The article said that they were able to date using burned bone, and there is a photo of fire stained area. It also said the area had been protected by calcite, presumably deposited relatively soon after use by man. I wonder if any digging has been done under this calcite layer, or if they are still just studying the surface.
Since 176K is over three times the radiocarbon dating limit, I'd better read this in more detail to find out the method used. :')