Giant croc-like carnivore fossils found in the Caribbean
Imagine a crocodile built like a greyhound—that’s a sebecid. Standing tall, with some species reaching 20 feet in length, they dominated South American landscapes after the extinction of dinosaurs until about 11 million years ago. Or at least, that’s what paleontologists thought, until they began finding strange, fossilized teeth in the Caribbean.
“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.
This initial confusion was warranted. Three decades ago, researchers uncovered two roughly 18 million-year-old teeth in Cuba. With a tapered shape and small, sharp serrations specialized for tearing into meat, it unmistakably belonged to a predator at the top of the food chain. But for the longest time, scientists didn’t think such large, land-based predators ever existed in the Caribbean.
The mystery deepened when another tooth turned up in Puerto Rico, this one 29 million years old. The teeth alone weren’t enough to identify a specific animal, and the matter went unresolved.
That changed in early 2023, when a research team unearthed another fossilized tooth in the Dominican Republic—but this time, it was accompanied by two vertebrae. It wasn’t much to go on, but it was enough.
The fossils belonged to a sebecid, and the Caribbean, far from never having large, terrestrial predators, was a refuge for the last sebecid populations at least 5 million years after they went extinct everywhere else.
A research team described the implications of their finding in a new study published in the Proceedings of the Royal Society B.
The study’s lead author, Lazaro Viñola Lopez, conducted the research as a graduate student at the University of Florida. He knew his team members had come upon something exceptional when they unearthed the fossils. “That emotion of finding the fossil and realizing what it is, it’s indescribable,” he said.
Sebecids were the last surviving members of the Notosuchia, a large and diverse group of extinct crocodilians with a fossil record that extends back into the age of dinosaurs. They represented a wide range in size, diet and habitat and were notably different from their crocodile relatives, as most of them lived entirely on land.
The sebecids acted like carnivorous dinosaurs, sprinting after prey on their four long, agile limbs and tearing through flesh with their notorious teeth. Some species could reach 20 feet in length and had protective armor made of bony plates embedded in their skin.
The mass extinction event 66 million years ago that wiped out nonavian dinosaurs nearly destroyed notosuchians as well. In South America, only the sebecids endured, and with the dinosaurs gone, they quickly rose to be the apex predator.
The open sea separating the Caribbean islands and mainland South America would have posed a serious challenge for a terrestrial sebecid to swim across. In finding the fossils, the research team revealed possible evidence in support of the GAARlandia hypothesis.