Scientists have resolved a 250-year-old mystery regarding the crocodiles that once inhabited the Seychelles islands. Genetic analysis of historic museum specimens revealed that these reptiles were not a unique species. Instead, they were an isolated population of saltwater crocodiles, *Crocodylus porosus*.
The saltwater crocodile is the world's largest living reptile. It is known for its ability to travel vast distances across oceans. Researchers from Germany and the Seychelles compared DNA from modern crocodiles with genetic material from the extinct Seychelles population. This comparison included mitochondrial genomes from preserved *Crocodylus* specimens.
The findings support an earlier theory based on physical appearance. The genetic evidence shows a close connection between the Seychelles crocodiles and saltwater crocodiles located thousands of kilometers away. Saltwater crocodiles possess specialized salt glands. These glands allow them to remove excess salt, enabling long periods of survival in seawater.
This adaptation facilitated their spread across extensive coastlines and remote islands. Frank Glaw, a reptile expert from the Bavarian State Collections of Natural History, stated that the Seychelles population's founders likely drifted at least three thousand kilometers across the Indian Ocean. They may have traveled even further to reach the archipelago.
Stefanie Agne of the University of Potsdam noted that genetic patterns suggest saltwater crocodile populations maintained connections over long periods and distances. This indicates the species' high mobility. Before the Seychelles population's extinction, the saltwater crocodile's range spanned over twelve thousand kilometers. This range extended from Vanuatu in the Pacific Ocean to the Seychelles in the Indian Ocean.
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