An Ultimate Guide to Deinosuchus: The Terrible Crocodile

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Name MeaningTerrible crocodileHeight3.9 feet (1.2 meters)
PronunciationDyi-noh-sook-usLength26.2-49.2 feet (8-15 meters) 
EraMesozoicLate CretaceousWeight5,000-17,000 lbs (2,268-7,711 kg)
ClassificationReptilia, Crocodilia & AlligatoroideaLocationNorth America

Deinosuchus Pictures

Illustration of Deinosuchus in a white background
Illustration of Deinosuchus in a white background | Andrey Atuchin via Wikipedia CC BY-SA 4.0

The Deinosuchus

Gage Beasley Prehistoric's Deinosuchus Concept
Gage Beasley Prehistoric’s Deinosuchus Concept

The Deinosuchus, often called the world’s largest crocodyliform, played an important role in shaping our world’s Late Cretaceous period, as it was likely an apex predator in its habitat.

Also known as the terrible crocodile, the Deinosuchus was widespread across North America. 

Its fossils were unearthed from at least ten U.S. states and possibly from Mexico.

The Deinosuchus was remarkably large, covered in thick osteoderms, and probably relied on an ambushing technique to catch prey. 

While it primarily fed on turtles and fish, the Deinosuchus occasionally ventured on the ground to catch some terrestrial animals, including dinosaurs.

In this article, we’ll share some fascinating details about the Deinosuchus. No prehistoric wildlife enthusiast wants to miss them, so keep reading!

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 Deinosuchus Size Comparison Chart
Gage Beasley Prehistoric’s Deinosuchus Size Comparison Chart

The Deinosuchus was remarkably similar to modern crocodiles in terms of physical characteristics, except that it was larger.

Although it is widely recognized that the Deinosuchus was indeed a very large alligatorid, exact numbers remain debatable, as they are calculated based on fragmentary fossils.

In 1954, it was estimated that the Deinosuchus measured 15 meters (49.2 feet) long, a result based on a 1.5-meter (4.9-foot) skull. 

In 1999, however, scientists proposed a different result – 8 to 10 meters (26.2-33 feet) in length.

The weight was initially estimated at 2.5-5 metric tons (2.8-5.5 short tons), but other scientists suggested a weight of up to 8.5 metric tons (9.4 short tons) – quite a difference, don’t you agree?

Without further research, one would say the Deinosuchus was the world’s largest crocodyliform. 

3D illustration of Deinosuchus in a white background
3D illustration of Deinosuchus in a white background | Sphenaphinae via Wikipedia CC BY-SA 4.0

However, not even scientists are sure yet whether this is true. 

Some argue that the Purussaurus was just as large or even larger.

Unfortunately, as with anything related to paleontology and our world’s prehistory, the sizes for both genera are only estimations, and we’ll never know the whole truth.

Apart from its unusually large size, the Deinosuchus is most renowned for the odd shape of its skull – it was broad, inflated at the front, and featured two holes in the premaxilla. 

This shape makes the Deinosuchus unique among creatures of its kind.

Its teeth were thick and robust but varied in size and shape depending on their location on the maxilla. 

Deinosuchus is an extinct species of crocodylian that lived during the Late Cretaceous period
Deinosuchus is an extinct species of crocodylian that lived during the Late Cretaceous period | BeyonderGodOmnipotent via the isle wiki fandom

For example, those closer to the rear jaw were shorter and rounded and weren’t used for piercing, like the other teeth.

The Deinosuchus had its back covered in large, deeply pitted osteoderms. 

Habitat and Distribution

The Deinosuchus lived approximately 82-73 million years ago. 

Fossils belonging to this large alligatorid were discovered in at least ten U.S. states and possibly northern Mexico.

Texas and Montana were among the richest locations, but fossils have also been found in many East Coast localities. 

As such, the Deinosuchus was widespread on both parts of the Western Interior Seaway.

Fossil discovered by Barnum Brown
Fossil discovered by Barnum Brown | Barnum Brown via Wikimedia Commons

Here are the localities that revealed Deinosuchus fossils:

  • Texas
  • Willow Creek, Montana
  • Wyoming
  • Utah
  • New Mexico
  • Georgia
  • Alabama
  • Mississippi
  • Bladen County, North Carolina
  • New Jersey

Some fossils from Colorado, Delaware, South Carolina, and northern Mexico were attributed to the genus but never officially recognized, so the distribution of Deinosuchus across these locations remains just speculation.

The location that turned out to be most abundant in Deinosuchus fossils was the Gulf Coastal Plain in Georgia, while the largest individuals belong to the Aguja Formation in Texas.

Since it would be challenging to focus on all localities where Deinosuchus fossils were recovered, we’ll describe the Aduja Formation.

This territory is thought to have consisted of marine, paralic, and inland floodplain environments. 

Fossil specimen of deinosuchus
Fossil specimen of deinosuchus | Daderot via Wikimedia Commons CC0

The Deinosuchus fossils were discovered in the lower part of the upper Aguja Formation, which was likely a fluvial environment with coastal and inland floodplains.

Some sources list that the Deinosuchus was particularly fond of brackish-water bays, meaning habitats with natural water higher in salinity than freshwater. 

They may have also ventured into marine environments but probably didn’t visit the ocean.

Behavior and Diet

The Deinosuchus is thought to have had a relatively strict aquatic lifestyle. 

However, it probably ventured on the ground, too, especially since it is thought to have been a dinosaur predator. 

Considering that its maximum bite force was probably at least 18,000 N and at most 102,803 N, this isn’t surprising!

Deinosuchus was one of the largest crocodyliformes that ever lived
Deinosuchus was one of the largest crocodyliformes that ever lived | Arvalis via VS battles fandom

Additionally, scientists consider this plausible because they haven’t found another explanation for the large size of this crocodile.

As such, it may have fed occasionally on ornithopods and other terrestrial animals walking leisurely near the water’s edge.

Supposedly, the Deinosuchus ambushed its prey and dragged it underwater to drown it. Quite clever, don’t you agree?

While other prehistoric crocodyliforms like the Sarcosuchus couldn’t perform the famous death roll used to subdue and dismember large prey, the Deinosuchus and its large relative, the Purussaurus, were likely well-equipped physically to perform this trick.

This further supports the theory that Deinosuchus may have fed on larger terrestrial animals, including small and large dinosaurs.

Besides dinosaurs and other terrestrial creatures, the Deinosuchus largely preyed on marine turtles, especially the Bothremys side-neck turtle and large fish.

Life Cycle

Deinosuchus in a swamp looking for prey
Deinosuchus in a swamp looking for prey | Moondirts via the isle wiki

To understand the reproductive behavior of the Deinosuchus, we must turn to what is known about the reproductive behavior of crocodilians in general. 

Since few studies focus on this particular genus and this particular topic, very little is known about its specific behavior. 

However, we can assume that the behavior was similar to that observed in modern crocodilians.

As such, we’d like to point out that crocodilians reproduce sexually, like other reptiles, and mating occurs through the cloaca, which is located at the base of the tail of the female reptile. 

At the same time, the male possesses a single median penis which, after mating, is retracted within the body.

These creatures are believed to be polygynous, which means that males mate with as many females as possible. 

Only American alligators are monogamous pairings, while American crocodiles reproduce asexually.

Deinosuchus is gliding through marshy waters
Deinosuchus is gliding through marshy waters | LuqBot via the isle wiki

Since there are exceptions to this polygynous behavior, we cannot rule out the possibility that the Deinosuchus may have been monogamous or parthenogenous.

As with modern birds and probably prehistoric dinosaurs, crocodiles participate in courtship displays, and mating occurs in the water. 

One month later, females start building nests, typically holes or mounds near caves or dens. 

The same female may build several nests placed close to each other.

The eggs were laid in clutches, and the incubation lasted approximately 2-3 months. 

It is worth noting that crocodilians are among those creatures whose sex is determined by the temperatures at which incubation occurs.

The snout of this predator was broad and bulky, equipped with large conical teeth meant for crushing
The snout of this predator was broad and bulky, equipped with large conical teeth meant for crushing |  LuqBot via the isle wiki

Once the babies hatch, both parents show remarkable parental care by carrying their young to water, responding to vocalizations, and helping them feed.

We must stress that things may have been slightly different millions of years ago, but we still consider these details quite comprehensive in understanding the possible Deinosuchus reproductive behavior.

It has been suggested that the Deinosuchus had a lifespan of 50-51 years. 

It is believed that the young grew rapidly during the first ten years, then the growth rate declined. 

During the first 5-10 years, they probably added approximately 0.3 meters (1 foot) of length per year.

Evolution and History

A genus of carnivorous crocodylomorph from the early jurassic
A genus of carnivorous crocodylomorph from the early jurassic | Nobu Tamura via Wikipedia CC BY 2.5

Like its relatives, the Deinosuchus is part of the Crocodylomorpha clade, whose members date back to the Late Triassic. 

The oldest known crocodylomorphs are the small, gracile sphenosuchians, which survived the Triassic-Jurassic Extinction Event.

Further down the evolutionary tree, the Deinosuchus is classified in the Crocodilia order and Alligatoroidea superfamily. 

The latter probably split from the crocodile-gharial lineage roughly 100-80 million years ago, and its oldest known genus is the Leidyosuchus.

Upon its discovery, the Deinosuchus was placed in the Crocodylidae family and considered a relative of true crocodiles. 

It was then named Phobosuchus riograndensis.

Two American alligators that belong to the Alligatoroidea superfamily
Two American alligators that belong to the Alligatoroidea superfamily | Matthew Field via Wikipedia CC BY-SA 3.0

Later, however, it was confirmed that this newly-discovered reptile should be a basal genus in the Alligatoroidea group. 

Over the years, numerous discoveries led to the naming and description of four species:

  1. Deinosuchus hatcheri
  2. Deinosuchus rugosus
  3. Deinosuchus riograndensis
  4. Deinosuchus schwimmeri

D. rugosus is known from Appalachia, while D. hatcheri and D. riograndensis are known from Laramidia.

However, apart from some minor differences between them, the individuals belonging to these species were roughly identical, which is why many scientists argue that they should be regarded as synonymous.

Interactions with Other Species

Deinosuchus lunges at a dinosaur species
Deinosuchus lunges at a dinosaur species | Raul D. Martin via National Geographic Stock

Considering how widespread the Deinosuchus was, listing all the creatures it shared its habitat with would be impossible, especially since many haven’t even been discovered yet!

However, if we also take notice of the fact that the Deinosuchus was primarily aquatic, we may assume that it didn’t, in fact, cross paths with many terrestrial creatures, except those that ventured near water edges and probably served as prey for the giant crocodile.

Either way, the habitat the Deinosuchus lived in was likely abundant with turtles like the Boremys, Denazinemys, and Neurankylus

It may have lived among other crocodiles but undoubtedly reigned over the environment, considering its gigantism and hunting skills.

Ornithischian dinosaurs were quite common. 

Small ornithischians may have fallen prey to the Deinosuchus if they were unlucky enough to cross their territory. 

Deinosuchus attacking a prey
Deinosuchus attacking a prey | image via survival evolved wiki

Larger dinosaurs may not have been spared if a favorable hunting opportunity appeared.

In locations like the Kaiparowits Formation, theropods were also quite common, including carnivorous theropods. 

However, the Deinosuchus probably did not compete for food with theropods and didn’t fall prey to any, as theropods were terrestrial and were no match for the Deinosuchus size.

Additionally, the Deinosuchus had the amazing advantage of being aquatic, and even if it tried to catch a terrestrial animal, it rushed back to the water. 

And if it felt threatened, there was no need to venture into the outside world, as the waters were rich in turtles, bony fish, and cartilaginous fish.

Cultural Significance

Deinosuchus was an apex predator
Deinosuchus was an apex predator | image via survival evolved wiki

Its large size and remarkable hunting skills earned the Deinosuchus an important place in our world’s evolutionary history. 

As such, it is now the subject of numerous research papers and studies aimed at discovering more about this reptile’s appearance, behavior, and lifestyle.

The Deinosuchus is quite popular in the media as well, which is good news for prehistoric wildlife enthusiasts who want to observe this gigantic reptile in motion. 

The Deinosuchus appears in Paleoworld, Walking with Dinosaurs, Dino Dan: Trek’s Adventures, and others. 

It is also a creature in three Jurassic Park video games.


The Deinosuchus lived in North America roughly 82-73 million years ago. 

It was an alligator crocodilian known from fossilized specimens found across the continent.

The terrible crocodile is often regarded as the largest known crocodyliform. 

However, its size hasn’t been fully confirmed yet, which is why there’s a large gap between the proposed minimum and maximum lengths and weights.

Regardless of whether it was indeed the largest, the Deinosuchus was undoubtedly a ferocious reptile capable of killing even large dinosaurs if opportunity presented itself. 

Some specialists even consider it an apex predator!


Can Deinosuchus beat T-Rex?

If a Deinosuchus ever confronted a T-Rex, it may have won the battle. 

However, the resolution of such a confrontation highly depends on where it occurs. 

The Deinosuchus would have the upper hand near water, as it would have been enough to grab the Tyrannosaurus and drag it into the water. 

On the other hand, the T-Rex would probably win if they fought each other farther away from water sources.

Is Deinosuchus bigger than Sarcosuchus?

The Deinosuchus was probably larger than the Sarcosuchus, as the latter measured only 9-9.5 meters (29.5-31.2 feet) long.

What killed the Deinosuchus?

While it is well-known that the Deinosuchus went extinct before the mass extinction event at the end of the Cretaceous, it remains a mystery what precisely killed these large reptiles.


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