Researchers looked back at more than 70 million years of snake evolution to learn more about the legless critters.

A team of scientists looked at the fossilized remains of four snake fossils from between 140 and 167 million years ago, the University of Alberta reported. The findings could help change the way researchers look at how or when modern snakes developed.

"The study explores the idea that evolution within the group called 'snakes' is much more complex than previously thought," said University of Alberta professor Michael Caldwell, professor in the Faculty of Science and lead author of the study published today in Nature Communications.

The oldest-known snake, dubbed Eophis underwoodi, resided in an area near Kirtlington in Southern England. This new study shows the sudden appearance of snakes about 100 million years ago indicates a gap in the fossil record, as opposed to an "explosive radiation of early snakes."  Snakes from between 90 and 100 million years ago that still possessed small rear limbs from West Bank, Lebanon and Argentina have now been documented.

The researchers noted a number of fossilized skulls that were previously associated with other non-snake lizard remains may actually represent the earliest days of the reign of snakes.

"Based on the new evidence and through comparison to living legless lizards that are not snakes, the paper explores the novel idea that the evolution of the characteristic snake skull and its parts appeared long before snakes lost their legs," Caldwell said.

The researcher concluded the distribution of these very early snakes suggest there are even older snake fossils out there waiting to be discovered by science.