Crocodiles from the Crypt Two distinct croc species inhabited the Nile in ancient times

Crocodile DNA, Credit: Bernard DUPONT, FlickrCCIn studying mummified crocodiles from ancient Egyptian temples, scientists discovered that two distinct crocodile species once lived in the Nile River, both of which are now endangered. The study, which included DNA analysis of living and historical crocs, was published in the journal Molecular Ecology, and included the finding of a distinct species from ancient times, Crocodylus suchus.

Increasing use of DNA sequencing technology has brought to light a greater understanding of genetic diversity in species. Biologists have a name for these species that were previously thought to be the same but are genetically different—cryptic species. A striking example of a cryptic species is the African elephant, which was discovered in 2001 to be two distinct species incapable of breeding with each other—the African bush elephant and the African elephant.

The discovery of cryptic species for the Nile crocodile is not only important from an academic point of view for proper classification, but also from the standpoint of maintaining genetic diversity and preserving the distinct species. According to recent surveys, the older species, C. suchus, is declining within modern day populations. For an already endangered species, the Nile crocodile’s two distinct species make each more rare than previously thought and in need of different conservation efforts.

Sustainable harvest of Nile crocodiles is allowed through conservation agreements in some African countries; but illegal skin and meat trade and damage to wetlands threaten the crocodiles. In order to protect the newly discovered cryptic species, the researchers urge “precautionary measures, such as recognizing the ancestral lineage as C. suchus on the IUCN Red List [of threatened species].”