Creature Feature #9: Purussaurus Spp.

A cast of the skull of Purussaurus brasiliensis. Image courtesy of Carnoferox

Scientific Classification

Kingdom: Animalia

Phylum: Chordata

Class: Reptilia

Order: Crocodylia

Family: Alligatoridae

Subfamily: Caimaninae

Genus:Purussaurus (Barbosa-Rodrigues, 1892)

Species: P. brasiliensis (type) (Barbosa-Rodrigues, 1892), P. neivensis (Mook, 1941), P. mirandai (Aguilera et al. 2006)

Synonyms: Dinosuchus terror (Gervais, 1876), Brachygnathosuchus braziliensis (Mook, 1921), Dinosuchus neivensis (Mook, 1941), Caiman neivensis (Langston, 1965)

Distribution: Solimões Formation, Brazil (P. brasiliensis), Cobija Formation, Bolivia (P. brasiliensis), Villavieja Formation, Colombia (P. neivensis), Pebas Formation, Peru (P. neivensis), Urumaco Formation, Venezuela (P. mirandai), Ipururo Formation, Peru (P. sp.), Culebra Formation, Panama (P. sp.)

Time Period: Colhuehuapian-Huayquerian Stages (SALMA) of the Late Miocene (ca 19 - 6 Ma)

Size: 12.5 meters (41 feet), 7.6 tonnes (8.4 tons)

Restoration of P. brasiliensis. Image courtesy of Wikipedia

Discovery and Naming:

João Barbosa Rodrigues discovered a giant skull of a long dead crocodilian in the Amazon in 1892 and he named it Purussaurus brasiliensis. The name derives from the country Brazil and the Purus River. Since then, there have been two more species that have been named, P. neivensis in 1941 and P. mirandai in 2006. An earlier and possibly ancestral species is known from Panama, but it has yet to be named.

A depiction of the skull of Purussaurus. Image courtesy of Wikimedia Commons

Bite Force and Death Roll:

From just a glance at the massive and thick skull of Purussaurus, one can already see that this creature must have had a massively powerful bite. Another prehistoric monster known for its massive bite is Tyrannosaurus rex. At around 12.5 meters long, it was about the same length as Purussaurus. In 2015, it was estimated that this massive crocodilian could bite down with a force of approximately 69,000 newtons (~15,500 pounds or 7.75 tons). Tyrannosaurus rex could only generate ~35,586 netwons (8000 pounds or 4 tons) of force. It is also suggested that Purussaurus had strong enough bones to perform a “death roll.” A death roll is when a crocodilian grabs a limb or the body of a prey animal and then twists and turns in a spiraling motion, ripping huge chunks of flesh off into pieces that the feasting crocodilian can swallow whole.

The giant turtle Stupendemys geographicus. Image courtesy of Wikipedia

Diet:

The species of Purussaurus had different prey options depending on the formation they were from. The Brazilian species, P. brasiliensis, likely preyed upon the Stupendemys, a giant turtle with an estimated to have been between 2.4-3.3 meters (7.9-11 feet) long as well as a wide selection of sharks, rays, primates, sloths, and birds. Judging by the size and shape of the skull of Purussaurus as well as its massive bite force, it is safe to assume that it used its jaws to crack open and crush the shells of giant turtles such as Stupendemys. Telicomys gigantissimus, a giant rodent that measured 2 meters (6.6 feet), would have been a viable source would have been a viable option for P. brasiliensis. It is likely that juvenile Purussaurus would have fed on the variety of semi-aquatic birds, primates, and sloths that ventured too close to the water’s edge. It is likely the prey would not have seem the attack coming, the crocodilian’s massive jaws would either immediately kill the prey on the initial bite or, if it was tougher, be held underwater until it drowned.

Sketch of Gryposuchus. Image courtesy of Wikipedia

Contemporary Fauna:

The giant gharial, Gryposuchus, lived alongside the different species of Purussaurus. G. neogaeus lived with P. brasiliensis in Brazil, G. colombianus lived with P. nievensis in Colombia, and G. croizati with P. mirandai in Venezuela. The largest species, Gryposuchus croizati, was estimated to have been able to grow up to 10.15 meters (33.3 feet) in length, which puts it at about the same size to slightly smaller than Purussaurus in length. In weight, Purussaurus was thought to have weighed between 5,200-8,400 kilograms (5.7-9.2 tons) while Gryposuchus only tipped the scales at 1,745 kg (1.92 tons) according to Riff and Aguilera (2008). While they may have been similar in size, it is likely that the two giant crocodilians would likely have occupied different niches in the environments they inhabited. Gryposuchus, being a gharial whose skull and jaws were very long and thin, would not have had the ability to hunt the giant turtles or large mammals that inhabited its environments so it likely preyed upon the sharks, rays, and other fish due to its needle like teeth being perfect for gripping slippery fish. Purussaurus, on the other hand, likely would stuck to hunting the mammals and turtles as well as any smaller crocodilians, such as juveniles of its own species as well as from Gryposuchus. Its robust skull and limbs would have been backed by powerful muscles, allowing this monster caiman to drag any prey it pleased down to a watery grave. Another large crocodilian that inhabited the Amazon during the Miocene, the 12 meter (39.4 foot) long Mourasuchus spp., whose weak looking jaw and small teeth for a crocodilian its size may have indicated it as feeding on smaller fish and other aquatic creatures, which there was a great number of in the Miocene Amazon.

Paleosuchus palpebrosus (Cuvier’s Dwarf Caiman). Image courtesy of Wikipedia

Closest Living Relatives:

Purussaurus belonged to the subfamily Caimanae, which the largest of today is Melanosuchus **** (Black Caiman). It measures up to 5 meters (16.7 feet) in length and tips the scale at up to 1100 kilograms (1.21 tons). One would think that this would be the closest living relative to the largest caiman ever known, but this is actually false. The closest living relative of behemoth Purussaurus is in fact, the genus Paleosuchus spp. This genus contains two species: P. trigonatus and P. palpebrosus. The latter is known as Cuvier’s Dwarf Caiman, the smallest crocodilian alive today at a mere 1.2-1.4 meters (3.9-4.6 feet) in length and 6-7 kilograms in weight. The dwarf caiman would have been the same length as the skull of Purussaurus. Quite ironic that the closest we have related to such an impressive beast such as Purussaurus weighs the about same as a small child. The dwarf caiman is around 1/10 of the length and 1/1400 of the weight of the giant which was Purussaurus.

In Popular Culture:

Purussaurus has not had much attention when it comes to popular culture, which is unfortunate. The only known appearance is in a single episode of the series Paleoworld called “Ancient Crocodiles.” The episode aired in 1996 and was the first episode of Season 3. The documentary exaggerates the size of the beast, claiming it was 15.25 meters (50 feet) long and weighed 16.3 tonnes (18 tons). This is obviously not the case.

Extinction:

The fossils of Purussaurus disappear at around 6 Ma during the Late Miocene. Likely what caused this giant to become extinct is the same as any giant predator: loss of food. The species which it depended upon for food disappeared. Needing around 40 kilograms of food a day, Purussaurus would have suffered the adverse effect of gigantism: starvation. It grew huge to dominate its environment and kill the large prey it ate and when those prey animals disappeared, so did Purussaurus.

Conclusion:

Purussaurus has to be my favorite of all of the giant crocodilians of the prehistoric world. It dominated its world and grew to the same size and even larger than some of the dinosaur killers of the Mesozoic. It rivaled both Deinosuchus riograndensis (10.6 meters) and Sarcosuchus imperator (11-12 meters), two genera well-known for being some of the largest crocodilians to have ever existed, in size and easily exceeded both of them in jaw strength. Quite simply, Purussaurus was a monster among monsters. It is somewhat terrifying to think there was a beast lurking the water’s edge only 6 million years ago and that if the planet’s climate warms up again, the return of giants such as this one might not be out of the question.

References:

So... what do you think? Please leave me a comment.

5 Comments:

  • Vale: Great Creature Feature! I never heard of these until now :) Why might they have only existed in Central / South America?
  • Torvosaurus i.: I think it was confined to that region due to that area being the only that seemed to have the ideal conditions for a crocodilian its size to develop. Plus, that is the region the Caimanae are confined to in modern times.
  • Vale: That makes sense :)
  • Carnoferox:

    At the time the northern part of South America would’ve been a massive series of wetlands (like a giant Everglades), ideal habitat for crocodilians.

  • Vale: Thanks for the answer Carnoferox

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