"This is a terrifically important discovery because it shows, in a group of animals thought to be closely related to snakes, that forelimb reduction and trunk elongation were well underway before the onset of hindlimb reduction," said Cohn. "By uncovering the sequence of the morphological changes that occurred during evolution of a snake-like body plan, Palci and Caldwell's study provides important clues as to which developmental mechanisms could have been involved."
The researchers think this snake-like lizard was about 10 to 12 inches long, had a small head perched on an elongated neck, body and tail and relatively large and well-developed rear limbs. All bones of the forearm, including the hands and digits were not formed during development.
"For some oddball reason the forelimbs were lost before the rear limbs when you would think it would be the opposite," said Caldwell. "The front limbs would be useful for holding onto dinner or digging a hole but it must be developmentally easier to get rid of the forelimbs."
The most well known ancient fossil snakes also kept their hind limbs. Living lizards also show almost every variation in limb reduction from a perfectly formed back limb with no forelimb, or a spike for a forelimb and one or two toes on the rearlimb, to total limblessness. This degree of variation makes it very difficult to understand the pattern of evolutionary limb loss in these animals.
"This discovery is one more data point that might help us answer some questions and perhaps shed some light on the fin to limb transition, which is a key step in the evolution of land animals," said Caldwell. "It doesn't give us all the answers but it's a start."