Actually, to be precise,
dinosaurs didn't
piss. Like
crocodiles,
birds, and other
reptiles, they leached all the
water possible out of their waste and excreted only
uric acid (as opposed to
urea, the familiar
mammalian form). Uric acid is the white stuff that surrounds the
black stuff in
bird shit.
Dinosaurs probably excreted in a similar manner, depositing their minimal uric acid at the same time as their
feces. Some lucky dinosaur feces would go on to become
coprolites.
Pseudo_Intellectual informs me the term is slang for
petroleum. Heh. 'Course,
petroleum comes from
plant matter, not dinosaurs.