A groundbreaking fossil discovery in the Dominican Republic reveals that ancient species of crocodiles, known as sebecids, thrived on Caribbean islands for millions of years after their South American counterparts went extinct.
The Age of Dinosaurs came to an abrupt close 66 million years ago, marking the end of non-avian dinosaurs and other major reptile groups at the end of the Cretaceous Period. However, in South America, a different story unfolded. Sebecids, relatives of crocodilians, survived the mass extinction event and thrived as top predators on the continent for tens of millions of years.
Sebecids were a group of large, carnivorous marine reptiles that lived during the Cretaceous period.
They belonged to the family Sebecidae and were characterized by their long, narrow snouts and powerful jaws.
Several sources indicate this Sebecids were likely apex predators in their ecosystems, feeding on fish, squid, and other marine animals.
Fossil records “indicate” that sebecids were widespread across what is now North America, with some species reaching lengths of over 6 meters.
For decades, sebecid fossils from after the end of the Cretaceous extinction have been found in South America and more limitedly in Europe. However, mysterious, serrated teeth also kept popping up at fossil sites in the Caribbean: first in Cuba, then in Puerto Rico. The identity of these crocodile-like groups was unclear due to multiple overlapping characteristics.
Recently, researchers working in the Dominican Republic uncovered a 12 millimeter-long fossilized, serrated tooth thought to belong to a late surviving sebecid. This find is significant not only because it provides conclusive evidence of sebecids’ presence in the Caribbean but also because it pushes back their extinction date by millions of years.
The vertebrae and tooth from the Dominican Republic are much younger than all those fossils — between roughly 4 million and 7 million years old. This discovery suggests that sebecids held on in the Caribbean long after their South American counterparts died out. These mysterious predators would also be the last of the notosuchians, a broader group of reptiles that first appeared in the Jurassic Period.
It’s possible that sebecids were incrementally squeezed into tropical latitudes by a changing, cooling climate over millions of years, says Jonathan Bloch, a vertebrate paleontologist at the University of Florida and research team member. Their range eventually contracted to just the islands, where they likely thrived in a variety of ecosystems.
The findings have implications for how researchers understand the evolutionary history of the Caribbean. For instance, there are many independent instances of various now-extinct birds evolving to be more ground dwelling or even fully flightless. The presence of sebecids on these islands challenges this assumption, suggesting that land predators may have played a significant role in shaping the evolution of island ecosystems.
The sebecid from the Dominican Republic may have measured about two meters long, and other species were known to be much larger — like Barinasuchus, one of the last sebecids from South America, which could have been 10 meters long and weighed nearly two metric tons. These powerful carnivores were probably extinct on the islands by the time the birds turned to flightlessness.
Barinasuchus is an extinct genus of crocodylomorph that lived during the Early Cretaceous period.
It was discovered in Venezuela and named after the state of Barinas.
This prehistoric creature measured around 8 meters in length and weighed several tons.
Its fossil remains were found in a layer of sedimentary rock, providing valuable insights into its anatomy and behavior.
Scientists have reconstructed its skull, revealing a mix of primitive and advanced features.
The discovery of sebecids in the Caribbean is a surprising revelation that sheds new light on the evolution of these fascinating creatures. It highlights the complexity and diversity of ancient ecosystems, where even the most unexpected predators can thrive in unexpected environments.
