Modern Crocodiles Are Evolving at a Rapid Rate
Despite their reputation as “living fossils,” crocodiles have changed dramatically in the last two million years
Riley Black
Science Correspondent
October 7, 2021
A gharial has the same skull shape as some extinct crocodiles. This skull shape has likely evolved three different times during the history of crocodiles. DeAgostini / Getty Images
Crocodiles look like they belong to another time, an era when reptiles ruled. But appearances can be deceiving. Today’s crocodiles are not holdovers that have gone unchanged since the Jurassic, but are one expression of a great, varied family that’s been around for over 235 million years. More than that, crocodiles are still evolving—and faster than they have at other times in their family’s scaly history.
The seemingly contradictory conclusion about crocodylian evolution comes from a recent study published in Proceedings of the Royal Society B by University College London anatomist Ryan Felice and colleagues. By comparing three-dimensional models to track anatomical landmarks on crocodylian skulls over time, the researchers found that modern crocodile species in Australia, southeast Asia and the Indo-Pacific are evolving quickly despite looking like semi-aquatic antiques. Modern croc species look so similar not because of conserving ancient traits, but because crocodiles are evolving the same skull shapes over and over again through time.
“Crocodylians just seem ancient and primordial and look a bit like Hollywood dinosaurs,” Felice says, not to mention that some species are among the largest reptiles on the planet. American alligators can grow to be 14 feet long, and saltwater crocodiles can get to be over 20 feet in length. On top of that, Felice notes, some fossil crocodiles superficially resemble living species. The spitting reptilian image can create a narrative that crocodiles haven’t changed much at all, content to lurk in the evolutionary backwaters. But that’s not the real story.
Today’s alligators, crocodiles and gharials—grouped together as crocodylians—shared a common ancestor back in the Cretaceous, around 95 million years ago. But crocodile history goes much deeper. Today’s alligators and crocodiles are just the remaining members of a broader, older group of reptiles called pseudosuchians—or crocodiles and their extinct relatives. The first pseudosuchians evolved over 235 million years ago, around the time that the first dinosaurs were making their mark on the Triassic landscape, and have gone through a vast array of changes through time.
More:
https://www.smithsonianmag.com/science-nature/modern-crocodiles-are-evolving-rapid-rate-180978432/
= new reply since forum marked as read
I’m sorry, but that took me straight to one inevitably named Bob. He’d be a Bobdylian!
