la Vallée de L'Amazone". Vellosia". Contribuições do Museu Botânico do Amazonas. 2: 41–60.
  • Langston, W (1965). "Fossil crocodilians from Colombia and the Cenozoic history of the Crocodilia in South America". University of California Publications in Geological Sciences. 52: 1–169.

External links

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