|
|
Post by Godzillasaurus on Nov 22, 2013 6:41:50 GMT 5
I never said that it was rugose all over.
Are you talking dorsally, or laterally? Large, old male crocodiles can get insanely thick skulls, whether it be dorsally or laterally. Compared to younger crocs, however, kaprosuchus has an overall wider and deeper snout. It is unlikely that this kaprosuchus reached its full size potential, and may have even been a female.
Of course the largest crocodylus thorbjarnarsoni specimens would have a more robust skull than a smaller crocodylomorph, as they grew to 25+ feet in length.
|
|
blaze
Paleo-artist 
Posts: 766
|
Post by blaze on Nov 22, 2013 7:48:03 GMT 5
You said Very rugose skull, what do you mean by that then? About it being thick and robust, I mean overall, as I said, the rostral proportion of its snout is comparable to the mean of nile crocodiles and is not particularly deep in lateral view either, I was expecting a critique on my size chart because I used that croc haha but what about this one.  Not really much of a difference, and that skull either belongs to a large female or an average male, not even 3m in length. |
|
|
|
Post by Godzillasaurus on Nov 22, 2013 7:58:32 GMT 5
As in strongly-built and rough in texture. Most primarily aquatic animals tend to have streamlined and smooth skulls (at least compared to an animal like kaprosuchus). We do not see that in kaprosuchus, especially at the front of the upper jaw.
Well, it is still HIGHLY unlikely that the animal found was its full size potential, let alone a for-sure adult specimen. And the new picture won't show up...
|
|
blaze
Paleo-artist
Posts: 766
|
Post by blaze on Nov 22, 2013 8:03:45 GMT 5
All croc skulls are rough in texture...
I'm not saying this specimen was the biggest ever, I just think that anything bigger than "american alligator sized" is probably an exaggeration, even if this specimen was not fully grown, 3m something male american alligators haven't reached asymptotic size either.
mmm it's showing for me.
|
|
|
|
Post by Godzillasaurus on Nov 22, 2013 8:38:05 GMT 5
For most generalist crocodilians, yes, but in kaprosuchus we see a specialized type of "rugoseness" in the frontal area of the upper jaw. It is again theorized that this was an adaptation for hunting techniques (and to provide defense in conflicts).
|
|
|
|
Post by Infinity Blade on May 18, 2014 7:56:01 GMT 5
Many (if not most or perhaps even all, as I can't think of any that don't atm) predatory fully terrestrial crurotarsans had relatively narrower snouts than the semi-aquatic crocodilians we're familiar with and their whole skull morphologies just aren't quite alike at all. And just look at Kaprosuchus' skull. I think that should at least give us a bit of a hint as well.
|
|
|
|
Post by theropod on May 18, 2014 14:31:17 GMT 5
Kaprosuchus skull certainly has a few peculiarities, but its still comparable to extant amphibious species. It differs in a few details, but its overall built is similar.
Compare that to the oreinirostral skulls of fully terrestrial species of crurotarsan (prestosuchids, rauisuchids, poposaurs, sebecosuchids, stem-loricata…) and you get that this skull is not indicative of fully terrestrial lifestyle. It may have been a bit more terrestrial than typical for extant crocodilians, but not to an extreme degree. Its cranial robusticity is comparable to robust-snouted crocodiles of similar size, and its size is similar to an American Alligator.
It was about this specimen’s size–surely not the biggest ever, but also surely not a 6m monstrosity.
And btw the skulls of many extant crocodiles are also "very rugose" and "not-so-streamlined", not less so than that of Kaprosuchus. We aren’t comparing it to Thalattosuchians here. What’s special about Kaprosuchus is that it has those very long caniniform teeth, but those can be explained for an aquatic animal just as well as for a terrestrial one. In fact, Mastodonsaurus also has hypertrophied caninifor teeth, and nobody is seriously gonna assert it was fully terrestrial.
|
|
|
|
Post by Godzillasaurus on May 22, 2014 3:07:57 GMT 5
I do not deny that kaprosuchus was probably an at least partially aquatic animal. But yet, you must realize that this animal's feeding apparata does not seem to correspond well with modern semi-aquatic forms. Instead of possessing relatively similar-lengthed dentition that is all the same general shape (aside from being longer and sharper in the frontal snout regions, and shorter and blunter in the rearmost regions; as with robust-snouted species today, but not so-much more gracile ones), kaprosuchus seemed to have been much less adapted for the same kind of killing. Although we really only have one skull to work with, it has been stated that they were laterally-compressed and likely serrated. Also note that the enlarged caniniforme dentition (probably its most famous asset) appear to have been designed for killing most of all, as they were particularly well-structure for puncturing, and probably fatally as well (maybe similar to smilodon):  And this creature most likely possessed a very strong bite force as well. All of this seems to indicate that it may have killed animals with fatal (and probably very powerful) biting through the combination of its rather sharp and spike-like but yet rather laterally-compressed dentition (appear to have been similar to tyrannosaurus in this regard, at least until we get a better image of them dorsally and ventrally) and likely very powerful jaws to create massive puncture wounds into small-medium sized dinosaurs (like modern crocodilians, it was likely not well designed for attacking animals much larger). MY THEORY (because this animal is so little-known, even scientifically) is that it would have killed terrestrial animals as such and did not kill terrestrial creatures by ambushing them from the water. But again, just my theory (I have made plenty of those), just like how I propose that spinosaurus was a more powerful animal than carcharodontosaurus, and how diplodocid tails can be used to cripple smaller predators |
|
|
|
Post by theropod on May 24, 2014 16:28:19 GMT 5
It corresponds much more closely to that of modern semi-aquatic forms than to that of extinct terrestrial forms.
What you are describing there is what is seen in Kaprosuchus. Kaprosuchus simply displays an extreme hypermorphosis of these features (heterogeneity in terms of tooth sizes). In no way does that necessarily make it any more or less aquatic.
The authors explicitely describe the carinae as smooth (i.e. non-serrated). Crocodile teeth aren’t always perfectly round in cross-section, and yes, this one has carinae (as some other specimens described by Sereno et al. btw). Still, I don’t see what that proves.
Crocodiles today have teeth of varying lenghts, variabilities and shapes, depending on what they feed on. Macrophagous crocodylus species for example have enlarged anterior maxillary teeth, while piscivores like gharials have uniform tooth sizes, and those of caimans and alligators are shorter and blunter. But yet all extant crocodiles are semi-aquatic.
|
|
|
|
Post by theropod on May 24, 2014 16:37:34 GMT 5
There’s no reason it could not have killed very large animals. It is actually possible that was exactly what its large, carninated teeth were made for. There just isn’t any reason why this must mean that it was terrestrial, or that its skull was proportionally smaller. For all we know, it would have had better chances if it hunted large animals from the water, just like extant crocodilians.
The teeth of T. rex are rather blunt actually. But I think they are a decent analogy, just judging from the pictures of course. Anyway I don’t see why its bite force should be higher than that of extant crocodylians with comparable rostral robusticity.
That is at best a hypothesis, but one that has not been verified. The observations that can be made from its cranium make perfect sense for an aquatic animal.
|
|
|
|
Post by Godzillasaurus on May 25, 2014 5:28:29 GMT 5
I do agree that its snout is in fact reminiscent of modern species, as it is quite broadened but yet not very deep, but yet it seems probable that this so-called "shield-like structure" on the tip of its snout could have been used as a weapon for hunting terrestrial animals. This was theorized by paleontologists. But as for its teeth- they were very much varied from those of the typical species we see today.
I realize that, but they appear to have been far too small and rudimentary to have been used for any sort of predation. Not to mention their obvious insignificance compared to the much larger and more lethal caniniforme teeth farther up front in the snout. Modern broad-snouted crocodiles typically possess two different "forms" of dentition that are only slightly differentiated (specialized): longer and sharper teeth at the front ideal for gripping and piercing, and shorter blunter ones near the back best suited for crushing hard-shelled animals like shellfish and turtles in larger species (while they were designed to do this, there is little indication that they were actually evolved to do this, as they could simply just be, again, rudimentary in nature. Having longer teeth near the rear would be pointless, as the mouth could not fully open with a gap between both jaws at that region).
It simple seems unlikely that kaprosuchus would have taken hard-shelled animals as a good portion of its diet (unlike something like deinosuchus for example). Its caniniforme dentition (which were also laterally compressed, according to online sources, but yet of course I have never analyzed them fully myself) seemed far to significant.
Where? I might just be late, that's all.
Carinae is a large indication of diet. Modern crocodilians possess conical but yet pointed dentition because they are designed to grip (and fish make up a large part of their diet, is EVERY species. Of course they aren't perfectly circular in cross section, but does that really mean anything? They are never described as being narrow and designed for cutting at all). Modern crocodilians do not possess narrow and serrated dentition because they are technically not adapted to hunt large terrestrial animals, much unlike many species of predatory theropods. It is like comparing spinosaurus and carcharodontosaurus again in this regard: one is perfectly adapted for puncturing the hides of fish while the other would have hunted large animals such as titanosaurs. It is really the same with crocodilians, especially when you consider the similarities and differences of the Indian gharial and the American alligator (both have conical pointed teeth, but yet it is quite obvious which one is only really adapted for hunting fish)
There is variation, but it is rather insignificant. It is NOTHING like what we see in kaprosuchus, whose only really practical dentition in feeding were its enlarged tusk-like ones. Like I said, crocodilian teeth are typically sharper and longer towards the front region of their snouts, but shorter in the rear. But yet there is not all THAT much difference, at least nothing like we see in kaprosuchus' maw.
I see what you are saying, except for the last sentence. Modern crocodilians can kill terrestrial animals because they 1. are adapted for ambush in this regard (they look just like logs to any mammal taking a drink such as wildebeest which are notable for mistaking them), and 2. are obviously not designed for true killing and instead rely either on size or their advantage of a primarily aquatic lifestyle to kill. A creature with dentition clearly best designed for killing was not particularly structurally sound for this. It was most likely still at least partially semi-aquatic though, just maybe not as much as modern crocodilian genera and their closest kin.
I meant that they would have likely worked similarly to tyrannosaurus through the use of sheer force and puncturing ability to kill. Of course they are not perfectly analogous, but they seem more similar physiologically to tyrannosaurids than to modern crocodilians. Note that tyrannosaurus teeth are still at least somewhat sharp, just not especially. Kaprosuchus seemed to have had sharper-pointed and more slender dentition at best, but yet still probably similar.
Also, I do not deny that its bite force and snout strength was similar to that of modern broad-snouted crocodilian species.
|
|
|
|
Post by spinodontosaurus on May 26, 2014 1:03:57 GMT 5
Kaprosuchus could well have been doing something different to modern crocodilians, but what you are doing is searching for every difference between them, and then searching for ways you can spin it to support the terrestrial hunter standpoint.
Nothing you have put forward is even remotely convincing in my opinion, nor was what was put forward in Sereno & Larsson (2009). For all intents and purposes, Kaprosuchus has a skull no different from extant crocodilians, the only difference is that it has some pretty whacky teeth. But to suggest that this means it is a terrestrial hunter? Come on, there's stretching the realms of possibility, and there's this.
|
|
|
|
Post by theropod on May 26, 2014 2:23:05 GMT 5
Godzillasaurus: Could you elaborate on how this supposed "shield-like" structure is so probable to have been a weapon for hunting terrestrial animals? Why not aquatic animals? There are actually aquatic animals that use their snout for ramming, while there are no terrestrial animals that do so. And why doesn every little rugosity have to be a weapon at all? There are all sorts of things that this could have been, but nothing of it seems to justify a hypothesis that it was related to terrestrial lifestyle.There are also many imaginable reasons why an animal may have strongly keratinized skin on a part of its snout. I presume you misunderstood me, otherwise, you’d be calling Kaprosuchus’ gigantic teeth, for which it was named, small and rudimentary.These teeth are enlarged, like in an extant crocodile with exagerated features. The teeth in the back of crocodile mouths aren’t rudimentary, neither are they necessarily designed for durophagy. As you explained yourself, there would simply be no point in having larger teeth in this region. that doesn’t mean they don”t play their role in biting and prey handling. There’s no reason why it shouldn’t have done so. I don’t know how common these animals were in its habitat, but its teeth appear well-suited to puncture tough shells. YOu compared them to T. rex’ teeth earlier, T. rex was also durophagous at least on occasion. Of course one would expect a different morphology if it was specialized for this sort of thing, but the same goes for extant crocodiles. Page 74 in Sereno & Larsson 2009 Yes of course. But for that it is necessary to interpret them correctly. It does, because "labiolingually compressed teeth" doesn”t equate to "narrow, sharp cutting teeth". The teeth of Kaprosuchus are still very robust, just like crocodile, T. rex or pliosaur teeth, despite being labiolingually flattened. Exactly, and neither are those of Kaprosuchus! Yes, but Kaprosuchus is not a theropod, it does not have serrated dentition, and ziphodont (and serrated) teeth are found in aquatic predators as well. Kaprosuchus’ teeth have carinae, but their cutting efficiency is not studied, it is fully conceivable they are comparable to tyrannosaur teeth, i.e. rather blunt puncturing and crushing tools. Btw Laganosuchus’ teeth are also described as flattened and with cutting edges, even specified to have been sharp! Does that automatically make it a terrestrial macropredator? that’s like saying the only functional feeding dentition of a mammoth were its tusks! I already diskussed that point. Kaprosuchus exagerates typical features of macrophagous crocodylians. It is logical to assume it hunted large prey. That doesn’t make it logical to assume it was terrestrial, because extant crocodylians that hunt large prey are not terrestrial either and Kaprosuchus lacks features that would be functional evidence of a terrestrial lifestyle. And those things could also have improved Kaprosuchus’ sucess rate, because for all we know it could also have launched an aquatic ambush on drinking animals. I don’t understand this sentence. All those maybes and likelys… But why, that’s the question? Which would work perfectly well for a semi-aquatic animal for all we know.It will likely be advantageous if, compared to Crocodylus, it was more specialized in taking big prey. Doesn’t imply a fundamentally different lifestyle, just somewhat different prey-preferences (mostly regarding average prey size). You mean morphologically. yes, and the rest of its skull is quite consistent with a modern crocodile, implying a similar habitat, locomotion and physiology. If it was that different in those points, its skull morphology would also remind you of T. rex, as do those of many terrestrial crurotarsans (e.g. Postosuchus, Prestosuchus…)
|
|
|
|
Post by Godzillasaurus on May 28, 2014 4:18:37 GMT 5
Oh yea, forgot about this. Don't dolphins regularly use their snouts as weapons against sharks for defense? Hmm... That is a logical hypothesis.
Depending on the length of the teeth in the rear regions of the snout, their function would vary. Of course I wasn't referring to the enlarged caniniforme teeth (which were of course its most prominent unusual feature and its namesake). The usefulness of teeth in correlation with their position in an animal's snout tends to rely on its prey type; for example, a creature designed for crushing hard-shelled animals will typically possess a widened snout overall and less emphasis on longer teeth in the very front than something that hunts fish (these animals typically tend to possess much sharper teeth present in the tip of their snout. A relevant example would be the Indian gharial, which has the longest teeth present in the front of its maw). Broad-snouted crocodilians typically possess molariforme teeth in the back that can be used for crushing in correlation with their bite forces and snout shapes.
But for kaprosuchus, it seems quite unlikely that they would be used as such, as they were not only shorter proportionally than those of many species of more aquatic crocodylomorphs (to the point of being practically useless most likely), and they paled compared to the creature's much longer and more lethal caniniforme teeth farther up front. Their presence does not mean much in terms of feeding, as they could simply be evolutionary. A simple example would be wisdom teeth in humans; they are not necessary and are really only "just there" (they are simply from our ancestors, which had longer snouts to compensate for their presence). And they are quite deadly, as they can cause deadly infections in the mouth if impaction occurs. In fact, some people don't even have wisdom teeth because they are slowly becoming completely recessive. The same thing can be said about kaprosuchus.
Well it could have certainly done so, assuming that its bite force was powerful enough and its jaws were strong enough (which they were), but the enlarged stabbers would not be doing the feeding here, as those were most probably for killing larger vertebrates. Recall that broad-snouted crocodilians normally crush such animals with the blunter molariforme teeth in the rear, which are actually designed for such. Simply, despite the killing capacity of the caniniforme dentition itself, they were not for crushing hard-shelled creatures.
Tyrannosaurid dentition is more-so like a thick oval in cross-section, which does in fact equate to such. But crocodile dentition is pretty much conical, albiet VERY SLIGHTLY more narrow than a circle in cross-section. Of course we really don't have much of kaprosuchus to work with (only a few descriptions and images thus far), so there really is not much else to say in this regard.
Assuming that they were narrower and sharper-edged than those of modern semi-aquatic species, then the cutting efficiency would definitely be much higher. But yet, is there any real indication that the enlarged morphology of the caniniforme dentition alone would not be enough to "prove" a different lifestyle from modern semi-aquatic species? If anything, the elongate and large morphology as well as the simple positioning in such a broadened snout (both posteriorly and frontally) seems to indicate anything from such a large reliance on fish (or any killing style where gripping is largely involved). Of course the most common tooth design of mainly piscivorous animals is of course long and rather slenderized pointed teeth, but in species where fish make up the vast majority of the creature's diet, the snout they are rooted in is typically specialized as well (eg: slender-snouted crocodile species, Indian gharial, many pterosaurs, spinosaurus, etc).
The mammoth's tusks were for defense, courtship, and possibly foraging, but most certainly for not feeding (I am sure you know this). But it was still a mammal whose cheek teeth were specialized for grinding vegetation. So this is an irrelevant analogy. Kaprosuchus was a homodont whose rearmost dentition was most likely evolutionary and useless for the most part.
In any case, how would the tusk-like dentition be any indication of primarily aquatic life either? They were not truly ideal for the same hunting as modern crocodilians do today
Just a theory. I saw it on a documentary. It is definitely possible given the lack of an impressively deepened and pneumatic skull
Since when was such dentition ideal for gripping? The teeth of modern forms is DESIGNED for such, and further requires them to kill through a different means than simple biting.
Morphologically and physiologically
|
|
