Watching a snake swallow its prey whole is an awesome experience.
Snakes feed like no other animal, thanks to their amazingly stretchable jaws.
But how this flexible jaw evolved from the inflexible jaws of snakes' lizard ancestors has posed a puzzle up to now. Now an intermediate stage in the evolution of a stretchable jaw has at last been identified in the extinct mosasaurs, fossil lizard cousins of present-day snakes, by Michael S.Y. Lee from the University of Queensland and colleagues. But they retained the immobile upper jaw typical of a lizard. Snakes evolved from lizard-like ancestors, losing their legs in the process and acquiring many more vertebrae in their backbone. They also acquired a quite new way of feeding, developing highly mobile and extensible jaws that can spread right round an item of prey and draw it down into the throat.