Spinosaurus Diet and Feeding

[Godzillasaurus]

To make this point clear, I decided to make a thread about it. It is a "remake" of my other spinosaurus thread which I deleted because it was so unclear and disorganized. But here we go. It should be a common knowledge fact that spinosaurus was in fact a piscivoruous animal (its diet was made up mostly by fish, as with all spinosaurids, which had similar defining characteristics); that is the bottom line. Unlike the majority of other large predatory theropods, it was not adapted for taking down large prey items (including the sauropods, large theropods, and large crocodylomorphs that it coexisted with). And yes, many people still consider it to have been a weakling because of such.

Here is the truth though, spinosaurus was a far cry different from the Indian gharial (which is the only modern crocodilian that feeds on almost exclusively fish in adulthood. Arguably the only truly gracile-snouted crocodilian) in terms of morphology. Its morphology clearly represents that of an animals that was designed for hunting large and powerful fish. For one we have its snout. We have a few complete rostra (upper jaws) to work with, but they are almost nearly complete. The simple fact of it is, they were not very gracile or fragile, contrary to what many believe. Its snout was unique because not only was it very slender but it was as well more-so of a solid structure, whereas the skulls of most other predatory theropods were larger multidimensionally and pneumatic. This structure, in terms of build, was more structurally sound for gripping than that of what some might consider to have been "far stronger than spinosaurus": carcharodontosaurus (which coincidentally likely coexisted with the titular theropod); it was much less pneumatic and more heavily-constructed (whereas allosaur skulls were the direct opposite). As for its width, it was very similar to the false gharial, and was a good deal broader than the snout of the Indian gharial. Here you can see it both in dorsoventral and lateral views, the latter of which represents a deeper profile than all modern slender-snouted crocodilians both generally and proportionally (thus making its overall proportions more even). Its width is roughly similar to the snout of the false gharial:



Furthermore, its dentition (teeth) was unique for theropods as well. While carcharodontosaurus (an animal that was designed for hunting large terrestrial herbivores) possessed thin, serrated, knife-like teeth that were designed for slashing, spinosaurus had what could be considered the direct opposite. Its largest teeth (located in the frontal parts of its snout) were rather slender, sharp, and circular in cross-section while completely lacking serrations for cutting. They were not at all structured for slashing but instead piercing and gripping:

(Note this one is considerably wider, but yet still rather elongated, and a good deal away from being considered excessively laterally-broadened like the more common theropod dentition)





But the overarching question remains, what was its diet? Well fish, for the most part. But like the majority of slender-snouted crocodilians, it most definitely could kill smaller terrestrial animals given its size. What it was adapted to do was plunge its slim but yet robust jaws into the water and clamp down with "decent" strength, where its sharp and conical teeth would pierce the skin efficiently.

[Godzillasaurus]

New studies have recently been published which indicate that, as long as the hind leg-body size ratio is not thrown-off by an age difference (such as a much smaller and more immature juvenile having possessed those legs while a fully-grown adult's body-based remains were fossilized), spinosaurus would have probably been much more crocodile-like ecologically than it has previously been thought of as a bipedal land-based predator as in most other theropods.

If these hold true, then it is simply probable that spinosaurus would have moved fluently in water much like a duck or a surfaced crocodile. And as for terrestrial movement, it would have likely employed quadrupedalism (which is a downright first for such a large theropod, and so far probably for all theropods in general!) through knuckle-walking perhaps. Even though its robust forelimbs would have been capable of resisting its frontal body weight, this quadrupedal behavior would have made terrestrial hunting much less likely, especially if it was hunting other dinosaurs like carcharodontosaurus (which would have been more at home on land than spinosaurus was).

Spinosaurus was still very likely the longest and heaviest theropod found thus-far, but its ability to overpower large herbivores on land is way lessened, and it would have probably relied on fish and other smaller aquatic animals even more as part of its diet. Its physical characteristics, aside from its enlarged spine, elongated neck, and a few others, would make it a lot like a dinosaurian crocodile in life; even its skull and teeth were very closely reminiscent of those of piscivorous crocodilians!

[batcheno]

That's my favorite dinosaur