This may be better asked as two questions; if so, I will edit.
The question is prompted by a section in Neanderthal Man: In Search of Lost Genomes by Svante Pääbo, who was the first to sequence Neanderthal (and Denisovan) DNA. Pääbo and his team had to work out techniques for sequencing nuclear DNA ten and more thousands of years old. They experimented with coprolites -- fossilized feces -- of the extinct American ground sloth.
The giant sloths had left behind large amounts of droppings, which archaeologists dressed up with the fancy name of coprolites. In fact, in some caves in places like Nevada, the entire floor, to some depth, is largely made up of old ground-sloth feces.
So, suppose one has to take shelter in a cave in Nevada: how would one distinguish an ordinary dirt floor from a floor formed of coprolites of the extinct American ground sloth? Are there any risks involved in taking shelter in any of the coprolite caves? (except for the possible ick factor)
[This sloth,] Mylodon, weighed about 1,000 kilograms (2,205 lb) and was about 3 m (9.8 ft) long from snout to tail tip