For more than 250 years, the stories of early explorers described crocodiles as a common sight along the Seychelles coast. However, with the arrival of settlers in 1770, the island’s population declined rapidly. Within about 50 years, crocodiles were completely extinct.
Now, through new genetic analysis, scientists have finally uncovered the identity of these vanished reptiles. The study revealed that the Seychelles crocodile is not a separate species, as once suspected. Rather, they were the westernmost known population of saltwater crocodiles (Crocodylus porosus), the world’s largest living reptile and one of the most capable ocean travelers.
DNA reveals the origins of the Seychellois crocodile
Researchers from Germany and the Seychelles investigated the evolutionary history of saltwater crocodiles by comparing DNA from modern animals with genetic material taken from historic museum specimens. The research team analyzed the conserved mitochondrial genomes of crocodilians belonging to the genus Crocodile. crocodilecontains valuable samples from a Seychelles population that disappeared approximately 200 years ago.
The discovery confirmed earlier theories that were based solely on the crocodile’s appearance. Genetic evidence shows that Seychelles’ animals are closely related to saltwater crocodiles that live thousands of kilometers away.
Crocodiles crossed long distances across the Indian Ocean
Among modern crocodiles, saltwater crocodiles are particularly well adapted to life in the sea. Specialized salt glands allow these reptiles to remove excess salt from their bodies and survive for long periods in seawater. Over time, this ability helped the species spread over vast areas of coastlines and remote islands.
“The progenitors of the Seychelles population must have drifted at least 3,000 kilometers across the Indian Ocean to reach remote islands, and maybe even further away,” said Frank Grow, reptile expert at the Bavarian State Natural History Collection (SNSB) and lead author of the study.
Scientists believe these crocodiles likely migrated on ocean currents over many generations, eventually establishing a population on a remote island in the Seychelles.
One of the world’s most widespread reptiles
“The genetic patterns suggest that saltwater crocodile populations remained connected over long distances over long periods of time, demonstrating the high mobility of this species,” said lead author Stéphanie Agne from the University of Potsdam.
Saltwater crocodiles are still one of the most widely distributed reptiles on Earth. Before the Seychelles population became extinct, the species ranged over a much wider range, spanning more than 12,000 km, from Vanuatu in the Pacific Ocean to the Seychelles in the Indian Ocean.
