Fellow Prehistory Nerds - I have a crazy-ass theory about Spinosaurus

[bigfatcarp93]

Okay, so.

Spinosaurus.

The pussy ***** of large theropods.

What I of course mean, is that most people assume that unlike it's fellow large theros, this ridiculous animal was likely a piscivore; i.e. it ate fish, rather then hunting large animals. This is pretty apparent in the way it was built, with thin, crocodilian jaws that likely lacked the crushing power to get through the thick muscle and bone of a large herbivore, and fishhook-like claws that lacked the cutting edge they needed to slice through the thick, leathery hide of a dinosaur.

These adaptations were, of course, perfect for catching fish, as were it's raised nostrils and other such semi-aquatic features. So it makes perfect sense that Spinosaurus fed by gorging itself on the many large fish that lived in the same time and place (The area that is now the Sahara Desert, 100 million years ago) rather then hunting big animals like a proper carnivore. Clearly, a wuss.

But I believe it was even worse then that.

Not only do I believe ol' gator-head wasn't a predator - I think it was prey.

I mean, imagine it: you're a Carcharodontosaurus. You are a lean, mean killing machine (And probably have a pack - I mean, there were sauropods around there, and something must have been hunting them, yes?). So, you're out prowling the swamps with your homies, and you see this other dino, some prick with a big dumb fin on his back. He's pretty big, but when you get a look at him, he doesn't look that tough. He's sitting there picking some fish out of his tiny, conical teeth that don't look like they could kill a baby Nigersaur, with the most absurd looking claws you've ever seen, and he has that big sail on his back.

Thing is, that sail would have been a huge liability. Long, thin neural spines that fuse directly into the backbone, so breaking them could cause severe, maybe irreparable spinal damage. And, if we're right about the sail being full of blood vessels, breaking it should also cause Spiny to bleed out, very fast.

So, yeah, you're pretty sure you and your posse can take him. Why wouldn't you go eat him? Well, the answer is that YOU WOULD. Seriously, other large theropods around there would have had no reason to fear Spinosaurus, no reason to compete with it for territory, and NO REASON NOT TO ACTIVELY HUNT, KILL AND EAT IT.

But, it goes even farther then that, and actually gets kind of cool:

Spoiler

You see, realizing this got me thinking about how Finny would protect itself from predation. And at this point, I started to go into the really weird side of my theory: what if Spinosaurus existed symbiotically with herbivores? A few Spinos living with a large herd of sauropods or iguanodonts, watching each other's backs, maybe with alternating senses; say, a herd of Ouranosaurs with very good senses of smell, backed by a few of the tall Spinos with their big, craning necks to keep an eye on the horizon and see over the treetops.

And THAT got me thinking about the purpose of the sails.

We don't really know what the sails were for; both Spinosaurus and Ouranosaurus carried them, but... why? Thermoregulation? For WARM-BLOODED ANIMALS? In AFRICA? A form of display makes sense, but it does seem like an odd coincidence, no, these two COMPLETELY UNRELATED Dinosaur genera developing these sails AT THE SAME TIME?

And so I though... what if it's an inter-herd communication thing? Like, if a member of either species spots or smells trouble, they flare up the sail another color, and alert the rest?

The next part really gets pretty farfetched, but I even had an idea that the two may have helped each other gather food: maybe Ouranos splashed around in the river to scare up fish, and maybe Spinos used their impressive height and hooked claws to pull down high tree branches.

So... thoughts?

 

[JoJo]

Hm, what I wonder though is that even if Spinosaurus was weaker than other large theropods like Carcharodontosaurus, that still taking it on might be too high a risk just for food. I mean, if we look at it size-wise:

It's a pretty hefty beast. There's a high chance that even the victor of an encounter with one would come away with some nasty claw or bite wounds, with the risk of infection I imagine the other large theropods would rather target smaller, less dangerous herbivores.

 

[bigfatcarp93]

Hm, what I wonder though is that even if Spinosaurus was weaker than other large theropods like Carcharodontosaurus, that still taking it on might be too high a risk just for food. I mean, if we look at it size-wise:

It's a pretty hefty beast. There's a high chance that even the victor of an encounter with one would come away with some nasty claw or bite wounds, with the risk of infection I imagine the other large theropods would rather target smaller, less dangerous herbivores.

But as I said, such predators would probably already hunt in packs to take down Sauropods, and I'm sure a Paralatitan would be considerably more dangerous then a Spino.

 

[JoJo]

But as I said, such predators would probably already hunt in packs to take down Sauropods, and I'm sure a Paralatitan would be considerably more dangerous then a Spino.

Being in a pack wouldn't protect them from potential injures while taking down the Spino though, I mean if you think about it in a modern day context I can't think of any examples of top predators regularly preying on other top predators of similar size. Predators aren't great to eat either generally, they tend to have high concentrations of toxins from being high in the food chain. It's possible, but I don't think it's likely.

 

[bigfatcarp93]

But as I said, such predators would probably already hunt in packs to take down Sauropods, and I'm sure a Paralatitan would be considerably more dangerous then a Spino.

Being in a pack wouldn't protect them from potential injures while taking down the Spino though, I mean if you think about it in a modern day context I can't think of any examples of top predators regularly preying on other top predators of similar size. Predators aren't great to eat either generally, they tend to have high concentrations of toxins from being high in the food chain. It's possible, but I don't think it's likely.

Fair enough. I still think a big sauropod would be more dangerous when it can freaking crush you with it's 60-odd-ton mass, but you have a point about the other thing.

Well, it was fun food for thought.

 

[Drops a Sweet Katana]

While I don't think that a gang of Carcharodontosaurus taking a Spinosaurus down is out of the question, it seems unlikely that it would be prey. It's larger, albeit lighter, than Carcharodontosaurus with some pretty formidable defences that, even if they didn't kill, would inflict some pretty grievous wounds which could become infected and leave the Carcharodontosaurus unable to hunt effectively. This would make Spinosaurus a very high risk prey item. This would be fine, sauropods aren't exactly easy targets either, however that's a lot of risk to put yourself in for prey that is lighter than you and your usual saurpod prey which weighed about about 3 times that of Spinosaurus, meaning less meat in the end for you and your packmates than if you put in the same amount of effort to hunt something like a Paralititan. Add to this the fact that the two species filled different niches with Carcharodontosaurus being an apex predator and Spinosaurus being a piscovore that would only occasionally hunt larger prey, although likely nothing larger than maybe Ouranosaurus. This would exclude the notion that Carcharodontosaurus would be hunting Spinosaurus to kill off competitors. The only time I see this occurring is in times of hardship where either animal's usual prey items are not available.

The second idea, while cool, seems very, VERY unlikely as Spinosaurus was a carnivore double the length and 10 TIMES the weight of Ouranosaurus. It could easily overpower and subdue an Ouranosaurus and, being a carnivore, it probably would given the chance.

 

[bigfatcarp93]

While I don't think that a gang of Carcharodontosaurus taking a Spinosaurus down is out of the question, it seems unlikely that it would be prey. It's larger, albeit lighter, than Carcharodontosaurus with some pretty formidable defences that, even if they didn't kill, would inflict some pretty grievous wounds which could become infected and leave the Carcharodontosaurus unable to hunt effectively. This would make Spinosaurus a very high risk prey item. This would be fine, sauropods aren't exactly easy targets either, however that's a lot of risk to put yourself in for prey that is lighter than you and your usual saurpod prey which weighed about about 3 times that of Spinosaurus, meaning less meat in the end for you and your packmates than if you put in the same amount of effort to hunt something like a Paralititan. Add to this the fact that the two species filled different niches with Carcharodontosaurus being an apex predator and Spinosaurus being a piscovore that would only occasionally hunt larger prey, although likely nothing larger than maybe Ouranosaurus. This would exclude the notion that Carcharodontosaurus would be hunting Spinosaurus to kill off competitors. The only time I see this occurring is in times of hardship where either animal's usual prey items are not available.

All good points.

The second idea, while cool, seems very, VERY unlikely as Spinosaurus was a carnivore double the length and 10 TIMES the weight of Ouranosaurus. It could easily overpower and subdue an Ouranosaurus and, being a carnivore, it probably would given the chance.

That's largely a behavioral question that I feel is harder to quantify. If such a symbiosis had started to develop with a less dangerous ancestor (Say, Suchomimus) then I think it's feasible that a Spino could very well have evolved to instinctually act peacefully towards Ouranos. Of course, it presupposes Finny occupying a prey niche, which you've all voiced some very convincing opposition to.

 

[Adventurer2626]

Interesting hypothesis. The idea had never occurred to me. As JoJo pointed out it is a high-risk game but not out of the realm of possibility during a famine. I'm sure predators have always will continue to turn on each other when game gets scarce. You do what you gotta do, but go after the weak ones first.