The crocodiles that swam the Atlantic

Amazing link discovered between New World and Nile crocodiles

September 2011: Startling new research has uncovered evidence suggesting crocodiles swam across the Atlantic Ocean from Africa in order to establish the species in the Americas.

OCEAN VOYAGE: Crocodiles in the Americas and Africa have remarkably similiar DNA.

Scientists from the University of California and the American Museum of Natural History examined the mitochondrial genes of most of the 12 species of true crocodiles. The team, headed by Dr Evon Hekkala, discovered that the close genetic relationship between New World crocodiles and the Nile crocodiles of Africa.

The relationship seemed so close that it indicates a very recent split, according to Dr Hekkala, who suggests the crocodiles would have crossed the Atlantic sometime between three and seven million years ago - well after the Atlantic Ocean reached its present width.

‘People talk about crocodiles as an ancient lineage that is static, like the dinosaur,' said Dr Hekkala, a specialist in evolutionary biology and conservation genetics. ‘Our evidence suggests that the diversification in the true crocodile has arisen during the same period of time that modern humans arose, which is relatively recent, suggesting that the crocodile evolution is actually a very dynamic phenomenon.'

Because the Atlantic Ocean was approximately the same size at that time as it is today, the crocodiles' sea journey could have taken some months, said Dr Hekkala, although they may have been helped along by equatorial currents.

Crocodiles can go up to a year without feeding and were able to process salt water through special glands, she said. In addition, there was evidence that female crocodiles can store sperm for up to a couple of years.

The scientists' evidence showed that a single lineage was established in the New World and then diversified into the current four Americas-based species.

‘Many females could have made it and not successfully reproduced,' Dr Hekkala said.