Carbon dating is only supposed to be accurate to about 40,000 years ago. They must be using some other method to date it, but I didn't see in the article where they say what method was used.
One of the major differences between the paleontologists and archaeologists is their opinion of shale and other mudstones. Paleontologists love the stuff, archaeologists hate it.
This page has a table of different dating methods that work on minerals and the time ranges to which they are accurate.