Re-Assessment: Rex vs. Spino

@Godzillasaurus - I wasn't actually part of the group that proclaimed these topics dead; I did propose an alternative forum since it was causing some trouble.  However since this is my own thread and it is older, I figured it wouldn't be a problem. Please feel free to give your thoughts on the matter!

@Spinosuchus - Most animals do not develop body parts that hinder their movement.  If you are a believer of evolution/survival of the fittest, logically Spinosaurus would, over time, develop a spine that was in some way beneficial to its movement.  If the spine was a hinderance, it would have evolved out. If you are a believer in species adaptation, like I am, you would most likely believe that the sail would have adapted to be beneficial - not necessarily stream-lined, but not a hinderance. Seperate parts of an animal do not usually contrast in the way they affect an animal.

My original intent was to argue that Rex and Spino are evenly matched. I assume you are arguing Rex would win in a fight? 

@Carnosaur - Interesting speculation. I would respond that Dimetrodon's closer, thinner vertebrae supported a slimmer sail, while Spinosaurus' thicker, wider-spaced vertabrae supported a thicker, less fragile sail.

@Carnosaur, actually, its rostrum wa not at all ideal for ripping and tearing. Its teeth weren't either. This animal was only adapted to grip, that is it. To have a snout really efficient at tearing, it would need to be either deepened or broadened (or in some cases, both. Such as tyrannosaurus). Spinosaurus has neither of these traits. Of course tooth shape isn't THAT great of an indicator here, as modern crocodilians too utilize torsion to feed, but broad-snouted species have, well widened snouts that can withstand that much pressure. Spinosaurus' snout, while certainly very strong, could not do this.

Also, the fish that spinosaurus took, while probably huge, were probably more in the 10-15 foot range at most for a common dietary item. A 20 footer like mawsonia, at least according to this size estimate, would probably be too much as a common food item (because remember, its snout was designed for tackling smaller animals overall, so one only a little bit smaller than its maximum size at around 50-55 feet in length or so would be ridiculous):

Mawsonia is a definite possibility (as spino was evolved to hunt things considerably smaller than itself), but I for one do not believe that it would have been a staple in favor of smaller and weaker fish. But I agree for the most part

@Dinosaur.Fanatic, either the sail (actually more-so of a muscular ridge) was beneficial or it wasn't. Based on its shape and overall positioning, it would do no more than provide simple "support" (for a lack of better words) in courtship (display), thermoregulation, or indimidation. It was not designed as a hinderance, but nonetheless it would be one if the creature was adapted to "chase down" larger terrestrial prey like in more typical theropod genera (ie. allosaurus or tyrannosaurus, as a basic example), but it obviously was not designed to do that. Furthermore, it would likely not be hunting fish this way either; most likely, spinosaurids would hunt with a simple "ambush" technique (all my theory), as their legs were not the longest and most powerful proportionally and the enlarged spinal column would likely prohibit this. Simply, spinosaurus is not going to be chasing down prey (regardless of whether it was terrestrial or aquatic), and would instead catch prey with quick, moderately powerful, penetration as opposed to what you would expect from more typical theropods.

And no, I do not believe the two were evenly-matched. There are so many problems with this idea; tyrannosaurus was downright the more heavily-built of the two and was, simply, far better designed for fighting and hunting large terrestrial creatures. At parity, the tyrannosaurus would dominate. The only real advantage in this case that the other has is its size advantage

i said its teeth were; not it's rostrum. That thing was quite resistant to lateral forces acting on it though, which would be perfect for hauling writhing fish out of the water.

I firmly agree that its rostrum was in fact probably very strong, and it is certainly evident when you examine it intensely (it was particularly dense and solid by theropod standards, at least when examining the size and presence of pockets within the skull; AKA fenestrae). Its strength would be much needed when grasping such powerful fish that were most probably the majority of its overall diet.

But I must say that its dentition as well was not ideal for ripping or tearing either; its morphology was similar to that of modern crocodilians in that it was round in cross-section as opposed to more oval and narrow. It has been theorized that it could have killed with violent head-shaking (ripping apart the prey animal in the process), but this has been jossed by rostral-strength studies