There are currently 28 species of crocodiles, but that is only a fraction of all the different ones that have walked the Earth. There are some very strange guys among them. It’s high time to delve into the surprisingly complex history of the crocodile.

Crocodiles appeal to the imagination, perhaps because of their outright ugliness or because of that large dangerous mouth full of sharp teeth, either way: we want to know more about that. That’s what the British paleontologists must have thought when they decided right away two studies to devote to. They discovered where the cradle of the dangerous animals was and how they spread across the world. They also studied why they grow so slowly and what was on the menu of the scaly creatures over all those millions of years.

Fresh or salt water
The first large, modern group of crocodilians probably arrived in Europe about 145 million years ago. Not long after, the ancestors of today’s crocodiles and alligators split in North America, with crocodiles, unlike alligators, quickly becoming at home in salt water. That made it a lot easier for the crocodiles to penetrate every corner of the world. “It is likely that the ancestors of modern alligators and crocodiles evolved in North America and that the alligator family – which includes both alligators and caimans – remained in North, Central and South America, while crocodiles are much further afield. have moved away,” explains Professor Paul Barrett Natural History Museum out in London.

All different
That’s probably because they like salt water. “It appears that the ability to move through salt water has made crocodiles much more widespread across the Earth than alligators. Crocodiles even live in tropical oceans, while alligators only thrive in fresh water and therefore have never reached some areas. Different crocodile species originated and flourished in very different regions,” said the British paleontologist.

With their thick armored skin, large teeth, sluggish lifestyle and predatory habits, crocodiles are often seen as the same monsters that walked the Earth alongside the dinosaurs hundreds of millions of years ago. But that is absolutely not true. Crocodilians have a rich and varied evolutionary history. There are hundreds of surprising species in the large group called Crocodylomorpha, which also includes modern crocodiles, alligators, gharials and caimans. Unfortunately, they all became extinct over time.

From dinosaurs to insects
The species that remained are all carnivores that are used to living in the water, waiting for their prey. But this was very different 200 million years ago. “Some of these animals were large predators that preyed on dinosaurs,” Barrett says. “But others were small, light-footed animals that probably mainly had insects on their menu. There were even several species of herbivorous crocodilians, with a very complex – almost mammal-like – row of teeth, which may have chewed plants before swallowing.” There was the Simosuchus, which looked somewhat like an armadillo with a short snout, but which probably fed on fruits, tubers and ferns. There were also lightly built runners, such as Terrestrisuchus, which looked more like a reptilian version of the greyhound.

Lost diversity
“Crocodiles and their relatives experimented wildly in appearance, diet and lifestyle. They were doing a surprising number of things, very different from modern crocodiles, which all perform somewhat the same trick,” says Barrett. “Living crocodiles show only a shadow of the diversity they and their ancestors displayed in the distant past.”

Slow growth

Crocodiles grow relatively slowly, especially compared to their closest living relatives, birds. It takes years for them to reach their maximum size. Birds can do that in less than a year and chickens in about 150 days. According to a recent study, also by Barrett, this difference arose early in evolution. “Our new results show that the stark difference we see between living, fast-growing birds and their slow-growing relatives, the crocodiles, arose very early in the group’s evolutionary history, even though their common ancestor was a fast grower.” , Barrett said.




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