A conservationist made a bizarre discovery when he disturbed a twig snake in an African forest - a new species of chameleon came out of its mouth.

Dr Andrew Marshall, from the University of York, was surveying monkeys in Tanzania's Magombera forest when he startled the snake, which spat out the tiny chameleon and fled.

Dr Marshall said: "I took photos and showed them to a local herpetologist, who instantly recognised that it was a new species."