Sarcosuchus imperator vs Carcharodontosaurus saharicus

[theropod]

The El Rhaz Formation is late Aptian to early Albian, and Carcharodontosaurus saharicus is Albian to Cenomanian.

[creature386]

Jan 12, 2014 18:28:09 GMT 5 Infinity Blade said:

^You made a separate thread with T.rex vs. Sauroposeidon to keep a thread clean. I'm planning on the same.

Yes, but many people didn't get why this thread was necessary. Given there is a huge size disparity, I doubt there will be much of a discussion.

[creature386]

Jan 12, 2014 20:45:25 GMT 5 theropod said:

The El Rhaz Formation is late Aptian to early Albian, and Carcharodontosaurus saharicus is Albian to Cenomanian.

Even then, we don't know if Carcharodontosaurus already existed in the early Albian.

[theropod]

Well, according to the Palaeobiology database there are even fossils referred from the Cenomanian.

[Godzillasaurus]

I think the term "hatchet bite" is somewhat misplaced here. Carcharodontosauridae donÂ’t display the same marked adaptions towards this as allosauridae. They rely, so similar extends, on pulling, head-depression and the sheer size of their jaws and lenght of their toothrows for killing.

What sort of adaptations are you referring to? Both families possess similar morphologies that indicate similar killing styles: deep snouts, serrated dentition (designed for cutting and ripping for the most part), powerful necks, and lack of exceptional bite forces. Allosaurids, too, seem reliant on backwards pulling as well (as the direct result of a hatchet-bite or in the case of a flank bite), as their tooth morphologies are overall similar.

You again ignore that Sarcosuchus teeth are not cimparable to those of relatives with a comparatively high reliance of crushing and tissue damage of large animals

Modern opportunist crocodilians do not kill with tissue damage

your sole argument is that they are thick. So what?

They are thick and correspond perfectly with the animal's bite force and snout width. Compared to more specialized animals, they simply do not compare in that sarcosuchus' teeth are much less adapted for piercing deeply but rather piercing into the hides of animals in conjunction with powerful biting forces. Teeth with such strong reliance on bite force are disadvantageous (in that they are not as well adapted for piscivory, which normally requires teeth that are more slender in shape and are able to grip slippery aquatic animals as opposed to retain a stable grip on very large terrestrial animals and be very resistant vertically) and overall unnecessary for such specialized animals like modern slender-snouted crocodilians.

Higher reliance and correlation with bite force in this case actually points in the opposite direction from specialization in piscivory.

hey are thick, but numerus, relatively uniform, and small.

And those of spinosaurus are very much the direct opposite: slender and designed for piercing deeply as opposed to doing so in conjunction with powerful biting (they were still very strong, just far more specialized), less numerous, definitely not uniform (possesses longer dentition at the tip of its snout and in the maxilla), and definitely not small. And we know that spinosaurus had a very indicative morphology for piscivory. That is why I believe tooth size to be a horrible indicator for diet.

Your point, the robusticity of the teeth, can easily be explained by the sheer size of this creature. Additionally, adult Mecistops or Tomistoma also get more robust teeth than the immature ones you all the time compare it to.

Again, the teeth were very robust, but they also indicate heavy relation with bite force as opposed to specialization in piscivory:



The premaxillary teeth seem most relevant and easy to talk about, as they, despite being arranged similarly to primarily piscivorous animals, possess a far different morphology. They are broad, very resistant (both laterally and dorsoventrally), correspond heavily with bite force and bulla robusticity (so what if it had a damn hole!? That does not make it a weak structure!), and they form a perfect "hook" as opposed to interlocking with the dentary teeth and pointing outward to a certain degree. They, in conjunction with the bulla, seem to form a perfect macrophagous structure/tool.

Even though the posterior and dentary teeth retain the same basic morphology (being very thick and designed for similar crushing/piercing and gripping purposes), they seem particularly harder to discuss due to so many controversies regarding their number. They still, however, do not imply piscivory despite their uniform nature and large quantity for reasons that I have explained. It was a homodont; all of its teeth retained generally the same shape and anatomy: pointed and thick designed for piercing in conjunction with bite forces acting against them.

And I state again that gripping has the positive side effect of puncturing, and that <i>Spinosaurus</i>Â’ teeth excelled at gripping simply by being good at puncturing but bad at tearing.

The gripping function of spinosaurus' teeth is just the reason to believe that its snout would need to overall stronger. They excelled as piercing and gripping large fish, so naturally the stresses experienced would be much higher than an animal that killed more quickly and did not kill and hunt by gripping. They, again, correlate perfectly with snout shape in that they indicate high reliance on large fish as part of their diet.

But this should show you that merely being designed for gripping purposes does not imply massive resistance of the snout. Gharials obviously donÂ’t have it, but are still adapted for gripping. This works because what they are gripping doesnÂ’t excert very strong forces.

Oh, but it does. With sarcosuchus, there is really an obviously high aptitude for crushing and gripping large animals. Unlike the Indian gharial, which was restricted to small trout-sized fish as most.

There is no reason to believe that both sarcosuchus and spinosaurus would not experience any sort of large-degree stress in predation, as the animals that they hunted were fundamentally larger. This goes back to my last point; the fish that were caught and eaten by spinosaurus were very large, and the correlation between snout morphology/strength and tooth morphology/strength indicates that it was well adapted for resistance in gripping these huge fish.

[blaze]

The paleobiology database cites Sereno et al. (1996) and Lapparent (1951) as the source of Cenomanian Sarocusuchus remains, Sereno et al. (1996) mentions that in the Kem Kem Beds there are remain of a large crocodilian, mentioned as cf. Sarcosuchus and they don't say anything more.

I don't have Lapparent (1951) but we'll be dealing with 60 year old stratigraphy and taxonomy.

Maybe there is a Sarcosuchus species or very related taxon living with Carcharodontosaurus but is it likely to be Sarcosuchus imperator itself?

[theropod]

We cannot say with 100% certainty. But I think they are close enough to be considered sympatric, considering both Carcharodontosaurus saharicus dates back to the albian and Sarcosuchus may date back to even younger than that.

[blaze]

So... Sarcosuchus imperator lived for over 10 million years without changes (or more like 30 million years, considering supposed Hauterivian-Barremian remains)

btw what are the Albian Carcharodontosaurus remains?

I think we should consider sympatric taxa only those that have been unequivocally found if not in the same quarry at least the same level of a Formation but well that's just my opinion.

[theropod]

The syntypes, a number of teeth and vertebrae.
archosaur.us/theropoddatabase/Carnosauria.htm#Carcharodontosaurussaharicus

[blaze]

The Continental Intercalaire spans a huge amount of time, I'll like to see more current data on the matter,

I only have a translated copy of Lapparent 1960 and this is what it says about the fauna described in the paper

In conclusion of this analysis, we accept that the dinosaur fauna which I will describe belongs essentially to the Lower Cretaceous; it reaches into the Albian and perhaps up to the lower Cenomanian. This is well confirmed by the existence of this same fauna in extreme southern Tunisia, at diverse levels in the Dahar cliff, surrounded by the marine Upper Jurassic below and the marine upper Cenomanian above [Lapparent, 1953a; Basse, 1953]. The dinosaurs of Baharija in the Egyptian desert and those of Kem Kem in southern Morocco are contemporaneous with more elevated levels, their localities being situated immediately below the marine Cenomanian or being intercalated with the oyster beds.

Lapparent (1960) describes more material than I thought existed for Carcharodontosaurus and I don't remember it being mentioned in more recent papers, you have to remember that this is 50 year old taxonomy and stratigraphy, for example, Lapparent concludes that Carcharodontosaurus evolved from cretaceous megalosaurids and belonged in the Tyrannosauridae and was intermediate in size between Jurassic theropods and such late cretaceous giants as Gorgosaurus.

Those remains might as well be something else, maybe Eocarcharia? maybe not even Carcharodontosaurids at all?

Edit:

Carrano et al. (2012) mentions the findings of Carcharodontosaurus teeth but it doesn't seem that any of the fossils described in Lapparent (1960) appear in the hypodigm.

Largely because of the distinctive crenulations present on the teeth of Carcharodontosaurus, the genus has been identi?ed across mid-Cretaceous deposits of North Africa, primarily from the ‘Continental Intercalaire’ and its descendant units; these beds vary in age from Albian through Cenomanian. The characteristic crenulations of isolated ‘Carcharodontosaurus sp.’teeth are present in other derived carcharodontosaurids such as Giganotosaurus (MUCPv- Ch 1) and Mapusaurus (Coria & Currie 2006), vary in prominence between individuals and along the tooth row, and are observed in a lesser developed form in numerous other tetanuran taxa (Brusatte et al. 2007). Given the recent identi?cation of a second species from Niger (Brusatte & Sereno 2007), we consider it prudent to refer such isolated teeth to cf. Carcharodontosauridae indet.

Carrano et al. (2012) also gives the age of the genus as Albian?-Cenomanian, indicating that the Albian age is not certain.

[spinodontosaurus]

Because there are nowhere near as many parallels as you claim to the premaxillae of more specialized animals. That is the bottom line

The point being is that you CAN draw very good parallels between the two, and logical explanations for the structure have already been presented (e.g. heat loss). Instead you reject all this, with no good reason, and proudly proclaim it is an effective predation tool which all revolves around the concept of it being wide.

They are thick and correspond perfectly with the animal's bite force and snout width.

EXACTLY. The snout width and morphology is consistent with modern day slender-snouted crocodilians, bite force is rather besides the point (because it is more tied to body mass than tooth morphology, and is independent of diet), whilst the tooth morphology is also consistent with modern day slender-snouted crocodilians. Therefore, the logical conclusion is that Sarcosuchus' predatory habits and capabilities were probably close to that of modern day slender-snouted crocodilians.
Why is this so far-fetched and un-reasonable? It is not as if the habitat where Sarcosuchus lived was devoid of prey that would fall into this category (which does not solely include fish, although I would wager they made up a significant proportion of it's diet), in fact it was teeming with the stuff.

[Godzillasaurus]

The point being is that you CAN draw very good parallels between the two, and logical explanations for the structure have already been presented (e.g. heat loss). Instead you reject all this, with no good reason, and proudly proclaim it is an effective predation tool which all revolves around the concept of it being wide.

If you read any of my past posts, I never used its width solely, but rather the general morphology of that area in conjunction with its dental morphology rather indicates high correlation with bite force.

EXACTLY. The snout width and morphology is consistent with modern day slender-snouted crocodilians, bite force is rather besides the point (because it is more tied to body mass than tooth morphology

Actually its tooth morphology seems to correspond heavily with bite force. They were well adapted for resistance against crushing; not something that we would see in a more specialized animal.

whilst the tooth morphology is also consistent with modern day slender-snouted crocodilians.

Now I have no idea why you believe this aside from size (which really wasn't THAT small) and arrangement.

[blaze]

Teeth similar in length and width to those of extant ~1 tonne crocodilians, in a crocodilian that weighted at least 5 tonnes are definetely not what we would expect if said animal was specifically adapted to produce higher bite forces than those suggested by its size alone. We don't see small numerous teeth in shallow jaws in extant durophagous crocodilians like the broad-snouted caiman and the Chinese alligator nor in any other animal specifically adapted to crush bones like Tyrannosaurus rex, Hyenas, borophagine canids, Anteosaurus, what they do show exactly the opposite of the condition seen in Sarcosuchus.

edit: removed sarcasm.

[Godzillasaurus]

Quote: Teeth similar in length and width to those of extant ~1 tonne crocodilians, in a crocodilian that weighted at least 5 tonnes are definetely not what we would expect if said animal was specifically adapted to produce higher bite forces than those suggested by its size alone.

Bite force is not determined by tooth size or shape...

Quote: We don't see small numerous teeth in shallow jaws in extant durophagous crocodilians like the broad-snouted caiman and the Chinese alligator

Sure we do:

www.boneroom.com/welcome.aspx?c=790&i=3240&n=ChineseAlligatorSkullCast#1

Quote: nor in any other animal specifically adapted to crush bones like Tyrannosaurus rex, Hyenas, borophagine canids, Anteosaurus, what they do show exactly the opposite of the condition seen in Sarcosuchus.

Retread my last posts. Sarcosuchus does not have to be very well designed for crushing bone to necessarily be well adapted for such high degree exertion of force. Just as with modern crocodiles, its teeth were very well designed for piercing and yet they still retain a very robust morphology not seen in particularly more specialized and gracile animals. There are many features present in slender-snouted crocodilians that are seen in similar specialized animals but yet are not found in sarcosuchus in vice-versa.

The ability for sarcosuchus to exert such large force and resist it simultaneously in addition to resistance in gripping does not indicate such large reliance on fish. Such strong bite forces and robust dentition very well designed to withstand it (they correspond perfectly) are unnecessary for a primarily piscivoruous lifestyle and instead seem to indicate a high aptitude for gripping large animals as we see in extant broad-snouted crocodilians. Fish likely made up a large part of its diet, but it was much less specialized than you claim it be.

[blaze]

It's correlated to the mass of the croc I know but if the teeth are about the same size as those of a 6m saltie then they are no stronger themselves than those of a 6m saltie, which means that every time Sarcosuchus bites with full force it's subjecting its teeth to proportionally much higher stress than if they were not small compared to its body size, this is not in any way an adaptation to resists proportionally huge forces.

The link doesn't work, the website seems to be down.

Here a 20cm long skull of a Chinese alligator



Well let's see, 12 or 13 teeth in the maxilla, all of them fairly broad and not really small compared to the rest of the skull, I don't see the small and numerous teeth you mentioned.

All crocodilianss are technically bone crushers, even gharials (!) but crocodilians specifically adapted to bite hard stuff in a daily basis (be it bones, turtle shells or mollusk shells) show the exact same adaptations as the rest of bone crushers, short robust jaws with few big and broad teeth, Sarcosuchus doesn't have any of this features which means that is no more specialized for those things you claim than any random crocodilian, probably even less so than average for all the reasons that I and others have previously outlined.

If Sarcosuchus was as well adapted to prey on big animals as the saltwater and the nile crocodile then I suppose Deinosuchus was a monster, it's snout was at least twice as wide and twice as tall and its teeth were twice as big in all dimensions as those of Sarcosuchus! what horrible things were such robust and powerfully built jaws capable of doing.

btw, the skull of Deinosuchus is actually proportioned like those of American alligators and fully grown saltwater and nile crocodiles.