An alternative possibility is that Homo derived directly from Ardipithecus , with an as yet undiscovered link connecting Ardipithecus and Homo habilis existing in parallel to the Australopithecines in the period 4 to 2.5 million years ago . An alternative possibility is the derivation of Homo directly from Ardipithecus with an as yet undiscovered link connecting Ardipithecus and Homo habilis existing in parallel to the Australopithecines in the period 4 to 2.5 million years ago .