Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales. Many species of snakes have skulls with many more joints than their lizard ancestors, enabling them to swallow prey much larger than their heads with their highly mobile jaws. To accommodate their narrow bodies, snakes' paired organs (such as kidneys) appear one in front of the other instead of side by side, and most have only one functional lung. Some species retain a pelvic girdle with a pair of vestigial claws on either side of the cloaca.
Researchers have discovered what they believe to be a grandfather of snakes, which descended from terrestrial rather than marine ancestors. “It’s the missing-link snake between snakes and lizards,” says Nicholas Longrich, a postdoctoral fellow in the geology and geophysics department at Yale University and the lead author of a paper published in the journal Nature. [...]