An Ultimate Guide to Purussaurus: The Purus River Lizard

Leave a comment / / Updated on: 24th September 2023

Name Meaning“The Purus River Lizard”HeightN/A
PronunciationPu-ruh-sore-usLength9 to 12 meters (29.5 to 39.4 feet)
EraMesozoicLate CretaceousWeight5 to 12 metric tons (5.5 to 13.2 short tons)
ClassificationReptilia,‭ Crocodilia & AlligatoridaeLocationSouth America

Purussaurus Pictures

3D illustration of Purussaurus
3D illustration of Purussaurus | Disneysaurus via Dinosaur Wiki

The Purussaurus

Gage Beasley Prehistoric's Purussaurus Concept
Gage Beasley Prehistoric’s Purussaurus Concept

Imagine the saltwater crocodile, the largest living reptile.

Now, imagine a reptile much larger than the saltwater crocodile!

That’s Purussaurus, the Purus River lizard!

This giant caiman lived in South America roughly 16-5.3 million years ago, and some call it the world’s largest and heaviest crocodylomorph.

However, this statement is debatable, as scientists aren’t fully certain about their maximum size.

It’s also important to know that the genus consists of three species: P. brasiliensis, P. neivensis, and P. mirandai.

Without further introduction, let’s learn about some jaw-dropping details of Purussaurus!

Gage Beasley's Prehistoric Shirt Collection
Gage Beasley’s Prehistoric Shirt Collection
Gage Beasley's Prehistoric Plush Collection
Gage Beasley’s Prehistoric Plush Collection

Physical Characteristics

Gage Beasley Prehistoric's Purussaurus Size Comparison Chart
Gage Beasley Prehistoric’s Purussaurus Size Comparison Chart

All extant crocodiles have a similar body plan, including the skeleton, adapted to an aquatic lifestyle.

Most extinct crocodilians had a similar body plan, meaning they had nine neck vertebrae, 15 trunk vertebrae, and two pelvic vertebrae.

However, this body plan is not valid for Purussaurus, as they’re structured differently, which makes them unique!

Studies on a Purussaurus mirandai specimen revealed one less vertebra in the trunk and an extra one in the pelvic area.

As such, unlike all crocodilians, P. mirandai had 14 trunk vertebrae and three pelvic vertebrae.

This arrangement aided in supporting the massive body weight and avoiding any damage to the skeleton.

It also indicates that other extinct crocodilians may have similar skeleton structures.

Another distinctive characteristic of the genus Purussaurus is the huge external naris (nostril) that occupies almost half of the rostrum.

Moreover, since it had a larger head than most other creatures, it likely also had a thicker, stronger neck that could support the weight of the unusually large head. 

Photo of skull fossil of Purussaurus
Photo of skull fossil of Purussaurus | AllosaurusRex95 via Dinopedia

Unfortunately, since the members of this extinct caiman genus are known primarily from fossilized skulls, very little is known about their postcranial skeleton and overall appearance, except that they had a typical crocodilian body plan.

It has also been concluded that they had a slightly upright limb orientation.

The size of these caimans is highly debated, as length and weight estimations are based primarily on skull lengths.

The largest skull belongs to the type species, Purussaurus brasiliensis, measuring 1.45 meters (57.2 inches), indicating that that specimen was roughly 10.3 meters (33.8 feet) long and weighed 5.16 metric tons (5.69 short tons).

However, other specialists suggest a different overall size for these creatures – an average of 12.5 meters (41 feet) in length, although the range could be between 9.9 and 15.8 meters (32.4 to 51.9 feet).

Various weight estimations have also been proposed, ranging from 5.6 to 12.6 metric tons (6.2-13.9 short tons).

If you think that’s the end of estimations, we’ll disappoint you!

Another recent study concluded that Purussaurus specimens might have been smaller and lighter, measuring 7.6-9.2 meters (25-30.2 feet) long and weighing 2-6.2 metric tons (2.2-6.8 short tons).

While the actual size has yet to be finalized, the general consensus is that Purussaurus is one large Alligatoridae
While the actual size has yet to be finalized, the general consensus is that Purussaurus is one large Alligatoridae | Nobu Tamura via Wikipedia CC BY 3.0

Long story short, no one knows for sure how long and heavy these creatures were, but to the human eye, it doesn’t matter if they measured 7 or 12 meters – they were still giants.

Purussaurus also had some interesting facts about their teeth!

The three species had slightly different teeth, but all measured roughly 5.5 cm (2.2 inches) long!

They also featured small ridges on the edges, indicating the type of prey the caimans preferred.

Since the teeth were typically conical and slightly flattened at the top, they were resistant to bone contact.

Habitat and Distribution

Purussaurus fossils were recovered from the following locations:

  • Brazil’s Solimões Formation
  • Colombia’s Honda Group and Castilletes Formation
  • Peru’s Fitzcarrald Arch and Pebas Formation
  • Panama’s Culebra Formation
  • Venezuela’s Urumaco and Socorro Formation.

Considering the wide distribution of their fossils, it is quite challenging to outline a preferred habitat for Purussaurus.

However, they’re typically considered creatures of tropical and coastal areas.

Studies show that the Honda Group has been deposited in a fluvial environment with precipitation levels of approximately 1,500-2,000 millimeters.

Based on the type of vegetation the ecosystem supported, scientists compare the habitat with those of Africa and Asia.

The Castilletes Formation had a strong fluvial influence, while the Pebas Formation is known to represent the deposits of a series of lakes.

Venezuela’s Urumaco Formation was a highly aquatic environment, featuring large rivers, estuaries, and lagoons. Shallow coastal seas were also present.

Panama’s Culebra Formation is believed to have featured a combination between marine and volcanic deposits.

Behavior and Diet

The Purussaurus was an aquatic predator, and while some extinct crocodilians weren’t physically adapted for the death-roll maneuver to subdue prey, the Purussaurus was likely very good at it.

Purussaurus employed ambush tactics to subdue its prey
Purussaurus employed ambush tactics to subdue its prey | Dinoknight via Animal of the world Wiki

Moreover, since its sense organs were at the top of its head, it primarily relied on ambush techniques, similar to modern caimans.

Some studies calculated the bite force of a Purussaurus brasiliensis specimen that measured 12.5 meters (41 feet) long and weighed 8,424 kilograms (18,571 pounds).

The results showed a bite force of 69,039.2 N, which is about twice the bite force of the T-Rex!

Obviously, these are only estimations, but they still provide an overall idea of how strong these creatures were.

Moving further, Purussaurus caimans had a daily food intake of roughly 21.6-59.5 kilograms (47.6-131.2 pounds).

However, this does not necessarily mean they ingested this amount everyday, as it is well-known that crocodilians do not require frequent meals.

Considering the strong bite force and the fact that it is among the world’s largest and heaviest crocodylomorphs, scientists argue that the Purussaurus was an apex predator in its habitat and could subdue any prey it went for.

It has also been suggested that Purussaurus had a diet similar to that of extant caimans.

A Purussaurus trying to catch a bird
A Purussaurus trying to catch a bird | Image via SurviveTheArk

This means that juveniles likely ate insects, fish, and mollusks.

Once they became fully mature, they switched to a diet that would also include birds, mammals, turtles, and snakes.

Since Purussaurus had a large head and a short and broad snout, they likely preyed on very large reptiles and terrestrial mammals, which are out of the reach of modern caimans.

Even if we compare the Purussaurus with one of the world’s largest crocodilians, the Nile crocodile, we’ll get similar results.

While the Nile crocodile can subdue and feed on animals of up to 900 kilograms (1,984 pounds), the Purussaurus was able to capture prey weighing more than 1 ton (1.1 short tons)!

Some scientists suggest that Purussaurus might have eaten fruits as well!

Another important thing to note is that these creatures might have engaged in aestivation, a type of animal dormancy.

Modern caimans are known to dig a burrow and spend some time hibernating, which may have also applied to extinct caiman species.

Purussaurus may have dug burrows near its hunting grounds
Purussaurus may have dug burrows near its hunting grounds | Scanova via Additional Creatures Wiki

Life Cycle

To understand the reproductive process and the life cycle of Purussaurus, we must turn to what we know about crocodilians.

Probably not all characteristics and behaviors apply fully to Purussaurus since they lived millions of years ago, and certain things may have changed over time, but we can at least outline a possible picture regarding this aspect.

First, male crocodilians are known to mate with as many females as possible, and monogamous pairings are pretty rare.

Moreover, some crocodilians are known to reproduce through parthenogenesis, a form of asexual reproduction.

However, this has been observed only in American crocodiles.

Some males engage in courtship displays, during which they rub against females, circle them, and display swimming courtship patterns.

When the female arches her back and submerges her head and tail, she’s ready to mate.

Then, the male grasps her with the hindlimbs and aligns in a way that makes penis insertion possible.

Purussaurus had a mating ritual similar to its modern day counterpart
Purussaurus had a mating ritual similar to its modern-day counterpart | Scanova via Additional Creatures Wiki

During mating, the pair submerge and surface repeatedly.

About one month after mating, females build nests, typically holes or mounds consisting of litter, sand, and vegetation.

After this, they lay between 10-50 eggs in a single clutch, and these eggs require an incubation period of 2-3 months.

The temperature they’re incubated at directly impacts the sex of the hatchlings.

All offspring typically hatch simultaneously, upon which their mother carries them to the water.

The father and the mother typically remain close to their babies.

However, this is not valid for all species, as some rely on something called nurseries, meaning that the offspring are cared for by a group of crocodilians, not only their parents.

Either way, it may take between two months and two years (depending on the species) for the offspring to become independent.

Evolution and History

Size comparisons of P. brasiliensis
Size comparisons of P. brasiliensis. | Smokeybjb et al. via Wikipedia CC BY-SA 3.0

Purussaurus is part of the Crocodylomorpha clade and, as such, its oldest known ancestors inhabited Earth since the Late Triassic.

The earliest crocodylophorms were sphenosuchians – small, gracile animals.

These creatures were the only pseudosuchians that survived the Triassic-Jurassic extinction event.

During the Early Jurassic, many ecological niches remained vacant upon the extinction of other animals, and these crocodylomorphs had to undergo numerous changes and adaptations to fill those niches.

During the Jurassic and the Cretaceous, many evolved paddle-like forelimbs and fish-like tails adapted for an aquatic lifestyle.

The Eusuchia clade, which includes the Purussaurus and all extant crocodilians, appeared roughly 80 million years ago.

The oldest known member of the Eusuchia clade is the Hylaeochampsa vectiana, followed by the hoofed crocodiles of the Paleogene.

Purussaurus is now part of the Jacarea clade, alongside the extant genera Caiman and Melanosuchus.

Size comparisons of P. brasiliensis.
Size comparisons of P. brasiliensis. | Megaraptor-The-Allo via Wikipedia CC0

In 1988, the Jacarea clade had been cladistically defined as being the last common ancestor of the following extinct species:

  • Broad-snouted caiman
  • Spectacled caiman
  • Yacare caiman
  • Black caiman

Interactions with Other Species

It goes without saying that the Purussaurus lived alongside a myriad of other prehistoric creatures.

Considering its wide range, listing all creatures that the Purussaurus crossed paths with would be impossible.

However, here’s a comprehensive list of some types of animals that roamed South America during the same period:

  • Turtles like Stupendemys
  • Crocodilians like Mourasuchus and Gryposuchus
  • Birds like Anhinga
  • Mammals like bats, sloths, and rodents
  • New World monkeys like Stirtonia
  • River dolphins
  • Freshwater fish
  • Astrapotheres (hoofed mammals) like Xenastrapotherium and Granastrapotherium
  • Crocodyliforms like Langstonia
Purussaurus biting down upon a Stupendemys
Purussaurus biting down upon a Stupendemys | Clumsystiggy via Prehistoric Wiki

Studies show that since the Purussaurus was an apex predator, its extinction likely caused a large-scale ecosystem regime shift.

This, in turn, resulted in secondary extinctions and a complete reshaping of the habitat.

Cultural Significance

Considering its role and location in the crocodilian and caiman lineage, it’s no wonder the Purussaurus has aroused the interest of so many scientists.

Thanks to their studies, we now have a more complete picture of our world’s evolutionary history.

All that’s left today is to hope for future paleontological discoveries that will reveal more fascinating details about this creature’s postcranial skeleton, which remains poorly studied.

If you want to see a reconstruction of the Purussaurus, check out the Paleoworld documentary series or play the Jurassic World Alive mobile game.

Purussaurus as seen in Jurassic World: Alive mobile game
Purussaurus as seen in Jurassic World: Alive mobile game | Animalman57 via Jurassic Park Wiki

However, don’t forget that these representations may be slightly erroneous!


Are you now convinced that, despite not being as popular as other prehistoric creatures, the Purussaurus was just as or even more fascinating?

The Purussaurus was an apex predator in its habitat, and no vertebrate was outside its reach.

Its size wasn’t the only thing that made it unique – it also had a different vertebrae arrangement and an unusually large external nostril!

Unfortunately, this fascinating caiman went extinct about 5 million years ago, and its large size might have contributed to its extinction.

It was less resilient than smaller species to the constant environmental changes.


Is Purussaurus the biggest crocodile?

Since the maximum size of the Purussaurus hasn’t been fully confirmed yet, it is unknown whether it was indeed the largest.

However, it is definitely among the top, alongside Sarcosuchus, Reinosuchus, and Rhamphosuchus.

Is Purussaurus stronger than T-Rex?

Since they’re different creatures with different lifestyles and hunting adaptations, it would be challenging to state which one was stronger.

If we compare their bite forces, however, we must admit that the bite force of the Purussaurus was much stronger than that of the T-Rex.


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