By Marc LallanillaLiveScienceBirds do it, bees do it — but how did 3-ton dinosaurs with sharp, pointed spikes on their backs and tails get it on?Very carefully, say some researchers, who believe mounting a female from behind would have proved deadly for the males of dinosaurs like Stegosaurus."The females could not raise their tails, because the bones at the top end were fused," Brian Switek, a di...