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Carcharodontosaurus saharicus v Tyrannosaurus rex
Topic Started: Jun 8 2012, 05:34 PM (129,971 Views)
Taipan
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Carcharodontosaurus saharicus
This huge meat eater was 45 feet long (5 feet longer than T-rex) and weighed 8 tons, making it one of the largest carnivores that ever walked the earth. This African carnosaur had a gigantic 5’4" long skull and enormous jaws with 8" long serrated teeth. It walked on two legs, had a massive tail, bulky body and short arms ending in three-fingered hands with sharp claws. Carcharodontosaurus is one of the longest and heaviest known carnivorous dinosaurs, with various scientists proposing length estimates ranging between 12 and 13 m (39-43.5 ft) and weight estimates between 6 and 15 metric tons. Its long, muscular legs, and fossilized trackways indicate that it could run about 20 miles per hour, though there is some controversy as to whether it actually did, a forward fall would have been deadly to Carcharodontosaurus, due to the inability of its small arms to brace the animal when it landed. Carcharodontosaurus was a carnivore, with enormous jaws and long, serrated teeth up to eight inches long.

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Tyrannosaurus rex
Tyrannosaurus is a genus of coelurosaurian theropod dinosaur. The species Tyrannosaurus rex (rex meaning "king" in Latin), commonly abbreviated to T. rex, is a fixture in popular culture. It lived throughout what is now western North America, with a much wider range than other tyrannosaurids. Fossils are found in a variety of rock formations dating to the Maastrichtian age of the upper Cretaceous Period, 67 to 65.5 million years ago.[1] It was among the last non-avian dinosaurs to exist before the Cretaceous–Paleogene extinction event. Like other tyrannosaurids, Tyrannosaurus was a bipedal carnivore with a massive skull balanced by a long, heavy tail. Relative to the large and powerful hindlimbs, Tyrannosaurus forelimbs were small, though unusually powerful for their size, and bore two clawed digits. Although other theropods rivaled or exceeded Tyrannosaurus rex in size, it was the largest known tyrannosaurid and one of the largest known land predators. By far the largest carnivore in its environment, Tyrannosaurus rex may have been an apex predator, preying upon hadrosaurs and ceratopsians, although some experts have suggested it was primarily a scavenger. The debate over Tyrannosaurus as apex predator or scavenger is among the longest running in paleontology. Tyrannosaurus rex was one of the largest land carnivores of all time; the largest complete specimen, FMNH PR2081 ("Sue"), measured 12.8 metres (42 ft) long, and was 4.0 metres (13.1 ft) tall at the hips. Mass estimates have varied widely over the years, from more than 7.2 metric tons (7.9 short tons), to less than 4.5 metric tons (5.0 short tons), with most modern estimates ranging between 5.4 and 6.8 metric tons (6.0 and 7.5 short tons). Packard et al. (2009) tested dinosaur mass estimation procedures on elephants and concluded that dinosaur estimations are flawed and produce over-estimations; thus, the weight of Tyrannosaurus could be much less than usually estimated. Other estimations have concluded that the largest known Tyrannosaurus specimens had a weight exceeding 9 tonnes.

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Blue orca
 
Tyrannosaurs Rex vs Carcharodontosaurus
Edited by Taipan, Apr 24 2015, 10:18 PM.
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blaze
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@The Reptile
You are making the assumption that it implies how advanced they are and then using it to justify your idea that because they are given those names they have to be less advanced than mammalian teeth, this is circular logic, we could find a reptile with a dentition that is an exact clone of mammalian dentition and their teeth would still be called "molariform" and "caniniform", the authors of the study explain how complex the dentition of Pakasuchus is and say several times that it matches that seen in mammals.

No non-mammal has carnassials? true because that's how the word is defined on top of other aspects regarding their evolution, therefore you can't call carnassial anything outside of the mammalian linage.

No non-mammal has dentition as complex and advanced as that of mammals? categorically false.
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theropod
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Quote:
 
Allosaurus wasn't particularly large either
Twice the size of Ceratosaurus. That makes it more likely to prey on prey of a given large size than Ceratosaurus.

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yet it would still most likely have much less trouble bringing down a large sauropod than a spinosaurid or crocodilian much larger than it.
Depends on how much larger, and this is unrelated to the point you were arguing. Obviously certain functional morphologies are better for killing sauropods than others–that’s what I was saying from the beginning, hence also why you can infer similar diets from similar teeth.

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Actual specialization does not have a huge reliance on the size of the predator (think; are wolves inefficient hunters of bison just because they are rather small in size?)
No, but inefficient hunters of elephants. Of course size is part of specialization. Prey/Predator size ratios tend to be in a certain range. If the prey is big, the predator preying on it has to be big as well. Not as big as the prey animal, but size helps.

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Flat-topped, like the molars of mammalian herbivores
Those are extremely variable in morphology, depending on what the herbivore feeds on, actually. Flat-topped isn’t a good way to describe them.

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But having similar-shaped dentition is one thing; tooth size and the physiology/morphology of the skull/jaws is also a factor to consider.
Tooth size also concerns the teeth, it’s not as if teeth could not be measured. And as I already wrote, jaw morphology is related to tooth morphology. Animals don’t have the same teeth sticking out of completely different jaws or vice versa.

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And even then, there seems to still be much variation in tooth shape among different groups of predatory theropods (taking away size)
That’s exactly the point! And those didn’t all feed on the same things or killed the same way, so that makes perfect sense!

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a general ziphodont and recurved morphology very-well implies great dependency on other dinosaurs, but there are still different specifications that might indicate higher reliance on ornithopods in one theropod and sauropods in the other.
I’m not sure what specific adaptions of the jaws are necessary for ornithopod prey. They seem like something theropods with various big-game specializations could bring down without problems, and thus they were likely a common component in the diet of various types of large theropods.
Being efficient at hunting ornithopods is rather a matter of agility. They are not armoured, neither are they particularly large. They provide a good target for a variety of jaw morphologies among theropods.

But yes, ziphodont dinosaurs had variable feeding niches. it would be beyond stupid to claim otherwise, after all the vast majority of theropods has this tooth design. Certain proportions of the teeth indicate great aptitude at cutting and slashing, others rather at shearing and crushing, and from the robusticity and size one can tell how and on what they were most likely used.


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Just as how conical teeth will normally be a heavy indicator of piscivory or feeding on smaller animals (especially if they were very small and consistent, like in the gharial, dolphins, or many ichthyosaurs), more knife-like teeth will be more-so an indicator of greater macrophagy. But that does not make every animal with similar teeth specially-adapted for hunting the same things.
I thought you had understood me…
I’m not talking about something as general as "ziphodont" or "conical". These are so broad categories that they only have an extremely rough potential for identification of diet (if at all), because they can be shaped and used in so many ways.
For example canines of pantherine cats and crocodilians are both conical, but they can still be clearly differentiated based on their lenght and proportions (and the distinction gets blatantly obvious once you look at the whole dentition). Similarly the teeth of Carcharodontosaurus, Tyrannosaurus and machairodontid cats are both technically ziphodont (that means: recurved, labiolingually compressed and serrated), but they still differ to a significant degree in terms of relative size and proportions and were certainly not used the same way.

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I did?
Yes, you did. But you are probably going to tell me it was a typo now ;)
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The Reptile
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blaze, I realize that this kind of dentition has been found outside of mammalia; when I was talking earlier, I was talking about specifically MOLARS, CANINES, AND INCISORS, which in truth are only found in mammals. So what if you found one genus with considerably more specialized dentition for multiple things; that doesn't mean that most archosaurs (because early synapsids are still considered as reptiles) have this kind of arrangement. Archosaurs in general were not particularly advanced compared to modern mammals.

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Twice the size of Ceratosaurus. That makes it more likely to prey on prey of a given large size than Ceratosaurus.

Is an AWD going to be hunting smaller prey than the Indian gharial (which, at its greatest lengths, has been known to near that of the largest salties)? Is deinonychus going to be hunting smaller prey than spinosaurus all the time? Or what about a great white shark and a blue whale? Size has almost no correlation with prey type.

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Depends on how much larger, and this is unrelated to the point you were arguing. Obviously certain functional morphologies are better for killing sauropods than others–that’s what I was saying from the beginning, hence also why you can infer similar diets from similar teeth.

Well in the context that there is a difference between a terrestrial herbivore-based diet and a fish-based diet, then yes, similar-built teeth do indicate similar prey preferences. But then again, there are also many more specific details that differentiate the laterally-compressed teeth of different groups of animals, which in turn can prove a significant difference in actual prey preference (being adapted to hunt herbivorous dinosaurs is one thing, but being specialized in hunting stegosaurids is another).

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If the prey is big, the predator preying on it has to be big as well. Not as big as the prey animal, but size helps.

If a predator is a solitary hunter of gigantic animals, then a large size definitely helps. But if that said predator hunts in groups, then size is not as much of a necessity. Lions have been known attacking elephants and giraffes before, but they are not that large comparably; not at all.

And dromeosaurids too likely hunted larger animals in groups.

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Those are extremely variable in morphology, depending on what the herbivore feeds on, actually. Flat-topped isn’t a good way to describe them.

Herbivorous molars are supposed to act as colliding rugose edges to grind down tough plant matter. Those of carnivores (otherwise called carnassials) are designed for sheering, almost like scissors. Are there any solely-herbivorous mammals that lack a blunt chewing surface on their molars?

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Tooth size also concerns the teeth, it’s not as if teeth could not be measured. And as I already wrote, jaw morphology is related to tooth morphology. Animals don’t have the same teeth sticking out of completely different jaws or vice versa.

Well, this can be true if you think about it very lightly. Teeth can still be superficially similar but still be rooted in a completely differently-built skull. Think about Komodo dragons and allosaurus (in spite of great differences, there are still similarities in tooth anatomy).

Define "same"; of course the teeth of two different individuals of the same animal are going to be erupting from the exact same set of jaws. That is a given. SIMILAR teeth on the other hand can have major differences in regard to how they are arranged, how long they are, and what the anatomy of the tooth-baring bones are as well as other areas of the skull.

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That’s exactly the point! And those didn’t all feed on the same things or killed the same way, so that makes perfect sense!

I thought you said that similar teeth equate to very similar hunting/killing...

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I’m not sure what specific adaptions of the jaws are necessary for ornithopod prey. They seem like something theropods with various big-game specializations could bring down without problems, and thus they were likely a common component in the diet of various types of large theropods.

I kind of half-assed that post; it was just meant to give you an idea of what I am talking about.

But now that I think about it, longer maxillary teeth, a shallower skull, and a less obtuse gape would actually make a theropod more-so capable of killing smaller herbivores than sauropods. So I guess it wasn't a completely ludicrous analogy

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Being efficient at hunting ornithopods is rather a matter of agility. They are not armoured, neither are they particularly large. They provide a good target for a variety of jaw morphologies among theropods.

Well yes, but note what I said. Theropods that would do very well in hunting smaller ornithopods may not be as well adapted for hunting sauropods as allosaurus. This is simply because there are still many other differences that constitute prey type/killing style than just the teeth being knife-like or not.

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For example canines of pantherine cats and crocodilians are both conical, but they can still be clearly differentiated based on their lenght and proportions (and the distinction gets blatantly obvious once you look at the whole dentition).

I do understand you, but I wasn't talking about tooth similarities common in completely different groups of animals (such as crocodilians and felids, which are not only part of completely different orders but are in completely different classes as well) with completely different skull shapes. A common tooth shape among very closely-related animals with very similar skull morphologies would be more-so in the realm of being adapted for hunting the same kinds of things. Cats use the stabbing function of their longest teeth for killing, while crocodiles use it for gripping.

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Similarly the teeth of Carcharodontosaurus, Tyrannosaurus and machairodontid cats are both technically ziphodont (that means: recurved, labiolingually compressed and serrated), but they still differ to a significant degree in terms of relative size and proportions and were certainly not used the same way.

I know, but also note that these animals also, like the previous groups of animals, evolved significantly differed skull features that allow for different functions. Not to mention how none of them coexisted and evolved alongside the same animals to begin with. This would make different prey types and killing methods a given, albeit still they possessed general adaptations for killing large terrestrial animals.
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Jinfengopteryx
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The Reptile
Sep 24 2014, 07:21 AM
blaze, I realize that this kind of dentition has been found outside of mammalia; when I was talking earlier, I was talking about specifically MOLARS, CANINES, AND INCISORS, which in truth are only found in mammals. So what if you found one genus with considerably more specialized dentition for multiple things; that doesn't mean that most archosaurs (because early synapsids are still considered as reptiles) have this kind of arrangement. Archosaurs in general were not particularly advanced compared to modern mammals.
And why exactly is this so important and how does this qualify as proof for the last sentence? Blaze also realizes that there are no molars and such outside of mammalia because something very similar would not be called molar if it is found outside of mammalia. His comment was mostly about your last sentence which needs support.
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blaze
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@The Reptile
I already explained that nothing short of a mammal by definition can have teeth that goes by those names so it becomes a semantic argument with no weight, this then moves into a matter of complexity and specialization, I know that one (or a couple) of exceptions don't prove that in general archosaur dentition is not as specialized as that of mammals but you were making a sweeping generalization and when others proved you wrong instead of accepting that there are exceptions you tried to downplay the complexity of Pakasuchus' dentition using only a semantic argument. Just accept you were wrong there, there is nothing to discuss, everyone knows that mammals generally have more specialized dentition.

Now, synapsids are not reptiles , "reptile" in layman terms and as originally envisioned by Linnaeus is a paraphyletic grouping based on a few external traits. Under modern cladistics synapsids are synapsids, the sister group of reptilia (which has precedent over the name sauropsida).

What do you mean by your last sentence? are you still talking about dentition?
Edited by blaze, Sep 27 2014, 10:18 PM.
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The Reptile
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What is the point here? I have not accepted that I am "wrong" yet because I have still not been presented with anything that indicates that true molars and such were found in any genus of archosaur, or been presented with anything stating how mammals are equally as advanced as sauropsids. As I already said, I have known already (as in, long before this discussion even began) that not all sauropsids had a consistent tooth arrangement (both in terms of size and shape), and I acknowledged that. But I specifically made it clear that I was talking about CARNASSIALS being completely absent in diapsids (carnassials and molariforme teeth are two completely different things). Using one genus (or should I say a few, since there are others out there) to "prove" that all archosaurs were as equally-advanced as mammals due to SIMILAR (but not congruent!) dental features is as incomplete as claiming that quilled and/or partially-feathered dinosaurs are as derived as modern aves just because they possess features that slowly evolved into those that we see in modern birds.

And about synapsids- what should they be scientifically classified as?
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theropod
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He already wrote that; the sister group of sauropsida.
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blaze
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@The Reptile
No one is using Pakasuchus to prove that all archosaurs have equally advanced dentition as modern mammals, you said no non-mammal had carnassials, others showed you Pakasuchus which has dentition so convergent that for all intents and purposes in regards to complexity and function does have them (though you can't call them that) and then you went on to downplay how advanced its dentition is just because you can't call it by the same name.

It seems like such a trivial thing to keep debating about even when everyone agrees some exceptions don't affect the argument that archosaurus in general don't have dentition as specialized as mammals but now you seem have changed it to "mammals are more advanced than archosaurs" and this needs way more support than "mammals have true carnassials" or maybe you always used it for this but we didn't notice (Jinfengopteryx seemed surprised too).

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The Reptile
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Quote:
 
No one is using Pakasuchus to prove that all archosaurs have equally advanced dentition as modern mammals, you said no non-mammal had carnassials, others showed you Pakasuchus which has dentition so convergent that for all intents and purposes in regards to complexity and function does have them (though you can't call them that) and then you went on to downplay how advanced its dentition is just because you can't call it by the same name.

But at the same time I was not talking about convergence! I was talking about true, 100% prime-cut CARNASSIALS. These teeth:

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It seems like such a trivial thing to keep debating about even when everyone agrees some exceptions don't affect the argument that archosaurus in general don't have dentition as specialized as mammals but now you seem have changed it to "mammals are more advanced than archosaurs" and this needs way more support than "mammals have true carnassials" or maybe you always used it for this but we didn't notice (Jinfengopteryx seemed surprised too).

What??? In terms of dental morphology/placement, this very-well holds true. And that is not including features such as nursing and almost exclusive development in a womb as opposed to in an egg (this holds true for all mammals except for monotremes. And yes, I do realize that non-mammals do this as well, but save for the most basal group of extant mammals, all of them employ vivipary).
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blaze
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Forget it, you don't get it. Moving on.

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What??? In terms of dental morphology/placement, this very-well holds true. [...]


That's why I asked if this was still about dentition, your assertion in your last comment reads as if you were talking overall.

Nursing and vivipary are not inherently superior to the way most archosaurs are born and take care of their young if that's what you are trying to say, the exception maybe when living in the water in regards to vivipary as we have evidence that ichthyosaurs, plesiosaurs and mosasaurs were viviparous and there's lots of viviparous sharks.
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theropod
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Mammalian dentitions are also not inherently superior to sauropsid ones. They just constitute a derived state compared to the basal condition of amniotes, and so do reptile dentitions but in very different ways (they merely tend to have less differentiated teeth, that's all).
On could argue that being diphyodont is actually vastly inferior to being polyphyodont, as it evidently imposes major restrictions on the jaw apparatus.
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The Reptile
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Forget it, you don't get it. Moving on.

Telling me to forget it and continuing the conversation? Ingenius!

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Nursing and vivipary are not inherently superior to the way most archosaurs are born and take care of their young if that's what you are trying to say, the exception maybe when living in the water in regards to vivipary as we have evidence that ichthyosaurs, plesiosaurs and mosasaurs were viviparous and there's lots of viviparous sharks.

I know, but egg-laying is still a very primitive trait that only a few groups of reptiles employ(ed). The latter 3 groups that you listed would not be able to lay eggs anyway unless they could walk on land like sea turtles can (smaller plesiosaurs have been depicted as doing such, but I am unsure of the accuracy of this claim), because amniotic eggs cannot be suspended in water like those of fish and amphibians can.

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Mammalian dentitions are also not inherently superior to sauropsid ones. They just constitute a derived state compared to the basal condition of amniotes, and so do reptile dentitions but in very different ways (they merely tend to have less differentiated teeth, that's all).

By "superior" I assume you are talking about functionality? If so, then I agree. The difference is how variably they can be used, as opposed to most archosaurs which, if they even have teeth at all, only had one type for one specific purpose. Mammalian dentition is in no-way superior in that regard, but it does give a wider range of function than what you see in archosaurs.
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theropod
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You do see a very wide range of function in archosaurs. You just don’t usually see pronounced morphological disparities between caniniform and molariform teeth, because they don’t have a need for canines.

Dinosaur dentitions are a lot more complex and varied than you give them credit for though. The molariform teeth of ornithopods for example.
The difference is that they often have a beak in addition to teeth, taking the role of the incisors.
So yeah, their teeth are technically less diversified in the same animals, but their chewing apparata can fulfill just as wide a range of functions.
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ansram
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For equal sized theropods, the most likely fight strategy is to deliver a massive bite to the opponent's head. Whoever delivers the first deadly skull bite will probably win, as it would be very difficult for the adversary to recover from that blow. Assuming equal sized animals, 50-50 would be the ideal outcome for this fight. If Carcha manages the first bite, the T-Rex may still manage to beat Carcha because the first blow may not kill outright due to its slicing teeth. If T-Rex delivers the first bite, Carcha is finished with a crushed skull.
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Spartan
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I agree, this fight should be a typical 50-50.
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