THEY have been dubbed the Red Deer Cave people and they are a big mystery.

Fossils of this previously unknown group of prehistoric humans, who lived as recently as 11,500 years ago, have been discovered in south-west China by a team including Melbourne researchers.

Red Deer Cave man... A highly unusual mix of archaic and modern features. Illustration: Peter Schouten

Their highly unusual mix of archaic and modern features raises the possibility they represent a new species of human.

Team co-leader Darren Curnoe, of the University of NSW, said the physical appearance of these extinct people was unique.