The old terrestrial crocodile that rewrites the history of the Antilles

For millions of years, the Caribbean islands were a separate world, a natural laboratory of island evolution with unique species that grew, adapted or disappeared without hardly continental interference. But a recent finding in the Dominican Republic has completely shaken what we thought about knowing about the ancient Caribbean ecosystems: under a freshly open road the fossil of an old Earth’s crocodile appeared, A carnivore six meters long, biped and armed with sawn teeth that ruled these islands as the true king of the food chain.

The discovery, led by the paleontologist Lázaro W. Viñola López and published in the magazine Proceedings of the Royal Society Breveals that this predator was not a simple visitor, but an established member of the fauna of the older Antilles, a survivor of an extinct lineage in the South American continent for more than five million years. This finding not only fills a vacuum in the evolutionary history of the Caribbean, but completely rewritten the role that these islands played in the conservation of extinguished lineages of the continent.

A monster of the past on the highway

It all started in a road cut northeast of Santo Domingo, in an area called Sabana Grande de Boyá. There, embedded in sediments between 7.1 and 4.5 million years old, paleontologists found a cervical vertebra, another flow and a tooth shaped like shaving blade. The pieces did not belong to any modern crocodile. Its morphology indicated a terrestrial lifestyle, with a high body of the soil, a bite specialized in tearing meat and a typical denture of the Sebecos, a group of extinct terrestrial crocodiles that were believed to be limited to South America.

The Sebécidos were the last survivors of the Notosuchia clado, a lineage of terrestrial crocodiles that emerged in the Cretaceous and even resisted the extinction that ended the dinosaurs. In the South American continent, they were the dominant predators after the disappearance of the great theropods, occupying the niche of the land carnivores with great efficiency. They had high skulls, long legs and a bite that could compete with that of any mammal predator. They were, in many ways, the postdinosourian equivalents of the velociraptors.

Until now, the last South American fossils of Sebecidos dated about 10 or 11 million years ago. The discovery in the Dominican Republic not only extends in more than five million years the survival of the group, but also places it in a region where its presence had never been confirmed so clearly. Previously, isolated teeth had been found in Cuba and Puerto Rico, but their attribution was uncertain. This finding gives them a context, confirmation and a story.

Gaarlandia’s footprint

The study not only describes a new fossil. It also revives an old geological debate: The existence of a land bridge or archipelago called Gaarlandia that, between Eocene and Oligocene, would have briefly connected northern South America with the elderly Antilles. This structure, already sunk, would have allowed the migration of terrestrial fauna – mamifers, amphibians, reptiles – along a chain of islands or emerged lands, on a trip that was previously believed impossible for non -aquatic animals.

The arrival of a predator as specialized as the Sebate fits perfectly with that hypothesis. He could not swim great distances and, nevertheless, he appeared in three different islands. If these animals reached the Antilles more than 30 million years ago, as the teeth found in Puerto Rico (29 million years) and in Cuba (18 million) suggest, it means that they not only arrived, but also remained for tens of millions of years, surviving extinctions that ended their continental relatives.

A very different Caribbean

Today, when we think of depreders from the Caribbean, birds come to mind raptors, snakes or even the famous Cuban crocodile. But six million years ago, these animals shared their territory with a terrestrial monster six meters long, capable of demolishing giant lazy, rodents of the size of islands or island primates. Its single presence completely changes the ecological panorama of the Caribbean Neogen.

The remains of the Sebécido found in the Dominican Republic were associated with fossils of freshwater turtles, South American, lazy and crocodiles of Aligator type. Together, this fauna suggests a mixed ecosystem of plains, rivers and forested areas, where multiple species coexisted with both terrestrial and semi -communicative predators. Interestingly, Sebecides do not appear in the minor islands, which reinforces the idea that their dispersion was not a product of chance, but of a concrete terrestrial connection.

Besides, The disappearance of the Caribbean Sebécido coincides with the period of greater ecological transformation in the Caribbean: the closure of land connections, the elevation of sea level and the isolation of the major islands. Without competitors or new predators, the Sebecid was probably extinguished due to loss of habitat or lack of dams, opening the way for carnivorous birds and more general crocodiles to occupy their place.

The last lair of the notesuquios

The discovery is even more important: The Sebecides of the Antilles were the latest known representatives of the Notosuchia group throughout the planet. This crocodile lineage, which once populated Africa, Europe and South America, disappeared in the continent but survived in the islands. As has happened with other animal groups, the islands acted as an evolutionary refuge, a “biodiversity museum” where extinguished lineages in the continent persisted in relative isolation.

This phenomenon has also been observed with giant lazy, caviomorphy rodents or terrestrial turtles. The islands preserve ancient lineages not only for their isolation, but because they are often free from the predators and ecological pressures that push evolution in the continent. In this case, the predator was the one who had taken refuge.

A unique rediscovery

The finding in Sabana Grande de Boyá could be just the beginning. Most of the paleontological investigations in the Caribbean have focused on caves, but this fossil appeared in an outdoor outcrop, during the construction of a road. This suggests that many more remains, older and better preserved, could be waiting under the surface of these tropical islands.

Future excavation campaigns are already underway, and it would not be strange that in the coming years we discover other extinct species, new lineages or even evidence of unpublished ecological interactions between continental and antillean fauns. This finding is not only that of a fossil, but the opening of a door to the profound past of the Caribbean.