They are now thought to represent a stage soon after the transition between Australopithecus and Homo erectus , and have been dated at 1.8 million years before the present , according to the leader of the project , David Lordkipanidze . They are now thought not to be a separate species , but to represent a stage soon after the transition between Australopithecus and Homo erectus , and have been dated at 1.8 million years before the present , according to the leader of the project , David Lordkipanidze .