Purussaurus

Credit: Megaraptor-The-Allo on the Wikimedia Commons.

*Purussaurus* is an extinct genus of caiman that lived in South America from the Early to Late Miocene.

## Description

*Purussaurus* is known from many remains from a list of Miocene formations. In form, *Purussaurus* most looked like an alligator, with a blunt and boxy skull. *Purussaurus* is actually a type of caiman; sitting in Caimaninae, which sits in Alligatoridae. *Purussaurus* had a skull which was about 1453 millimeters, in the largest species, *P. brasiliensis*. The largest estimates for *Purussaurus* is about 15.8 meters (52 feet) long and weighed about 12.6 metric tons (13.8 short tons). This size estimate is often met with scrutiny, and it is more plausible that *Purussaurus* was about 9-11.2 meters (29-36 feet) long and 5.6 metric tons (6.2 short tons) in weight. It is very difficult to determine a definitive size due to most estimates scaling the skull to the rest of the body. Most cases estimate the bite force of *Purussaurus* was about 52,500 Newtons (about 5.3 metric tons). This factor and the animals massive size makes *Purussaurus*' diet quite broad, thus making *Purussaurus* an apex predator.

The teeth of *Purussaurus* vary between species, but are usually about 50 millimeters (2 inches) long and were slightly recurved. The individual teeth had small ridges along two of the tooth's edges. This indicates that the animal ate large vertebrates, as these types of teeth are specialized for puncturing and holding mounds of flesh. The teeth are also slightly flattened at their peaks, and conical, which makes tooth breakage unlikely when a bone is struck. The teeth located at the anterior end of the mouth are taller and more pointed, which the ones at the posterior end are shorter and blunter. *Purussaurus* is among the largest crocodyliformes known to have existed, being larger than both Sarcosuchus and Rhamphosuchus who are 9 meters and 8-11 meters respectively. The first two have similar proportions, but are geologically older. However, recent estimates suggest that Deinosuchus and Astorgosuchus could be even larger, with Deinosuchus reaching over 13 meters and weigh 12 tons with the latter reaching 10-12 meters and weighing 8-10 tons Rhamphosuchus lived alongside the same time as *Purussaurus*, was similar in size, but appeared more gharial-like. Biomechanical studies of *Purussaurus*' skull show it utilized the classic crocodilian death roll. The death roll is used by crocodilians to stun, subdue, and dismember their prey. It is performed by clamping tightly onto prey, and spinning quickly in the water. All organs used for sense (eyes, ears, nostrils...) are located on the top of its head, indicating that *Purussaurus* was an ambush predator. Upper estimates for it's bite are 69,000 Newtons (7 metric tons). If these are to be trusted, it would have been one of the greatest bite forces ever, only outmatched by Megalodon.

## Species

* *P. brasiliensis*
* *P. neivensis*
* *P. mirandai*

## Paleoecology

### Extinction

Adult *Purussaurus* would have preyed on massive animals that lived by the waters side, or were just coming for a drink. Adults would have had little competition with small carnivores. This makes scientist propose that while a large size poses many advantages, one disadvantage is vulnerability in terms of changing climate and environmental changes. This ultimately caused *Purussaurus* to fall extinct due to it not being to adapt like small caimans can.

### Paleoenvironment

*Purussaurus* lived in the Villavieja, Culebra, Urumaco, Pebas, Solimões, Ituzaingó, Castilletes and Socorro Formations. It lived in bodies of water, sharing its habitat with a wide array of animals. Water was inhabited by the turtle *Stupendemys*, the crocodilians *Charactosuchus*, *Gryposuchus*, *Mourasuchus*, river dolphins and the extant bird genus Anhinga. The land was shared by many mammals; bats, ground sloths, rodents and massive relatives of the capybara. The ape *Stirtonia* and several ungulates also populated the same areas *Purussaurus* did. *Purussaurus* preferred coastal, tropical landscapes from the Early to the Late Miocene, where *Purussaurus* went extinct. The partial tooth MAS-PV 386 from Toma Vieja, Argentina was described in 2023 and allocated to the genus, but not a specific species. This extends the range of this genus to the Argentinian lower Ituzaingó Formation of Late Miocene strata.

## References

1. ↑ 1.0 1.1 1.2 https://en.wikipedia.org/wiki/Purussaurus
2. ↑ 2.0 2.1 http://revista.macn.gob.ar/ojs/index.php/RevMus/article/view/797