These things weigh 220 tons](http://www.gavinrymill.com/dinosaurs/largest-dinosaur-ever.html)! How could they mount and do the nasty without killing themselves?
The mating was only PART of the problem!
The tough part was finding a restaruant large enough to take your dino date to, first…and Dancing… well!
Actually they probably “humped” pretty much like modern lizards do, although I have no site for this…
FML
Well if they weigh about the same, it wouldn’t hurt too much, right? I’d be more worried about whatever small animals got in the way.
It’s possible that they didn’t mount. Maybe the male had a very long, flexible penis. After all, that’s the situation in whales, which don’t mount either.
Try reading this in Jack Benny’s voice and you’ll giggle all night.
Maybe they mated in water?
You wouldn’t think that elephants could mate, either, to look at them. How could the big ungainly male ever get up there? But they do.
Didn’t they lay eggs? Or am I missing the funny?
Assuming you’re serious (and maybe, coming from the city of Detroit, you are):
Even animals that lay eggs have to have intercourse beforehand for the eggs to be fertile.
Hen chickens lay an egg every day (generally), but most of them do not hatch into a live chick, because they were never fertilized. They just end up in a carton of eggs at a grocery store.
I realize that the egg is unfertilized in the hen and other aviary animals, but is the intercourse as, umm, vigorous, as in mammals?
Also, don’t some egg laying species have ways to fertilize the egg without intercourse?
Most birds don’t have penises, but mate by bringing the cloacas together. Ostriches and other large flightless birds, and waterfowl such as ducks, do have penises. Absence of the penis in most birds is probably related to weight conservation for flight.
The closest living relatives of birds are crocodilians, which do have penises, as do all other “reptiles” except the tuatara.
Based on this, it’s pretty likely that dinosaurs had penises.
All terrestrial vertebrates (“reptiles,” birds, and mammals) have internal fertilization and have some kind of “intercourse,” whether with a penis or by bringing cloacas together.
There are other more exotic ways of achieving internal fertilization without “intercourse,” such as the male depositing a sperm packet or spermatophore which the female then picks up, but it’s very unlikely dinosaurs resorted to anything like that.
Thanks Colibri!
I’ve always wanted to do this…
Short answer: No penis; Kissing cloacas. Maybe.
Another possibility is that the huge dinos mated while they where still small enough, then grew to gargantuan sizes after their reproductive years.
ETA: Gah! Damn you, HazelNutCoffee! 
Heh. Sorry, dude. I just googled “how did dinosaurs have sex?” and the first link was the SD. I have to say I was disappointed - I was expecting some weird kinky dinosaur porn site.
This. It’s hilarious, psychological, disturbing, and hilarious all at the same time.
How would this evolve? I can’t imagine how this could be advantageous and be selected for.
(I recognize that this concept came from Cecil’s cite.)
(See the Cake Wreck thread in CS, whence the link came.)
I’m no expert in evolution, paleontology, or any of the sciences really (obviously), so I can’t say. I do know that features can evolve, so long as it’s not a detriment to its survival.