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Carcharodontosaurus saharicus v Tyrannosaurus rex
Topic Started: Jun 8 2012, 05:34 PM (129,972 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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Tyrannosaurs Rex vs Carcharodontosaurus
Edited by Taipan, Apr 24 2015, 10:18 PM.
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Ausar
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So? What does this prove? This is just one genus. And besides, these aren't true molars or canines, just molariforme and caniniforme dentition, which is common in archosaurs.
It proves you wrong. It proves your "carnassials are only present in mammals" statement wrong (even if it's only one taxon). Pakasuchus' molariforms and carnassial teeth are also essentially the same thing (given their appearances and function, which is the same), the only difference is that one is in a mammal, one in a reptile.
Edited by Ausar, Sep 13 2014, 11:20 PM.
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The Reptile
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Nope. It still doesn't. CARNASSIALS are not found in any archosaur taxa at all, and this applies to all reptiles as well. Caniniforme and molariforme teeth can still be found in the skulls of reptiles, but they are still more primitive than any tooth in the mouth of a carnivoran. Crocodiles have both, but does that make them so specialized for sheering as say felids?

They are not the same thing at all
Edited by The Reptile, Sep 13 2014, 11:25 PM.
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Ausar
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The teeth in Pakasuchus are probably some of, if not the most advanced in reptiles, likely more so than in other reptiles supposedly stated to have caniniforms, molariforms, etc. (I currently cannot think of any reptile with teeth like that of Pakasuchus). I don't think it'd be a stretch to say its teeth could rival those of mammals in terms of advanceness and specialization.
Edited by Ausar, Sep 13 2014, 11:48 PM.
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theropod
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Exactly, which is why animals having similar-shaped teeth do not automatically possess all of the ideal hunting characteristics needed for killing large sauropods.
These two don’t have similar tooth design, that’s the point:

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Ceratosaurus’ teeth are pretty different from those of Allosaurus. They are ziphodont, but both proportionately larger and more elongated (maxillary crown height/crown base width ratio of 4.5 vs 3.8 in Allosaurus, and crowns longer than dentary depth versus notedly short ones).
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Not that different. They were still recurved, laterally compressed to an extent, and serrated in spite of the uppermost ones being longer.
You cannot just ignore all the quantitative differences between two things because they resemble each other in a few general characteristics (which I even already noted!). I was referring to actual similarity, not superficial similarity.
Two of the three (all three if you compare it to certain animals) also apply to Tyrannosaurus, would you call it’s teeth similar? And yes, the teeth of Ceratosaurus are compressed more strongly than those of Allosaurus.
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Actually its size is one thing, but its skull and tooth combination is another. A wide gape and ability to tear out large chunks of flesh is what allowed allosaurus to kill sauropods BECAUSE it was going to be much smaller than almost every sauropods that it would be hunting. Small size + lack of specialization =/= a high capacity to kill something so large.
Dude, did you even read what I wrote?
read carefully!
 
[...]a Ceratosaurus isn’t going to be killing "10+ ton" diplodocids simply because it is too small (largest specimen is about the size of a subadult/young adult Allosaurus) and there’s no indication whatsoever that it employed gregarious behaviour.


The reason why in Ceratosaurus we have no reason to believe that it hunted large sauropods, while Allosaurus did, is that it’s tooth and jaw morphology are actually different (these two go together, animals don’t have the same teeth but completely different adaptions of the jaws or vice versa), that it’s smaller, and that we have no indication that it hunted in groups.

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Well no, but primates seem to exercise herbivorous behavior much more-so than carnivorous; they are omnivores, yet they seem to only hunt other vertebrates rarely (and some, like gorillas, NEVER do this)
You are overgeneralizing, and you don’t seem to understand the relevant terms.
You can mostly eat plants, that doesn’t mean you are a herbivore. You are a herbivore if you only eat plants. If you eat plants and meat, like humans, or chimpanzees, or baboons, then you are an omnivore. Chimpanzees and baboons prey on other vertebrates regularly, and humans certainly do. These primates are not herbivores. Period.
That gorillas (or Paranthropus) are herbivores doesn’t help your point. Rather they support mine, those are examples of what primates with an actual specialization for herbivory look like.
Humans on the other hand are an example for Adaptions for a generalized diet, albeit with somewhat weakly developed jaws due to out use of extraoral mechanical and chemical food processing before digestion.
Edited by theropod, Sep 14 2014, 12:00 AM.
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The Reptile
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Ausar
Sep 13 2014, 11:35 PM
The teeth in Pakasuchus are probably some of, if not the most advanced in reptiles, likely more so than in other reptiles supposedly stated to have caniniforms, molariforms, etc. (I currently cannot think of any reptile with teeth like that of Pakasuchus). I don't think it'd be a stretch to say its teeth could rival those of mammals in terms of advanceness and specialization.
Because they can't, unless there is a good amount of real conclusive evidence that indicates that they were evolved similarly to those of mammals. And frankly, you said it yourself that, even if its teeth were more differentiated than those of most reptiles, that doesn't necessarily make them comparable to mammals. Where are the real fossils of its teeth? Because if you observe those of mammals thoroughly, you can clearly deduce that there are specialized chewing surfaces present, which are absent in the majority of more primitive groups of animals.

That still does not prove me wrong at all

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You cannot just ignore all the quantitative differences between two things because they resemble each other in a few general characteristics (which I even already noted!). I was referring to actual similarity, not superficial similarity.

So in order to be specialized in preying on a certain kind of animal, you must have an IDENTICAL anatomy? That doesn't make sense, because that is untrue

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Two of the three (all three if you compare it to certain animals) also apply to Tyrannosaurus, would you call it’s teeth similar? And yes, the teeth of Ceratosaurus are compressed more strongly than those of Allosaurus.

Actually, they weren't. Allosaur teeth were more narrow; those of ceratosaurus were shaped like a tear drop in cross-section if descriptions are accurate. I may not have searched long and hard enough to find a direct comparison of the two cross-sectionally, so I apologize for the crudity.

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The reason why in Ceratosaurus we have no reason to believe that it hunted large sauropods, while Allosaurus did, is that it’s tooth and jaw morphology are actually different (these two go together, animals don’t have the same teeth but completely different adaptions of the jaws or vice versa), that it’s smaller, and that we have no indication that it hunted in groups.

As I said, creatures do not need to have congruent features to be capable of hunting the same things; they simply need to have similar features. That is like claiming that tyrannosaurids could not crush because their teeth were recurved, serrated, and only semi-conical; it simply does not make sense.

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You can mostly eat plants, that doesn’t mean you are a herbivore. You are a herbivore if you only eat plants. If you eat plants and meat, like humans, or chimpanzees, or baboons, then you are an omnivore. Chimpanzees and baboons prey on other vertebrates regularly, and humans certainly do. These primates are not herbivores. Period.

I know, but that doesn't mean that they won't eat plant matter as a primary food source, now does it?
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Jinfengopteryx
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Sep 14 2014, 02:07 AM
Ausar
Sep 13 2014, 11:35 PM
The teeth in Pakasuchus are probably some of, if not the most advanced in reptiles, likely more so than in other reptiles supposedly stated to have caniniforms, molariforms, etc. (I currently cannot think of any reptile with teeth like that of Pakasuchus). I don't think it'd be a stretch to say its teeth could rival those of mammals in terms of advanceness and specialization.
Because they can't, unless there is a good amount of real conclusive evidence that indicates that they were evolved similarly to those of mammals. And frankly, you said it yourself that, even if its teeth were more differentiated than those of most reptiles, that doesn't necessarily make them comparable to mammals. Where are the real fossils of its teeth? Because if you observe those of mammals thoroughly, you can clearly deduce that there are specialized chewing surfaces present, which are absent in the majority of more primitive groups of animals.
I suggest looking at what Ausar cited:
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In particular, there were molar-like teeth that met together, providing two parallel shearing edges to slice food, just like those of a modern carnivore.
Or this:
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O'Connor is correct in saying that this is a croc trying hard to be a mammal,
The article said explicitly that the niche of the animal and the function of the teeth were comparable to that of mammals.
And here something from the paper:
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The complex morphology and high degree of occlusal precision of the cheek teeth in Pakasuchus shows a level of sophistication otherwise seen only in mammals.
http://www.oucom.ohiou.edu/dbms-oconnor/PDFs/OConnor_et_al_2010_mammal_like_crocodyliforms.pdf
They used microCT scans to study the teeth, so I believe we can say that there is some support for this statement. If we can only see this in mammals, I believe "comparable" is a good description. They would otherwise have written something like "intermediate between mammals and reptiles".
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theropod
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So in order to be specialized in preying on a certain kind of animal, you must have an IDENTICAL anatomy? That doesn't make sense, because that is untrue
You mean "the same kind of animal", and yes, if your teeth truly do the same they should be expected to be very similar. If there are differences between them (size, proportions, edge morphology), these can be important correlates of a different feeding stype and jaw morphology, as they are in Ceratosaurus. Notably (and this has been noted in the literature too), Ceratosaurus likely relied more on traditional biting than striking and slashing, hence why its teeth are so long to be better at puncturing in a static bite.

This discussion defies the original meaning of my statement: "yes, actually theropods with similar teeth likely had similar feeding style and prey preferences"

That means if two theropods have an analogous tooth design, they probably used it for the same thing. The teeth are definitely an important clue as to what the animals were best suited to kill, and how they did it. And they can not be regarded in isolation.
It was you who brought up Ceratosaurus and took this out of context.

Lumping everything that’s technically ziphodont into one category is definitely BS.
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Actually, they weren't. Allosaur teeth were more narrow; those of ceratosaurus were shaped like a tear drop in cross-section if descriptions are accurate. I may not have searched long and hard enough to find a direct comparison of the two cross-sectionally, so I apologize for the crudity.
Ceratosaurid teeth are more compressed, Check Smith et al 2005. and Bakker 1998. Maxillary teeth of C. nasicornis and dentisulcatus have an even narrower shape. This alone isn’t the determining thing though, primarily that they are so much taller-crowned and bigger in absolute terms, suggesting a different use.

And no, "allosaur teeth" are not all the same either, and neither were the ways they attacked or what they preyed on. These animals aren’t all the same.
Of course tooth and jaw design always have to be considered together, they are not separable.

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As I said, creatures do not need to have congruent features to be capable of hunting the same things
I never claimed so!

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they simply need to have similar features
No, they don’t. Sometimes completely opposite features are both suited for performing a the same task. But if their features are similar (and not just on a very general level, such as being ziphodont, but on a more detailed one, such as being of a certain approximate height in relation to skull size and of specific proportions), that’s an indicator that they actually worked the same way (and thus likely for the same thing too).
Of course we can draw more generalized analogies (such as between carnosaurs and certain sharks, based on that they both use their dentition for slicing), but then we have to be careful and not conclude too much (nobody would imply that because both used their teeth for slicing all carnosaurs must have preyed on the same prey a shark takes).

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That is like claiming that tyrannosaurids could not crush because their teeth were recurved, serrated, and only semi-conical; it simply does not make sense.
Exactly, it does not. That’s the point.
Based on your logic ("they are ziphodont, so they are all the same"), it would have to be true. Get what I mean?

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I know, but that doesn't mean that they won't eat plant matter as a primary food source, now does it?
That’s besides the point. You were the one who claimed that humans were "clearly designed for herbivory". Well, turns out we aren’t, we are designed for omnivory.



REFERENCES:
Bakker, Robert: Brontosaur killers: Late Jurassic allosaurids as sabre-tooth cat analogues. Gaia, vol. 15 (1998); pp. 145-158
Smith, Joshua; Vann, David; Dodson, Peter: Dental Morphology and Variation in Theropod Dinosaurs: Implications for the Taxonomic Identification of Isolated Teeth. The Anatomical Record, vol. 285 (2005); A; pp. 699-736
Edited by theropod, Sep 14 2014, 03:17 AM.
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The Reptile
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Jinfengopteryx, I am not denying that they were not similar to that of mammals, just that the trait of varied dentition shapes did not evolve as a general feature in reptiles, whereas in mammals it is quite so.

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You mean "the same kind of animal", and yes, if your teeth truly do the same they should be expected to be very similar. If there are differences between them (size, proportions, edge morphology), these can be important correlates of a different feeding stype and jaw morphology, as they are in Ceratosaurus. Notably (and this has been noted in the literature too), Ceratosaurus likely relied more on traditional biting than striking and slashing, hence why its teeth are so long to be better at puncturing in a static bite.

I said that there being a similarity in prey type does not always guarantee a similarity in feeding characteristics. I admit that I should not have said "specialized" in my last post; what I meant was that predators with differently-shaped dentition from another predator can rely heavily on prey that the latter is specialized in; the difference being in how they killed it. Sure, some predators like allosaurs will be more proficient at killing sauropods than something that is designed more for "traditional" biting like ceratosaurus (I actually do not disagree with your claim here, as it is perfectly logical), but that does not mean that ceratosaurus could not hunt sauropods.

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That means if two theropods have an analogous tooth design, they probably used it for the same thing. The teeth are definitely an important clue as to what the animals were best suited to kill, and how they did it. And they can not be regarded in isolation.
It was you who brought up Ceratosaurus and took this out of context.

When? I am sorry, I just have little recollection of what I said earlier because so much else was said in between.

Killing style can definitely be deduced from tooth and skull shape, but identifying prey type only goes to a certain degree here. Crocodiles have teeth and skulls (especially some of the more longistrine species) that were for the most part evolved to grip and crush smaller animals, particularly fish. Yet they will still often hunt impala and such without hassle.

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Lumping everything that’s technically ziphodont into one category is definitely BS.

Thank you.......

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Ceratosaurid teeth are more compressed, Check Smith et al 2005. and Bakker 1998. Maxillary teeth of C. nasicornis and dentisulcatus have an even narrower shape. This alone isn’t the determining thing though, primarily that they are so much taller-crowned and bigger in absolute terms, suggesting a different use.

Hmm, well then what I read about them being more robust than those of allosaurs was probably very wrong, nor have I even observed an actual ceratosaur tooth before in great depth alongside that of an allosaur.

But yes, there should be no denying that a function of deep and powerful penetration into a prey's back is probably what it employed most of all. I do not disagree with this at all

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And no, "allosaur teeth" are not all the same either, and neither were the ways they attacked or what they preyed on. These animals aren’t all the same.

That is like saying that crocodilian teeth are different so they had vastly different uses (in spite of there being clear variations in function, they seem too insignificant for one to bat an eye at their differences as "evidence" for a considerably different lifestyle).

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No, they don’t. Sometimes completely opposite features are both suited for performing a the same task. But if their features are similar (and not just on a very general level, such as being ziphodont, but on a more detailed one, such as being of a certain approximate height in relation to skull size and of specific proportions), that’s an indicator that they actually worked the same way (and thus likely for the same thing too).

I know this.

Wow, I just realized that I said something that is complete BS in the post that you were quoting here... I just had a small brain slip-up and did NOT mean to say that animals needed similar features to be able to hunt the same things, just that similar features are evolutionary imperative for them to specialize in hunting or consuming the same things (this applies to omnivores and herbivores as well, not just carnivores)

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Based on your logic ("they are ziphodont, so they are all the same"), it would have to be true. Get what I mean?

I'm confused... I never said that being ziphodont automatically meant that they were completely congruent/identical in both morphology and function. Tooth shape has a lot to do with prey specialization, but certainly not a predator's actual ability to kill something successfully (whether or not it was done with efficiency does not matter here. THAT has a lot to do with specialization/aptitude, not ability). For example, an alligator will most likely be able to crush a turtle with greater efficiency than an American crocodile, but that does not mean the latter cannot kill turtles, just that an alligator has a much more favorable anatomy for it.
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theropod
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I said that there being a similarity in prey type does not always guarantee a similarity in feeding characteristics. I admit that I should not have said "specialized" in my last post; what I meant was that predators with differently-shaped dentition from another predator can rely heavily on prey that the latter is specialized in; the difference being in how they killed it. Sure, some predators like allosaurs will be more proficient at killing sauropods than something that is designed more for "traditional" biting like ceratosaurus (I actually do not disagree with your claim here, as it is perfectly logical), but that does not mean that ceratosaurus could not hunt sauropods.
Well, the funny thing is that you used the exact opposite claim (that Ceratosaurus did not hunt the same prey as Allosaurus) earlier, to support your notion that animals with supposedly similar dentition are not built to do the same…

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When? I am sorry, I just have little recollection of what I said earlier because so much else was said in between.
You just forgot that part? I don”t believe that, I’m sorry.
This was your example: "Are ceratosaurs going to be killing diplodocids within the 10+ ton range just because their teeth were recurved and serrated? Probably not if they did not possess the same jaw-opening capabilities as allosaurus and its closest kin."

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Killing style can definitely be deduced from tooth and skull shape, but identifying prey type only goes to a certain degree here.
Then, certain killing styles are indicative of prey type and vice versa. And among the most solid indicators of killing style, especially among theropods are its skull and teeth. So if the dentitions are very similar that indicates that they killed similarly and were best at similar things.
You can only apply that to prey favouring certain morphologies of course, any of these could kill a human or a Dryosaurus with ease, regardless of jaw and tooth morphology, but then again, that they have strong skulls and necks and ziphodont teeth itself generally implies feeding on large prey, different kinds depending on the exact morphology of these teeth.

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Hmm, well then what I read about them being more robust than those of allosaurs was probably very wrong, nor have I even observed an actual ceratosaur tooth before in great depth alongside that of an allosaur.
Where have you read that?

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But yes, there should be no denying that a function of deep and powerful penetration into a prey's back is probably what it employed most of all. I do not disagree with this at all
Disagree with what? You are making up your own hypotheses and then making it look as if I had suggested them!

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That is like saying that crocodilian teeth are different so they had vastly different uses (in spite of there being clear variations in function, they seem too insignificant for one to bat an eye at their differences as "evidence" for a considerably different lifestyle).
Are you telling me that the dentitions of a saltie, an alligator and a gharial don’t show significant dietary differences?

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Wow, I just realized that I said something that is complete BS in the post that you were quoting here... I just had a small brain slip-up and did NOT mean to say that animals needed similar features to be able to hunt the same things, just that similar features are evolutionary imperative for them to specialize in hunting or consuming the same things (this applies to omnivores and herbivores as well, not just carnivores)
No, it’s not. A komodo dragon for example kills a buffalo by severing its leg tendons and letting it bleed to death, a lion kills a buffalo by squeezing its trachea and simultaneously wrestling with it. There are different ways for animals to do something, and an exclusiong can indeed not be made (if at all) without knowledge of its complete osteology.
The point is that similarity in certain features, such as teeth, is still generally indicative of similar prey type among carnivores.

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I'm confused... I never said that being ziphodont automatically meant that they were completely congruent/identical in both morphology and function.

You wrote this:
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Not that different. They were still recurved, laterally compressed to an extent, and serrated in spite of the uppermost ones being longer.

In relation to your argument about Ceratosaurus’ ecomorphology which you appear to have forgotten completely.

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Tooth shape has a lot to do with prey specialization, but certainly not a predator's actual ability to kill something successfully (whether or not it was done with efficiency does not matter here.
Obviously how well-suited something is for something does have a lot to do with whether it can do it. A T. rex would never be an efficient hunter of rodents, regardless of its anatomical capability of killing them easily.

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THAT has a lot to do with specialization/aptitude, not ability). For example, an alligator will most likely be able to crush a turtle with greater efficiency than an American crocodile, but that does not mean the latter cannot kill turtles, just that an alligator has a much more favorable anatomy for it.
Well, I suspect a gharial would not be able to kill a turtle, but both have conical teeth.
If you want to tell they are suited for the same thing you simply have to make closer comparisons between them than that, that’s why your Ceratosaurus example doesn’t work. That does not by any means reduce the relevance of tooth morphology for the predatory capabilities of an animal, it just means you have to look and contrast more carefully.
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Ausar
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Jinfengopteryx, I am not denying that they were not similar to that of mammals, just that the trait of varied dentition shapes did not evolve as a general feature in reptiles, whereas in mammals it is quite so.
I'm not Jinfengopteryx, but since I'm part of this as well, I know that this kind of dentition is rare in sauropsids, but I was merely pointing out that Pakasuchus' molariforms in particular were insanely similar to the carnassials of mammals (evidence of it was aformentionally posted), thus this tooth morphology is not exclusive to mammals.
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Well, the funny thing is that you used the exact opposite claim (that Ceratosaurus did not hunt the same prey as Allosaurus) earlier, to support your notion that animals with supposedly similar dentition are not built to do the same…

I was talking about what animals it was actually evolved to hunt. If I said something that seemed to have indicated otherwise, I apologize. But that is not what I meant at all; typos are a thing that one needs to get used to in today's world. See one of my responses below that justifies my position.

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You just forgot that part? I don”t believe that, I’m sorry.

Doubt what you want, but doubting something that was mental on my part will never be proven unless I admit it (it is in MY mind only)! Don't get sucked into the forum doubting thing; once you are in, you can never get out!

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This was your example: "Are ceratosaurs going to be killing diplodocids within the 10+ ton range just because their teeth were recurved and serrated? Probably not if they did not possess the same jaw-opening capabilities as allosaurus and its closest kin."

BOLDED

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Then, certain killing styles are indicative of prey type and vice versa. And among the most solid indicators of killing style, especially among theropods are its skull and teeth. So if the dentitions are very similar that indicates that they killed similarly and were best at similar things.

This can sometimes hold true, but not always. Here you seem to be referring to completely identical tooth and skull morphologies, in which case I agree that two theropods (closely-related or not) with almost 100% identical feeding features will both specialize in the same prey type and probably kill the same way.


But the way I look at it is that, even teeth that are ziphodont, conical, flat, you name it still have large variations that constitute different prey preferences and killing tactics.

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You can only apply that to prey favouring certain morphologies of course, any of these could kill a human or a Dryosaurus with ease, regardless of jaw and tooth morphology, but then again, that they have strong skulls and necks and ziphodont teeth itself generally implies feeding on large prey, different kinds depending on the exact morphology of these teeth.

Hmm. I think I can see what you are saying, but not exactly. There really is no other response I can give to this quote aside from asking for a bit of a summary as to what you are saying here.

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Disagree with what? You are making up your own hypotheses and then making it look as if I had suggested them!

I am? You stated that ceratosaurus probably killed very differently from allosaurus (I agree with this thought), and I must have confused that with how I thought it killed specifically to form a sentence that made it seem as if you said it before. I am sorry for that.

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Are you telling me that the dentitions of a saltie, an alligator and a gharial don’t show significant dietary differences?

Sure, you have differences in robusticity for both the teeth and the skulls, but they still tell the same general story: specialization in small animals and most specifically fish.

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No, it’s not. A komodo dragon for example kills a buffalo by severing its leg tendons and letting it bleed to death, a lion kills a buffalo by squeezing its trachea and simultaneously wrestling with it. There are different ways for animals to do something, and an exclusiong can indeed not be made (if at all) without knowledge of its complete osteology.

This is yet again one of those typo situations on my part. The post came out looking like I was proposing that predators of all classes and groupings were in need of similar skull and tooth morphology to hunt the same things, correct? Well I did not mean to say this; not at all. What I meant to say was that a similar killing style for bringing down similar animals relies on alike characteristics (this especially holds true if both predators that are being "compared" are related to an at least small extent, such as if they were both theropods).

Of course lions and Komodo dragons will often hunt buffalo (albeit different species of buffalo, but still buffalo nonetheless), and of course they have vastly different skulls, teeth, and ways that they hunt/kill, but note that they are not closely related at all and as such developed different anatomies.

Edited by The Reptile, Sep 20 2014, 12:17 PM.
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The Reptile
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You wrote this:
In relation to your argument about Ceratosaurus’ ecomorphology which you appear to have forgotten completely.

Saying that they were not all that different does not mean I considered them identical...

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Obviously how well-suited something is for something does have a lot to do with whether it can do it. A T. rex would never be an efficient hunter of rodents, regardless of its anatomical capability of killing them easily.

As I said, eliminate the efficiency. A tyrannosaurus could still kill a large rat effortlessly if it was able to pick it up in the first place. The only hindrance is that its skull was so large and the rat was so tiny by comparison.

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but I was merely pointing out that Pakasuchus' molariforms in particular were insanely similar to the carnassials of mammals (evidence of it was aformentionally posted),

I know, and I don't disagree that differentiated dentition is still present in reptiles. In fact, I have known about pakasuchus for some time now, but that still doesn't eliminate the fact that its teeth were still ultimately more primitive. Crocodiles too have both caniniforme and molariforme dentition, but does that make their teeth as advanced as those of mammals so-to-speak?

The difference is that this kind of dental arrangement is going to be VERY rare in all diapsids in general.

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thus this tooth morphology is not exclusive to mammals.

Scientifically-speaking, it still is. True canines, incisors, and molars (otherwise known as carnassials in most carnivores) evolved in mammals, not diapsids (I am using this term because I do not want to argue about prehistoric synapsids now, which in general had primitively-mammalian dentition)

The majority of lepidosaurs and archosaurs (as well as the more primitive groups that arose from the stem) still have one general tooth shape, whether it be knife-like, spike-like, flat, bulbous, needle-like, etc.
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blaze
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You are arguing semantics, true canines, incisors and molars (carnassials) are always going to be exclusive to mammals because they were defined that way but that doesn't mean that because convergent dentition can't be called by those names they are necessarily more "primitive".

Molariform and caniform as used in, for example, crocodiles and non-mammalian synapsids, are only broad terms used to classify teeth based on their similarity of function to those in the differentiated dentition of mammals, they do not tell you how advanced the dentition is.

As explained by the authors, the molariform teeth of Pakasuchus are clearly convergent and as advanced as true carnassials.

You have a point that this type in dentition is rare outside of mammals but Pakasuchus was brought up because you originally claimed advanced dentition like that was exclusive to mammals, such generalized and broad claims are proven false as long as there is single exception (read up on propositions).
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theropod
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This was your example: "Are ceratosaurs going to be killing diplodocids within the 10+ ton range just because their teeth were recurved and serrated? Probably not if they did not possess the same jaw-opening capabilities as allosaurus and its closest kin."

BOLDED
And as I wrote, that’s because Ceratosaurus was not large enough, and there’s no indication of gregarious behaviour. And it may not be as well-adapted for sauropod prey due to its teeth and jaws.
That doesn’t refute the notion that similar dentitions are generally correlated with similar diets.

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But the way I look at it is that, even teeth that are ziphodont, conical, flat, you name it still have large variations that constitute different prey preferences and killing tactics.
Yes, they do. These are broad categories (what do you mean by "flat" though?), there is still a lot of variation within them, and it is important to keep that in mind when evaluating the relevance and meaning of an analogy.

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This can sometimes hold true, but not always. Here you seem to be referring to completely identical tooth and skull morphologies, in which case I agree that two theropods (closely-related or not) with almost 100% identical feeding features will both specialize in the same prey type and probably kill the same way.
The more similar the teeth, the more similar the dietary preferences and killing style. How similar you want it is entirely up to you, but you have to account for that if you want to rely on examples.
This was the question I answered originally: "Were similar theropods as well adapted for killing big animals because they had similar dentition"
If they have similar dentition that implies the dentition was good at similar things. Also, similar dentition rarely comes alone, but rather in combination with similar features of the jaws as well. So yes, if similar theropods had similar dentitions that means they were well-suited for similar things. Of course you can replace similar with every term you want here, take "the same" if you like it better.

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Hmm. I think I can see what you are saying, but not exactly. There really is no other response I can give to this quote aside from asking for a bit of a summary as to what you are saying here.
I hope the above is good enough.

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I am? You stated that ceratosaurus probably killed very differently from allosaurus (I agree with this thought), and I must have confused that with how I thought it killed specifically to form a sentence that made it seem as if you said it before. I am sorry for that.
That’s what i meant, you were talking of "deep penetration" into something’s back, I don’t think I’ve talked about that thing so it’s nothing you can agree with me on.
I think Ceratosaurus would have preferred biting the flanks or belly, or, if the girth of these was too high, the throat.

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Sure, you have differences in robusticity for both the teeth and the skulls, but they still tell the same general story: specialization in small animals and most specifically fish.
Yes, but only on a very general level. On the same level, sure, all theropods with ziphodont teeth are similar too. I was talking about far more specific similarities, indicated by far more specific similarities between their teeth.

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Saying that they were not all that different does not mean I considered them identical...
Well, they were different enough to likely have different diets and prey preferences, but you were arguing that the latter constituted some sort of exception while in animals with this degree of difference in the morphology of the dentition you will commonly find this.

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As I said, eliminate the efficiency. A tyrannosaurus could still kill a large rat effortlessly if it was able to pick it up in the first place. The only hindrance is that its skull was so large and the rat was so tiny by comparison.
Exactly, it could not effectively catch the rat in the first place. That, of course, has to do with its dentition and skull.
If it’s skull was the size and built of a Coelophysis’ its chances of succeeding in catching a rat would be far higher, i.e. it would be better at it.

But it isn’t built for it, as its teeth alone can easily tell you.
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The Reptile
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Molariform and caniform as used in, for example, crocodiles and non-mammalian synapsids, are only broad terms used to classify teeth based on their similarity of function to those in the differentiated dentition of mammals, they do not tell you how advanced the dentition is.

Being molariforme or caniniforme actually does imply how advanced they were; teeth being described as such usually (note the term "usually") are not much different from one another. Crocodiles can be described as in the possession of both because those in the anterior and posterior of the mouth do show differences in shape and function (those in the front being used for stabbing and gripping and those in the back for crushing) but at the same time are still generally the same type of tooth.

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As explained by the authors, the molariform teeth of Pakasuchus are clearly convergent and as advanced as true carnassials.

Of course they were convergent, but that does not make them equally advanced. Not in the least bit.

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You have a point that this type in dentition is rare outside of mammals but Pakasuchus was brought up because you originally claimed advanced dentition like that was exclusive to mammals, such generalized and broad claims are proven false as long as there is single exception (read up on propositions).

Read this that I posted earlier:

"Nope. It still doesn't. CARNASSIALS are not found in any archosaur taxa at all, and this applies to all reptiles as well. Caniniforme and molariforme teeth can still be found in the skulls of reptiles, but they are still more primitive than any tooth in the mouth of a carnivoran. Crocodiles have both, but does that make them so specialized for sheering as say felids?"

I was talking about true molars and canines, not what is otherwise found in many reptile groups. It is possible that the variations in the teeth of synapsids (includes mammals and mammal-like reptiles) were an off-shoot of tiny variations in the mouths of more primitive groups of vertebrates. Of course synapsids did not evolve from diapsids, but they are fundamentally more advanced. The majority of predatory archosaurs, based on current knowledge, seem to have been specialized in one sort of hunting type, and as such many will have a dental anatomy where the only variations are size (teeth and jaws that are specialized for certain circumstances are common in different groups of dinosaurs and crocodylomorphs; you will find much variation depending between different species, but otherwise there is not much variation in a single species tooth-wise.

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And as I wrote, that’s because Ceratosaurus was not large enough, and there’s no indication of gregarious behaviour. And it may not be as well-adapted for sauropod prey due to its teeth and jaws.

Allosaurus wasn't particularly large either, yet it would still most likely have much less trouble bringing down a large sauropod than a spinosaurid or crocodilian much larger than it.

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?)

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(what do you mean by "flat" though?)

Flat-topped, like the molars of mammalian herbivores

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If they have similar dentition that implies the dentition was good at similar things. Also, similar dentition rarely comes alone, but rather in combination with similar features of the jaws as well. So yes, if similar theropods had similar dentitions that means they were well-suited for similar things. Of course you can replace similar with every term you want here, take "the same" if you like it better.

OK, thank you for clearing that up.

But having similar-shaped dentition is one thing; tooth size and the physiology/morphology of the skull/jaws is also a factor to consider. And even then, there seems to still be much variation in tooth shape among different groups of predatory theropods (taking away size); 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.

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Yes, but only on a very general level. On the same level, sure, all theropods with ziphodont teeth are similar too. I was talking about far more specific similarities, indicated by far more specific similarities between their teeth.

Well then there is nothing that I can argue against, because there ARE vivid differences that indicate more specific feeding intricacies among crocodilians.

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.

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but you were arguing that the latter constituted some sort of exception while in animals with this degree of difference in the morphology of the dentition you will commonly find this.

I did?
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