In my last post, I wrote about the biomechanical issue surrounding sexual activity amongst the saurpod dinosaurs (the really big, long necked ones) and those with spiny backs. In today’s post, I’s like to consider some of the solutions which have been offered.
Of those who have considered the problem, as we have seen, many initially suggested that they did it doggie-style, but copulating in this position, as we saw last time presents all manner of biomechanical and hydraulic problems.
Some animals, particularly birds, do not engage in penetrative sex, but rather perform what is anthropomorphically known as a cloacal kiss: that is to say, no penis is, strictly speaking, necessary, and the sperm is exchanged during a brief period at the climax – as it were – of the mating ritual. The big problem here is trying to work out how Mr. Dino manage to get his cloaca anywhere near that of Mrs. Dino, since they both had great big fat and rather stiff tails? It has even been suggested that perhaps they did it face-to-face, with one of them lying down, but this seems rather unlikely to me as these were such big animals that even the act of lying down would have presented massive problems (no pun intended), and this before we even take into account the fact that the dinosaur underneath would have had to bear at least some portion of the weight of the dinosaur on top, and this would likely have been a crushing burden, literally, particularly when you consider that they would now be bearing this weight on their ribs and other parts of their skeletons not at all designed to bear weight.
As we saw in the last post, some scientists have suggested that the large sauropod dinosaurs may have mated in water, but there are issues with this too. Water pressure increases by roughly one atmosphere for every 10 metres of depth, so a sauropod dinosaur, with its body say 15 metres under water would not be able to breathe at all, as its chest and diaphragm muscles would not be strong enough to overcome the hydrostatic pressure at that depth.
This is one of the reasons (as I noted in the previous post) that snorkel tubes for humans are never longer than about 45 cm; go any deeper into the water, and the human would not be able to draw any air into its lungs anyway because its diaphragm & chest muscles are not powerful enough (if you’d like to calculate the water pressure at any given depth, please go to this site and play around with the converter you will find there: http://www.calctool.org/CALC/other/games/depth_press).
There’s also another reason why snorkel tubes are of limited length. It has to do with what’s called dead air space: ‘when you breathe in normally you take air into your lungs where it is utilized. Respiration only takes place in the lungs but there are air spaces such as the sinus cavities, mouth, and windpipe that also get filled with air upon inhalation. The air in these areas is not being metabolized or used. This, in essence, is “dead air”. Your lungs are able to bring enough air in past these dead air spaces to get the supply that they need in order to function. Add a snorkel into the picture and you have lengthened the dead air space. Air is there but the body cannot use it. Now, when you exhale a portion of what you are exhaling is carbon dioxide which your body cannot use. Your exhalation goes out the same way it comes in which mean it travels through the same dead air spaces that were along the path during your inhalation. Consequently, as you exhale, you end up filling the dead air space with oxygen-depleted or carbon dioxide enriched air. So, when you take in your next breath, you first have to pull in all the stale air in the dead air space before you can start to bring fresh air into your lungs. Under normal circumstances, the lungs of any animal would obviously be big enough to take in that as well as getting enough good air to still function properly (otherwise the species would have died from oxygen starvation). Adding a snorkel, through which you inhale and exhale, means that you will be inhaling even more of your exhalations. So, if you made the tube longer then you would be re-breathing more of what you exhaled which is not a good thing. (From :http://www.snorkelingonline.com/blog/why-are-the-tubes-onsnorkels-so-short/ mutatis mutandis).
Now this actually poses a bit of a conundrum for sauropod physiologists: with their enormously long necks, sauropds would have a lot more dead air to get through before their lungs managed to get any fresh air. We do not yet really know how they managed this, but presumably they had enormous lungs, which then would have meant less room in their body cavity for the other organs. I already noted in my previous post that if these sauropod dinosaurs were to have held their necks up like giraffes and even more so if they were to do it doggie style, they would have had to have enormous hearts, and there simply isn’t enough room in there for both a massive heart and massive lungs, which is another reason why I do not think doggie-style was the way sauropods did it: there was simply not enough room in their bodies to fit the large hearts and lungs which would have been necessary to do it this way.
Another idea has been that they did it bum to bum, achieving the cloacal kiss by twisting their rumps and raising their tails slightly, whilst perhaps also lowering their heads,. This is a possibility I suppose, but given the thickness of their tails, I must admit that I still find this hard to imagine.
Some people have even suggested that dinosaurs did it like amphibians and fish do, via external fertilisation, where the female first lays her eggs, then the male deposits his sperm on them once they are in the nest. The problem with this scenario is that dinosaurs, at least as far as we can tell, laid hard-shelled eggs, which would most likely have been impervious to penetration by sperm. Perhaps they laid soft-shelled eggs which hardened once they had been fertilised. This is possible I suppose, and it would certainly solve the prickly problem posed by all the spiny-backed dinosuars I discussed last time, but it is unlikely that we shall ever find hard evidence of this, as soft tissue fossilises so very, very rarely. Still, given that the clade has proven to be so idiosyncratic in so many other ways (for example they may not have been reptiles at all, but rather have had physiologies which were more avian, they may have been warmblooded, and were most likely, at least in some cases partially feathered rather than being completely scaly), perhaps in this one too, dinosaurs had a particularly dinosaurian way of reproduction. We simply do not know. Whatever the case may be however, I really doubt that they experienced the drawn out ecstatic bliss which pigs are supposed to enjoy during sexual congress: poor guys indeed!