Caribbean Islands Reveal Surprising Last Refuge of Ancient Terrestrial Crocodiles

Fossil discoveries in the Dominican Republic are reshaping scientists’ understanding of the final chapters in the history of a long-extinct group of fearsome land-dwelling crocodiles known as sebecids, Reuters reports.

The newly uncovered remains suggest these terrestrial predators persisted in the Caribbean millions of years longer than previously thought.

The fossils, consisting of a single tooth and two vertebrae, were found in 2023 and date back approximately 5 to 7 million years. They belonged to a sebecid, a group of extinct crocodilians known for their upright posture, long legs, and sharp, serrated teeth—traits that made them resemble predatory dinosaurs more than modern crocodiles.

“These were the type of predators that one thinks were from the dinosaur times,” said Lazaro Viñola Lopez, a paleontology graduate student at the University of Florida and lead author of the study published in the Proceedings of the Royal Society B. “It’s remarkable that they survived on these islands so long after they had disappeared from the mainland.”

Until now, the most recent known sebecid fossils were from Colombia, dating back about 10.5 to 12.5 million years. The new fossils from the Dominican Republic push the timeline forward by several million years, indicating that the Caribbean may have served as a final stronghold for these apex predators.

Sebecids were top land predators in South America during the age of mammals, sharing their ecosystems with other formidable creatures such as terror birds—giant, flightless birds with hooked beaks—and saber-toothed marsupials. Unlike their modern semiaquatic relatives, sebecids were fully terrestrial and adapted for speed and agility on land.

Though the Dominican Republic specimen is estimated to have been about 7 feet (2 meters) long, some sebecids grew up to 20 feet (6 meters). Their narrow, deep skulls and blade-like teeth were well suited for slicing meat, drawing comparisons to theropod dinosaurs.

Study co-author Jonathan Bloch of the Florida Museum of Natural History described the find as “amazing,” noting how these agile, meat-eating reptiles likely hunted native Caribbean species such as sloths and rodents.

Previous fossil finds in Cuba and Puerto Rico—dating as far back as 29 million years—suggest that sebecids were more widely distributed in the Caribbean than once believed. Researchers propose that these animals may have reached the islands from South America via temporary land bridges or island chains during a time when the distance between land masses was much shorter.

“The Caribbean islands served as a sort of biodiversity time capsule,” said Viñola Lopez. “They preserved lineages that had disappeared elsewhere, giving us a rare glimpse into an ecosystem that no longer exists.”