Fossil of Massive Crocodile Found on Edge of Sahara Desert

The creature from the Cretaceous was twice the size of anything seen today.

Paleontologists have discovered the fossil remains of the world's biggest ocean-dwelling crocodile buried on the edge of the Sahara, a creature that was twice the size of anything seen today.

Named Machimosaurus rex, this croc would have weighed in at least 6,600 pounds and been around 32 feet long. Other than its size, it would have looked much like a modern day crocodile except for its narrow snout – which was designed to allow it swim in the ocean.

It would have been the top predator in what was then an ocean that separated Africa from Europe about 130 million years ago.

"This is an incredibly big crocodile. It is twice as big as a present day marine crocodile," University of Bologna's Federico Fanti, who was part of the team that made the discovery with support from the National Geographic Society Committee for Research and Exploration, told

"The skull itself is as big I am," said Fanti, whose discovery was detailed in a study in the journal Cretaceous Research. "Just the skull is more than five feet long. It's a massive crocodile."

Tunisia, where the skeleton and some bones were found, would have been a lagoon facing the ocean and the environment would have been filled with huge fish and turtles – all favorite prey of the Machimosaurus rex.

"This animal, however, used to feast on the large turtles or big fishes that it found in the ocean," Fanti said. "He was so big and so powerful that it was absolutely at the top of the food chain."

Beyond its size, Fanti said the significance of the find is what it tells us about a mass extinction event that is believed to have happened between the Jurassic and Cretaceous period about 150 million years ago. Machimosaurus rex was thought to have died out then but the discovery suggests the extinction event was not as widespread as some paleontologist thought.

"The fact that Machimosaurus rex (pertaining to a group that was well alive in the Jurassic) lived 130-120 million years ago indicate that there was no mass extinction," Fanti said.

"Everyone thought this group of crocodiles went extinct in the Jurassic but we found it well into the Cretaceous," he said. "We simply extended the temporal range of the animals. Twenty million years is a lot of time."

Fanti, whose team has discovered 20 new species including a rebbachisaurid sauropod Tataouinea hannibalis in the same area, said there is less to learn about crocodile evolution from this new discovery. The reason, he said, is that crocodiles have changed little over time.

"Basically, they are bigger or smaller," he said of their evolution, adding that even bigger crocodiles lived on land, many of which also have gone extinct. The largest freshwater crocodile, Sarcosuchus imperator, lived 110 million years ago and grew as long as 40 feet (12 meters). It weighed up to 17,500 pounds, according to National Geographic.

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Crocodiles are fun-loving, finds a new study on the toothsome predators. Since play is associated with intelligence, the findings, published in the latest issue of the journal Animal Behavior and Cognition, suggest that crocodiles are smarter and much more social than previously thought. They also appear to have a romantic side. Author Vladimir Dinets of the University of Tennessee, Knoxville, believes that croc "courtship might involve elements of play that are often difficult to recognize as such. I observed and photographed a pair of adult Cuban crocodiles at Zoo Miami (shown here) performing a particularly unusual behavior at the time of courtship: the female would get on the back of the larger male, and he would give her a few rides around the pool." Dinets has also seen young crocodiles enjoying piggyback rides offered by larger adults.

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Dinets has studied crocodiles for over a decade, during which time he has long-suspected that they play -- and enjoy it. For the new paper, he compiled his own observations of crocodiles playing. He added these to other published and unpublished reports. The survey found crocodiles engage in all three main types of play known in the animal kingdom: locomotor play, play with objects and social play. While such activities offer benefits, such as forging social connections and facilitating learning, the immediate reward is pure pleasure. Prior research conducted by renowned animal behaviorist Jonathon Balcombe concluded that crocodiles do feel pleasure. The feelings arise via the release of happiness-promoting chemicals like the neurotransmitter dopamine. This sunning croc appears to be feeling no pain.

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Crocodiles are incredibly strong and toothy predators, so most other animals -- including humans -- can serve as prey for them. Crocodiles, however, have been seen playing with other animals, according to Dinets. Crocs have even forged long-term bonds with species that they might otherwise eat.

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Like dogs, crocodiles will sometimes play with their food. For example, they may spend time investigating bones, chewing on them, and tossing them around, long after the meat on them has been gnawed off.

Alligators enjoy playtime too, Dinets discovered. He spotted this American alligator resting after a "bout of play with a stream of water" at the Saint Augustine Alligator Farm Zoo Park in Florida. As for a human standing under a shower, the falling water likely offered a nice massage on the alligator's body.

Dinets has seen crocodiles playing with flowers on several occasions. He snapped a Cuban crocodile at Zoo Miami in Florida (left) playing with Bougainvillea flowers. He also photographed a West African dwarf crocodile playing with the same type of flower at Madras Crocodile Bank in Tamil Nadu, India. It could be that the color and texture of this particular flower is somehow appealing to crocodiles.

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Prior research conducted by Gordon Burghardt at the University of Tennessee, Knoxville, found that crocodiles are more likely to play under certain circumstances. "The behavior is initiated when the animal is adequately fed, healthy, relaxed, and free from stress, such as predator threat, harsh microclimate, (and) social instability, or intense competing systems, such as feeding mating (and) predator avoidance," Burghardt wrote. It could be that most, if not all, social animals enjoy some form of play. The conditions described by Burghardt could apply to humans, dogs, cats, birds and countless other species that only play when they are free from stress and predators.

Food provides its own reward, but crocodiles seem to enjoy food games too. This individual, for example, lunges toward a hotdog skewered on a twig. The behavior is probably comparable to a dog or cat eagerly chasing after a yummy treat. Crocodiles like toys too, according to Dinets. "Hundreds of thousands of crocodilians are now kept in captivity in zoos, commercial farms and breeding centers set up for endangered species," he said. "Providing them with toys and other opportunities for play makes them happier and healthier."

Crocodiles are among the oldest animals on earth, since their ancestors were around at least 200 million years ago. Modern crocodiles date back to around 80 million years ago. These ultimate survivors used to exist around—and eat—non-avian dinosaurs, which they have clearly since outlived. So long as their habitats offered comforts and food, crocodiles were probably enjoying playtime for tens of millions of years before the first humans even appeared.

While close encounters with crocodiles are not advised, Dinets said that there are rare cases where crocodiles have bonded so strongly with people that they have become playmates for years. The crocodile shown in this image has had regular human contact, and therefore does not seem to mind the close proximity of people, one of which is nearly sitting on the croc. Dinets described an instance where a man rescued a crocodile that had been shot in the head. The croc recovered and did not seem to forget the kindness of his human savior. Dinets said, "The croc would swim with his human friend, try to startle him by suddenly pretending to attack him or by sneaking up on him from behind, and accept being caressed, hugged, rotated in the water and kissed on the snout." He added that the two played happily together every day until the crocodile died 20 years later.