Via the Smithsonian Magazine:

I have been sitting here with two Stegosaurus models for 20 minutes now, and I just can’t figure it out. How did these dinosaurs—bristling with spikes and plates—go about making more dinosaurs without skewering each other?…Hundreds of dinosaur species have been discovered (and many more have yet to be found); they lived, loved, and lost over the course of more than 150 million years. There may have been as many courtship rituals as there were species of dinosaur. In recent years, paleontologists moved out of the realm of pure speculation and begun to piece together the rich reproductive lives of some of these animals….