The DNA sample that links their animal specimens to human DNA. All they've found are monkeys. A completely different species.
These fossils don't come with DNA, they are so old it has completely degraded. No dinosaur DNA has been found for the same reason (so can we be sure they were reptiles?)
And they are not monkey skulls. A brief search on google images for "monkey skull" and "Australopithecus skull" makes that very clear.