Sampling of Seychelles crocodiles. Three incomplete skulls from the Seychelles National Museum are among the few preserved remains of Seychelles crocodiles
A DNA study reveals that the saltwater crocodiles that lived in the Seychelles (before the arrival of humans) represented the westernmost population of this species, having crossed the Indian Ocean to reach the island.
Saltwater crocodiles once occupied a huge distribution area that stretched across the entire Indian Ocean to the Seychelles – confirmed a study last week in RSOS Journal.
The now-extinct population was not a group of Nile crocodiles (Crocodylus niloticus), nor did it constitute a separate species. Instead, it was probably the westernmost population of saltwater crocodiles (Crocodylus porosus), which currently live in India, Southeast Asia, Australia, and islands throughout the Western Pacific-
“They will have swum at least 3,000 kilometers across the Indian Ocean to reach the remote archipelago, perhaps even much further,” said study co-author and reptile expert at the Bavarian State Natural History Collections in , Frank.
Although the Seychelles, an archipelago in the western Indian Ocean, was once home to a large population of crocodiles, when human settlers arrived in the late 18th century, they exterminated all the crocodiles on the islands.
Initially, Western scientists thought the Seychelles crocodiles were part of a population of Nile crocodiles that had migrated from Africa. However, in 1994, researchers reclassified the preserved remains as saltwater crocodiles based on their physical characteristics.
In the new study, a different team of scientists confirmed that conclusion by using mitochondrial DNA from skulls and teeth from several ancient museum specimens of different crocodile species and then comparing that DNA with tissue samples from modern museum specimens and living crocodiles.
As Live Science explains, to spread as far west as the Seychelles, C. porosus it would have to cross thousands of miles of ocean. However, crocodiles they are adapted to marine life, having special salt glands on their tongue that allow them to expel excess salt.
This adaptation may have helped animals spread widely across the Indo-Pacific region and limit further speciation, the researchers wrote in the new study.
