Sprinting Crocs With ‘Legs Like Greyhounds’ Once Ruled the Caribbean

Over the past three decades, paleontologists have been uncovering sharp, serrated, prehistoric teeth on Caribbean islands. The strange part? According to scientists, the owners of such teeth—large land predators—were never supposed to exist there.

But an international team of researchers has found that millions of years ago, a freakishly tall crocodile-like land predator called a sebecid roamed the Caribbean—surviving there until about five million years ago, long after its South American relatives died out around 11 million years ago. The findings bolster the theory that land bridges or a chain of islands once connected the Caribbean to South America.

In 2023, researchers found another fossilized tooth in the Dominican Republic, this time with two vertebrae, allowing them to finally identify the remains as belonging to sebecids. As detailed in a study published Wednesday in Proceedings of the Royal Society B, experts dated the fossils to between 7.14 and 4.57 million years ago—more than three million years after their South American cousins vanished. “That emotion of finding the fossil and realizing what it is, it’s indescribable,” study lead author Lazaro Viñola Lopez, a paleobiologist at the Florida Museum of Natural History, said in a museum statement.

According to the statement, some sebecids—described as tall “crocodile[s] built like a greyhound”—could reach up to 20 feet (6.1 meters) long. They were meat eaters, chasing after their prey on four long legs. In South America, they were the only members of the Notosuchia—a large group of extinct crocodilians—to survive the infamous asteroid that decimated the dinosaurs 66 million years ago. With that pesky competition no longer in play, sebecids quickly rose up the food chain.

But how could the land-based predators have reached islands in the Caribbean? The researchers say these results support the GAARlandia hypothesis—the idea that, millions of years ago, either land bridges or island chains allowed South American animals like sebecids to reach the Caribbean. When the passageway disappeared, sebecids would have been isolated from whatever threat caused their relatives in South America to disappear millions of years before them.

If researchers confirm that the strange teeth from other islands also belonged to sebecids, it means these apex predators impacted the region’s ecology for millions of years. That’s despite the fact that “you wouldn’t have been able to predict this looking at the modern ecosystem,” said Jonathan Bloch, a co-author of the study and curator of vertebrate paleontology at the Florida Museum of Natural History. Today, most Caribbean predators, such as birds, snakes, and even crocodiles, are significantly smaller.

Nevertheless, the study goes to show that where there’s smoke, there’s probably a fire—or in this case, a sprinting, extinct croc built like a greyhound.