Science Saturday

Crocodiles Are Prehistoric Monsters Who Survived The Dinosaur's Extinction

It's not exactly headline news that alligators and crocodiles are basically living dinosaurs. Except they aren't dinosaurs. For one thing, they're still around, and just as scaly and scary as ever. But scientists recently put together a set of bones of one of crocodiles' earliest known ancestors, and it's just another piece of evidence that, monstrous or not, modern crocs have nothing on their ancient predecessors.

Paleoartistic restoration of the head of Razanandrongobe sakalavae. Unlike extant crocodilians, this terrestrial predator had a deep skull.

One Part Croc, One Part T-Rex, One Part Grizzly Bear, And One Part Armadillo

Meet Razanandrongobe sakalavae. She's more than just a pretty face. Actually, she's proof that crocodiles (or more accurately notosuchians, the ancestors of crocodiles) are much older than we previously thought. An example of an early notosuchian, "Razana" is an example of a ghost lineage, an evolutionary line that's been inferred but never discovered. She's no less than 163 million years old (that's 42 million years older than the next-oldest notosuchian that we've discovered), and compared to her descendants, she's a much different animal.

First, her teeth. Razana predated Tyrannosaurus Rex by about 100 million years, but Raz's teeth wouldn't have looked out of place in Rex's mouth. Then there's her legs, which are long enough to give her a body that's more like a bear or dog than a modern crocodile. Most astonishing of all, perhaps, is her armor, which was likely banded like an armadillo's. Oh, and some estimates place her upwards of 12 meters (39 feet) long — bigger than a city bus, which would make her the biggest of all time. Basically, Razana looked like she walked right out of a Godzilla movie. She was almost certainly the apex predator of her territory, and likely feasted on dinosaurs at every opportunity.

Paleontologists Cristiano Dal Sasso (left) and Simone Maganuco (right) standing next to the jaws of “Razana” at the Natural History Museum of Milan.

Slow And Steady And Full Of Razor-Sharp Teeth Wins The Race

Though Razana was much different from modern crocodiles, it only took a few dozen million years for the basic body plan of a croc to be standardized (some bizarre variations notwithstanding). They stayed giant for a long time, though.

One so-called "supercroc" was Sarcosuchus imperator, the previous record holder for size. This was an animal that would have looked a little more familiar to us (though pumped up to more-than-double today's crocs). Another find, this one from 2016, proved that the oceans weren't safe from the creatures either. Machimosaurus rex was a saltwater croc from 120 million years ago that clocked in at 9.6 meters (31 feet) long. Both of these monsters could have dined on dinos easily. And they're not very far off from the crocodilians that still exist today.

So how have crocodiles been able to survive on the planet for so long? What gives them their stubborn longevity? The truth is, it's hard to say. Seeing as how they've basically gone unchanged since dinosaurs walked the Earth, they've clearly got their niche carved out. And their incredible resilience has to have helped as well — crocs regularly survive lost limbs and other grievous wounds. The real key is probably their hunting habits. Crocodiles and their relatives wait in water until their thirsty prey gets too close, then they strike. As long as crocodiles can blend into a muddy pool and as long as animals need water to drink, they'll probably be just fine. And if there were still dinosaurs around, they'd probably still be getting eaten by their distant cousins.

Watch And Learn: Our Favorite Videos About Giant Crocodiles

Giant Crocodiles From "Walking with Dinosaurs"

Written by Reuben Westmaas July 10, 2017

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