For over thirty years, paleontologists have been unearthing peculiar serrated teeth on Caribbean islands. These sharp, prehistoric teeth hinted at the existence of large land predators, a puzzling discovery given the established understanding of the region’s fauna. Recent research has finally shed light on these mysterious fossils.
A team of international researchers has identified these remains as belonging to sebecids, a group of extinct, terrestrial crocodilians. These creatures, described as resembling a “crocodile built like a greyhound,” roamed the Caribbean millions of years ago, surviving until roughly five million years ago—long after their South American relatives went extinct around 11 million years ago. This discovery, published in Proceedings of the Royal Society B, strengthens the theory of ancient land bridges or island chains connecting the Caribbean to South America.
Figure 1: Fossilized sebecid tooth and vertebrae discovered in the Dominican Republic.
The breakthrough came in 2023 with the discovery of a fossilized tooth alongside two vertebrae in the Dominican Republic. This crucial find allowed scientists to definitively identify the remains as belonging to sebecids. The fossils have been dated between 7.14 and 4.57 million years ago, significantly later than the extinction of their South American counterparts. This discovery was a pivotal moment for the researchers, as lead author Lazaro Viñola Lopez, a paleobiologist at the Florida Museum of Natural History, described the excitement of identifying the fossils as “indescribable.”
Figure 2: Artist’s rendition of a sebecid.
Some sebecids could grow up to 20 feet (6.1 meters) in length. These carnivorous predators pursued their prey on four long legs. In South America, sebecids were the sole surviving members of the Notosuchia, a larger group of extinct crocodilians, after the asteroid impact that wiped out the dinosaurs 66 million years ago. This extinction event paved the way for sebecids to ascend the food chain.
Figure 3: Possible routes of sebecid dispersal to the Caribbean.
The presence of sebecids in the Caribbean lends credence to the GAARlandia hypothesis, which proposes the existence of either land bridges or island chains connecting South America and the Caribbean millions of years ago. This connection would have facilitated the migration of South American animals, including sebecids, to the Caribbean. The subsequent disappearance of this passageway would have isolated the Caribbean sebecids, potentially shielding them from the extinction event that impacted their South American relatives.
If further research confirms that similar teeth discovered on other Caribbean islands also belong to sebecids, it would signify the profound impact these apex predators had on the region’s ecosystem for millions of years. This presence would have shaped the ecological landscape in ways not readily apparent from the current fauna. Today, most Caribbean predators, such as birds, snakes, and even crocodiles, are considerably smaller.
The discovery of these sebecid fossils highlights the dynamic nature of prehistoric ecosystems and underscores the importance of paleontological research in understanding the complex history of life on Earth. This unexpected finding demonstrates that sometimes, even the most unlikely scenarios can be revealed through scientific investigation.
