When a team of palaeontologists uncovered a fossilised tooth and two vertebrae on a newly cut roadside in the Dominican Republic in 2023, they knew they had found something important.
The fossils belonged to a sebecid, the last of a strange, mostly land-dwelling crocodilian group called Notosuchia, which originated in the age of dinosaurs.
Unlike their modern relatives, most sebecids lived entirely on land, running swiftly after prey on their four long limbs. These top predators grew up to six metres long, armed with razor-edged teeth and a thick coat of bony armour. They roamed widely across South America after the extinction of the dinosaurs.
Until recently, scientists believed sebecids disappeared from the planet around 11 million years ago. But the new fossil discovery in the Dominican Republic has turned that theory on its head, proving that these ancient crocodile relatives once prowled Caribbean islands, surviving at least 5 million years after their mainland cousins had vanished.
"That emotion of finding the fossil and realising what it is, it's indescribable," says researcher Lazaro Viñola Lopez, who led the study as a graduate student at the University of Florida. The findings were published in the Proceedings of the Royal Society B.
The discovery also breathes new life into the 'GAARlandia' hypothesis – the idea that a series of land bridges or stepping-stone islands once connected South America with the Caribbean, allowing animals such as sebecids to cross over. Until now, it seemed unlikely that large, land-based predators could have made the journey across open ocean.
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The 2023 discovery isn't the only sebecid evidence found in the Caribbean. Three decades ago, researchers uncovered two 18-million-year-old teeth in Cuba. Then another tooth turned up in Puerto Rico, this one 29 million years old. But these specimens weren't enough to identify a specific animal.
The new fossils not only confirm the identity of the teeth but show that sebecids were alive in the Caribbean far later than previously thought.
The sebecid discovery in the Caribbean changes our understanding of the region’s ancient ecosystems, says Jonathan Bloch of the Florida Museum of Natural History. "The presence of a large predator is really different than we imagined before, and it's exciting to think about what might be discovered next in the Caribbean fossil record as we explore back further in time."
Excitingly, this is just one of several major fossil finds in the Caribbean in recent years – from giant sea-dwelling mosasaurs to the earliest-known ground sloths.
Fuelled by these incredible discoveries, local researchers are now focusing on older, harder-to-reach fossils. "This is like a renaissance," says Viñola-Lopez, adding that “the sebecid is only the tip of the iceberg.”
Find out more about the study: A South American sebecid from the Miocene of Hispaniola documents the presence of apex predators in early West Indies ecosystems
Main image: roadside (not the fossil discovery site). Credit: Getty
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