Saltwater croc's genetic linkage map made

SYDNEY, July 28 (UPI) -- Australian researchers have created the first genetic linkage map for the giant saltwater crocodile, aiding in its genetic sequencing, the researchers said.

"The crocodile is a very charismatic organism, but with surprisingly very little genetic or genomic resources available prior to this map," University of Sydney genomics researcher Lee Miles said.

The research will also help in understanding the molecular evolution of reptilian and other genomes of egg-laying animals, including mammals and birds, Miles said.

His doctoral research, conducted with the Darwin Crocodile Farm in Australia's Northern Territory and the University of Georgia, was published in the open-access journal BMC Genomics.

The saltwater, or estuarine, crocodile is the largest of all living "crocodilians," an order of large reptiles that appeared about 84 million years ago in the late Cretaceous Period.

They are the closest living relatives of birds, with the two groups being the only known survivors of a group of reptiles that developed two holes in each side of their skulls about 300 million years ago.

The Cretaceous Period ended with one of the earth's largest mass extinctions, when many species, including the dinosaurs, disappeared.