Thats whats the hump theory says:
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As you see, its a massive structure. Not some skinny thin sail.
I definitely see your point as far as the spines being different from dimetrodon but still as I said they found proof of large blood vessels in the spines,suggesting some form of thermo regulation. It was German paleontologist Ernst Stromer in 1915 who found the first Spino and speculated the hump theory. The remains where lost during World War II though unfortunately. By the way am I being ignored because I'm the only one actually citing stuff as well as suggesting a practical logical function for the sail theory?lol!
The most recent theory is the sail theory and as I said it was given rise to by the discovery of large blood vessels in the spines. Blood vessels suggest either some form of thermoregulation or a muscle group, definitely not a fat deposit. I'm also the only one to suggest a practical function of a sail rather than a hump.
Think about it if the hump contained muscle what was it's function? As mentioned earlier the Bison spines where behind the neck at the shoulders. They helped support the neck muscle and create a foundation for plowing through things and possibly for courtship combat between two males. While in Spino they're highest at the center of the back which would support what if they where covered in muscle? In no way would it help support the neck for swimming as you suggested earlier Darius. You've yet in my opinion to explain a possible function for a hump. And with all animals function usually denotes form.
Again I think for perhaps the third time I offer up a sail form used for display for courtship and as thermoregulation. The large blood vessels would help with the transfer of energy or dissapation of it, in this case heat. I went through a long explanation before explaining how it would work and why. I'll try here again as it seems to have been ignored and not rebutted. It's simple more surface area means something can be heated or cooled at a faster rate. Spinosaurus is the largest carnivore and as such would benefit from a sail whether he was endo or ectothermic. Dwarfing T rex by 2 tons it would take a significant amount of energy to move such an animal. The larger the animal the more exertion required for it's metabolism the more heat produced during physical activity. So if Spino's where ectothermic they would use the sail to absorb the heat from the sun and speed up their metabolism much like a basking lizard. Except due to their large size perhaps they needed the aid of the sail to increase the efficiency of their basking. If they where endothermic then the sail could conversely be used to cool the body. Same principal just the sail would be turned into the wind and speed up the cooling effect if the Spino retreated to the shade. Also the sail would be helpful in the water much like a dorsal fin. Spino's where supposedly just as comfortable on land as in the water, so a sail would also serve a function there.
Also one more point going back to the Basilisk comparison. If you look at the structure of the Basilisk's sail it's actually exactly like Spinosaurs. Look up their skeleton, the placement of the spines is exactly like Spino's in placement and shape. Their spines are short and broad. The Basilisk uses it for 2 things balance when running on water(hence them sometimes being called the Jesus lizard) and for added agility when swimming in the water. The sail adds extra propulsion and allows for quick direction changes. If you've ever seen a Basilisk swim you'd see exactly what I'm talking about. As you suggested Darius, perhaps Spino's fed on fish and in that case the added agility would come in handy for catching fish. That's why I'm leaning toward them having sails.
Can I ask what function you think the hump would have played?
