The article sez “up to 360 million years ago”, Australia has some of the oldest surviving surface on Earth. 20 km is a pretty big rock, 360 million years ago would be during the Cambrian; the Permian is estimated to have started about 298 million years ago.
I knew that Cambrian was older, so decided to go to Wiki. It has an excellent graphic for earth history buffs. Unfortunately the graphic refused to print here, so below is the link. Maybe someone else knows how to make it print, it is a beauty. It shows that 360 mya was at the end of the Devonian and start of the Carboniferous. So that meteor strike probably did cause the significant break between these two.
http://en.wikipedia.org/wiki/Geologic_time_scale