Dinosaur mating......the nuts and bolts

[andrewsaurus rex]

I would like to have a rousing discussion on the mechanics of how various dinosaurs mated.  I find many illustrations of theorized mating positions are too 'mammal oriented' in that the often show some form of modified 'doggy style' mating that most extant mammals use.

Problem is of course the genitals of mammals point in a different direction to those of reptiles and birds.  With mammals, the female's vagina more or less points backwards, while the male's penis more or less points forwards.  So mating from the rear is a fairly simple matter of 'plug and play'.

With reptiles and birds, the cloacae more or less point downward in both sexes and so it's much trickier to get them to connect.  Elaborate twisting and contortions of body and tail (where applicable) are needed to reach the end goal.  For small reptiles, lizards and birds it's not overly difficult and they have gotten very good at it.  But how can we imagine that huge multi ton dinosaurs performed these elaborate couplings?

It's a pretty safe bet that male dinosaurs had a penis that protruded out of their cloaca.  While most modern birds do not have penises, that is the evolved state and more ancestral birds do have penises (eg ostrich, ducks etc).  So the loss of the penis being the evolved state, it is fairly certain that virtually all male dinosaurs had them.  Great, so that will help things along somewhat.

But how big could the penis be?  The cloacae of male and female would still have to be positioned relatively very close together for the male to be able to aim and score a direct hit in the female's cloaca.  How did two 7 ton T-Rex's get everything positioned correctly, especially when they are bi-pedal and thus less stable than four legged animals?  What about stegosaurs with their backs full of plates and spikes....how did the males mount the females without impaling themselves?   And ankylosaurs with their massive armour....how could they have possibly performed the required 'cloacal kiss'?  And what about a pair of 50 ton titanosaurs?

This is where the rousing part of the discussion begins, I hope.  I have done some reading on this subject and have some ideas on how dinosaurs did the deed, which i'll add to this thread as time permits.  But i'd like to hear the ideas and thoughts of others.....

[Sarapaurolophus]

I would like to have a rousing discussion on the mechanics of how various dinosaurs mated.

Goodnight everybody!

(Sorry, I have nothing to add but dumb jokes)

[Lanthanotus]

I would like to have a rousing discussion on the mechanics of how various dinosaurs mated.

Goodnight everybody!

(Sorry, I have nothing to add but dumb jokes)

Indeed a good one

As for the question.... even dedicated books leave most of the details open, unfortunately. However, while mammals may be very different in a lot of regards from dinosaurs, the biggest existing animals are from the group of mammals and their organs may give us some lead here. In very big mammals as elephants and whales, the male genital is more or less "self guiding", its sensory system developed in a way, that it can "feel" its way towards the female vagina. With the help of cavernous bodies the genitals can reach great sizes (even outside the water where buoyancy surely facilitates the whole process), so maybe dinosaurs used some kind of combination of the everting hemipenes as they are in lizards and the spongy body and blood assisted penis of mammals to cover the distances.

That still sure leaves out the question of the positioning of the animas`bodies, but maybe the everting genitals reached sizes of 3 or 4 meteres as in whales and the animals did not really need to be acrobatic, but just standing with their hinds near to each other and the male penis everted side ways (as in lizards, where the male "chooses" its prefereed side) making its way on its own? Not very adventurous, romantic or cuddly, but.... possible?

[andrewsaurus rex]

Interesting......I wasn't aware of that about whales.  That would certainly facilitate mating in dinosaurs for sure and could be nature's go to method for huge animals, perhaps.  I read one source that said T Rex may have had a penis up to 12 feet long, which seemed unmanageable to me, but in light of what you just wrote, it seems a lot more plausible now.  This is the kind of info I was hoping for when I began this thread.  More to come I hope.

ps i'm glad my little opening quip didn't go unnoticed.  I thought it may be too subtle but clearly not. Sharp bunch of members here.  Love it.

[Halichoeres]

There are some videos of tapirs mating on YouTube. There's definitely some self-guiding going on there, although it's a little hit-or-miss. But I guess it only needs to hit once.

I would like to have a rousing discussion on the mechanics of how various dinosaurs mated.

Goodnight everybody!

(Sorry, I have nothing to add but dumb jokes)

This was also my first thought 

[Dusty Wren]

With mammals, the female's vagina more or less points backwards, while the male's penis more or less points forwards.  So mating from the rear is a fairly simple matter of 'plug and play'.

Tell that to spotted hyenas

But yeah, I agree with @Lanthanotus. I always assumed that dinosaurs would have had a similar set up to whales. And long penises in dinos seem pretty reasonable, too, since I think the current record-holder for longest penis among vertebrates is a duck.

[Papi-Anon]

I've always imagined that for at least stegosaurs and their relatives they might have mated facing opposite directions pressing their ends together (cloaca to cloaca) to avoid messing with the plates. Not fully mirroring the other but sort of side-by-side with tails parallel to one another more or less. This position could theoretically also give the pair 360-degree vantage of their environment in case a stalking predator may try to attack during the moment of defenselessness.

On a funny note, such a strategy reminds me of Mel Brooks's 'The 2,000 Year Old Man' where he explained that marriage began as a means of watching one another's back, with the couple standing back-to-back as they moved about so as not to be attacked by lions or bandits, and only turning around to look at each other on high ground.

[andrewsaurus rex]

yes ducks have the longest penises relative to body size of any animal on earth.  They are sort of cork screw shaped and thin but remarkably long.  Mating is also apparently a painful experience for the female.

One theory I saw for stegosaurs was that the female would lie on her side and the male would squat over her cloaca on an angle to her body.  This would bring the cloacae very close together and avoid unwanted impalements on spikes.  It's an interesting idea and I can see a lot of dinosaurs perhaps using this method as it is very stable, somewhat intimate, doesn't require multi-meter long penises and safe.  I can't see it working for ankylosaurs however as they couldn't really lie on their side and if a sauropod were to lie on her side, I don't know that she'd be able to get up again.  But for many species, the female lying on her side position would be a good one.  Problem with this idea is that there are no modern day analogues for this position among birds or reptiles, that I know of.  Not sure if that matters, but it bugs me.

[stargatedalek]

All of this warrants establishing that duck anatomy is more extreme than whatever their ancestral condition is, as its evolution has been fuelled by their violent nature.

One of the older True Facts video covers ducks and their horrifying anatomy in detail. Warning these videos are not for children, and earlier ones were even less tame.

Spoiler

https://www.youtube.com/watch?v=6k01DIVDJlY

[close]

If you're starting to hate ducks, don't fret! Mergansers and geese are not simply consensual but arguably actively romantic and treat their partners very well.

[Faelrin]

Definitely an interesting topic and one I'm curious about as well, because well without it, these magnificent creatures wouldn't have been able to last as long as they have, or diversify as much as they did (I suppose that goes for any living being, with some exceptions).

It reminds me of that mating Diplodocus segment in the Time of the Titans episode of WWD. In fact I think that's the only time I can actually recall seeing a documentary covering this topic in such detail (maybe in Planet Dinosaur as well?), though I wonder how plausible that is now based on the discussion here.

Regarding the discussion of the ducks, it definitely brought up memories of that (NSFW) True Facts video that was shared by @stargatedalek , which makes me very glad that I am not a duck, though I do also wonder if some non-avian dinosaurs possibly had something similar going on if needed.

I guess this whole thing has also made me curious about how modern crocodilians do it too (if I vaguely recall correctly it's done in the water?), but that might not be typical to most dinosaurs anyhow.

Edit: I guess while this is probably the trickier side of things (aside from using possible living analogues), since without exceptional evidence we have no way to observe behavior in these long extinct animals, but I am also curious about courtships, pairing, etc as well. I know there's definitely numerous birds that have wild displays (birds of paradise), or mate for life (such as some raptors and songbirds).

[andrewsaurus rex]

I strongly suspect that dinosaur courtship rituals were diverse and dramatic, just like birds.  Maybe not for the non-avian dinosaurs as much.

As far as crocodile mating, it is apparently always done in the water after a land based courtship.  The water would be very helpful to mating, as the buoyancy and 3 dimensional nature of it would give a lot of options for bringing the cloacae together...perhaps even some kind of 3 dimensional missionary position.  And that's good, because crocodile penises are only about 4 inches long.  I've never seen a picture of crocodiles actually mating, so if anyone can point me to one i'd appreciate it.

However, I don't see how crocodile mating translates well to most dinosaurs.....maybe for spinosaurs?

I've also looked at how komodo dragons mate and tried to draw from that for dinosaurs.  They mate like most lizards and reptiles with the male on top, at an angle to the female and they twist and contort their tails, so their cloacae get close together.

One of the biggest problems I see with dino mating is those big tails that most have.  They are huge, thick, often not terribly flexible and really in the way..

[Lanthanotus]

Crocodilians (at least our modern ones) mate like lizards, but they do not have hemipenes, but just single organs.
I think the main problem in a lot of dinosaurs was their gargantuan size in general, because despite what most TV shows would suggest, those sizes and masses have a great influence on the general mobility. However, we have barely any modern comparisons. We "know" at least some very large sauropods could get in a tripod stance, but for example if a grown T. rex could stand on one leg for a few seconds for positioning itself for mating, is not known ( I say this, because of its mass it is pretty sure it could not run in the way that both feet are off ground at a moment or jump).

[andrewsaurus rex]

i was looking at my big Jurassic world Brachiosaurus and wondering again about mating.   I don't see a Brachiosaurus male being able to rear up and mount a female.  He'd be standing on two legs and unstable and she would be supporting a lot of extra weight.  And I don't see her lying down in any fashion, during mating, as she may not be able to get back up.

What about this?  What if the couple stood side by side and pressed their tails together.  The male's penis, self guiding, comes out of his cloaca and charts a U shaped course into the female's cloaca.  The distance would not be all that great and both animals are very stable.  There could even be a great deal of intimacy in this position.

Thoughts?