The Desiccating Environment of the Extreme Environment

Scientists have recovered mummies from the bottom of three volcanoes. They used radiocarbon dating to see if there's a match or difference in the timing of when those mummies became mummies. And then, also to do the DNA sequencing. The question they set up here is given that it's so extreme, as we've been sort of glimpsing at here, how did those mice get there in the first place?