(CN) - Millions of years ago, the Caribbean wasn't the peaceful island chain we think of today. It was a hunting ground for giant, land-roaming predators built more like sprinting greyhounds than the crocodiles we know.
The discovery, described in a new study published in Proceedings of the Royal Society B, shows the Caribbean was home to these land-based hunters long after they vanished from mainland South America.
Paleontologists found remains of sebecids - fast, meat-eating reptiles with long limbs and serrated teeth - in the Dominican Republic, Puerto Rico and Cuba.
Researchers say these predators lived for millions of years after the dinosaurs disappeared, taking over as top hunters across the islands. Some grew up to 20 feet long, with serrated teeth and bodies built for chasing prey.
Until recently, scientists didn't think these kinds of large predators had ever made it to the Caribbean islands.
"The first question that we had when these teeth were found in the Dominican Republic and on other islands in the Caribbean was: What are they?" said Jonathan Bloch, curator of vertebrate paleontology at the Florida Museum of Natural History, in a press release.
Three decades ago, researchers uncovered two ancient teeth in Cuba. Another turned up in Puerto Rico. Their size and shape suggested a top predator, but without more fossils, the mystery remained unsolved.
That changed in 2023, when a research team found another tooth in the Dominican Republic, along with two vertebrae. According to researchers, it was finally enough to confirm that the fossils belonged to a sebecid.
"That emotion of finding the fossil and realizing what it is, it's indescribable," said Lazaro Vinola-Lopez, the study's lead author, who conducted the research as a graduate student at the University of Florida, in the press release.
Sebecids were the last survivors of a larger group called notosuchians, ancient crocodile relatives that lived entirely on land. After the extinction that wiped out nonavian dinosaurs 66 million years ago, sebecids rose to dominate South America's ecosystems, researchers said.
How they reached the Caribbean is still an open question.
According to researchers, the open sea would have been a serious barrier for animals that lived on land. But the finding supports the GAARlandia hypothesis, an idea that temporary land bridges or a chain of islands once allowed animals to move from South America into the Caribbean, according to researchers. If other Caribbean teeth also belong to sebecids, it means these predators helped shape island ecosystems in ways researchers are only now beginning to understand.
"You wouldn't have been able to predict this looking at the modern ecosystem," Bloch said. "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."
Today, most fossil discoveries in the Caribbean come from caves and blue holes, where remains are better preserved. These sites mostly hold more recent fossils, offering only a partial look at ancient biodiversity.
Paleontologists like Vinola-Lopez are now focusing on finding older fossils, even if it means jumping at short-lived opportunities when new outcrops are exposed.
"Outcrops don't last too long, so you go there when you can. When they're cutting the road or a few months after that, you find the fossils. If you're looking in a few years, it will be gone," Vinola-Lopez said.
The sebecid discovery is part of a larger wave of fossil finds across the Caribbean, including mosasaurs, ancient marine reptiles, and the oldest known ground sloth bones on Hispaniola.
Researchers are also piecing together how the arrival of humans may have led to the extinction of native island rodents.
"The sebecid is only the tip of the iceberg," Vinola-Lopez said.
Source: Courthouse News Service
