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Spinosaurus aegyptiacus v Tyrannosaurus rex
Topic Started: Jan 7 2012, 02:16 AM (459,146 Views)
Wolf Eagle
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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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Spinosaurus aegyptiacus
Spinosaurus is a genus of theropod dinosaur which lived in what is now North Africa, from the lower Albian to lower Cenomanian stages of the Cretaceous period, about 112 to 97 million years ago. Spinosaurus may be the largest of all known carnivorous dinosaurs, even larger than Tyrannosaurus and Giganotosaurus. Estimates published in 2005 and 2007 suggest that it was 12.6 to 18 metres (41 to 59 ft) in length and 7 to 20.9 tonnes (7.7 to 23.0 short tons) in weight. The skull of Spinosaurus was long and narrow like that of a modern crocodilian. Spinosaurus is thought to have eaten fish; evidence suggests that it lived both on land and in water like a modern crocodilian. The distinctive spines of Spinosaurus, which were long extensions of the vertebrae, grew to at least 1.65 meters (5.4 ft) long and were likely to have had skin connecting them, forming a sail-like structure, although some authors have suggested that the spines were covered in fat and formed a hump. Multiple functions have been put forward for this structure, including thermoregulation and display. Dal Sasso et al. (2005) assumed that Spinosaurus and Suchomimus had the same body proportions in relation to their skull lengths, and thereby calculated that Spinosaurus was 16 to 18 meters (52 to 59 ft) in length and 7 to 9 tonnes (7.7 to 9.9 short tons) in weight. The Dal Sasso et al. estimates were criticized because the skull length estimate was uncertain, and (assuming that body mass increases as the cube of body length) scaling Suchomimus which was 11 meters (36 ft) long and 3.8 tonnes (4.2 short tons) in mass to the range of estimated lengths of Spinosaurus would produce an estimated body mass of 11.7 to 16.7 tonnes (12.9 to 18.4 short tons).

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Edited by Taipan, Apr 24 2015, 10:10 PM.
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retic
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theropod
Apr 28 2014, 08:10 PM
retic
Apr 28 2014, 08:19 AM
theropod
Apr 28 2014, 02:42 AM
Spinosaurus does not have a skull similar to a false gharial. Its snout is comparable in width (in relative terms of course) but far deeper.
And the false gharial is an excellent example of how bite force isn’t very relevant–because false gharials produce respectable ones-in fact we get more than 1.2t for a 1t specimen based on Erickson et al. 2012, and the maximum values measured for T. schlegelii were among the highest in the whole study.
Unless we want to scale up its bite force based on false gharials (which would result in bite forces easily as high as, or higher than, that of T. rex!), it may not be so wise to always use them as an argument.
Spinosaurus has a few small things in common–conical teeth and an elongated snout–but there are many differences, which essentially mean predator-prey ratios cannot be just projected from one onto the other.
Spinosaurids may have been crocodile-mimics, that doesn’t mean they are also functional crocodile analogues.

Not sure, do they kill conspecifics, like other crocodilians do? At least I know they kill humans and deer, they are not limited to small fish.
Anyway, I don’t think Tomistoma has the option of killing a similar-sized animal by slamming it to the ground, puncturing its lung with its claws, or by stepping onto it.

Also that Tyrannosaurus "has to fight other members of its species" isn’t an argument proving that Spinosaurus’ bite would be incapable of causing damage on it. that’s like saying "a wolf has to fight other wolves, so why should a cougar be able to harm it?".

In certain reagions, Spinosaurus’ bite could be very dangerous. In others, not that much.
bite force might not be very relevant, but having serrated teeth is. tyrannosaurus not only has a strong bite, but it has serrations. i'm not saying spinosaurus can't kill tyrannosaurus, just that it will be highly unlikely that it will be killing it with its bite. your wolf and cougar example doesn't make sense since cougars have been known to kill large prey such as moose with their bite, while spinosaurus has the adaptations (in terms of biting) of an animal that hunts fish and dinosaurs significantly smaller than itself, such as a slender snout and conical teeth.
T. rex serrations (again): They don’t act like normal serrations, their function is more similar to an unserrated blade (a fairly blunt one that is). Source→

• I agree it is unlikely it will be doing it with its bite, most likely it will use its sheer size, strenght and its forelimbs (although I think it will also use its jaws, but as gripping tools).

• Yes, a cougar does kill large animals. But if it was just a fossil rostrum and the cat family was poorly known as a whole, would we know that? Its jaws are pretty tiny and it has a set of conical teeth in front. Chances are that cats would also be considered primarily piscivorous.
Cougars rely strongly on behavioural adaptions when killing large animals–they place a bite to the throat, nape or skull to kill it, much unlike animals with jaws built to be damaging (theropods, wolves, hyaenas, sharks, monitor lizards).
Regarding functional anatomy, spinosaurus would have had the same capability. Of course, it’s doubtful whether its brain was sophisticated enough for these kinds of attack methods. Hence what I wrote, in certain places, Spinosaurus’ jaws could be very dangerous.

Considering it likely has the longest (and thickest) tooth of any theropod in its jaw, it is not inconceivable it would have managed to pierce deep enough to puncture the spinal chord with a bite, and it certainly wouldn’t be beyond those jaw’s capabilities to clamp down on a windpipe.
i guess it is possible that the bite of spinosaurus could inflict some damage to a sizable opponent, though i think it would need some luck in order to do so. the modern animals with the most comparable jaws to spinosaurus seem ineffective at taking big prey ( relative to their size ). i know comparing the skull of spinosaurus to modern animals may not seem right to you, but modern animals are all we have.
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theropod
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@jinfen: Yes, that was Abler’s hypothesis (if it was really this work that made the claim so popular I find it strange only that part tuck with the people who read it…). But frankly, I highly doubt any of the people who still believe in this matter are actually aware of the paper. At least none I ever discussed it with brought it up.
The people who read the actual papers on the other hand certainly know that the analogy has been revised, rendering the hypothesis outdated.

That T. rex’ bite may have been septic isn’t ruled out by that, it simply is nothing special, because almost all carnivores can have septic bites. And besides, it is nothing that would be of much help in a fight, since succumbing to an infection (completely unlike envenomation, like in komodo dragons) from a bite will take days.
Its funny how it is often the people who cite the septic-bite-theory for T. rex as an advantage who will also come and claim animals like oras were terribly slow, ineffective killers.
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TheMechaBaryonyx789
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retic
May 1 2014, 06:19 AM
theropod
Apr 28 2014, 08:10 PM
retic
Apr 28 2014, 08:19 AM
theropod
Apr 28 2014, 02:42 AM
Spinosaurus does not have a skull similar to a false gharial. Its snout is comparable in width (in relative terms of course) but far deeper.
And the false gharial is an excellent example of how bite force isn’t very relevant–because false gharials produce respectable ones-in fact we get more than 1.2t for a 1t specimen based on Erickson et al. 2012, and the maximum values measured for T. schlegelii were among the highest in the whole study.
Unless we want to scale up its bite force based on false gharials (which would result in bite forces easily as high as, or higher than, that of T. rex!), it may not be so wise to always use them as an argument.
Spinosaurus has a few small things in common–conical teeth and an elongated snout–but there are many differences, which essentially mean predator-prey ratios cannot be just projected from one onto the other.
Spinosaurids may have been crocodile-mimics, that doesn’t mean they are also functional crocodile analogues.

Not sure, do they kill conspecifics, like other crocodilians do? At least I know they kill humans and deer, they are not limited to small fish.
Anyway, I don’t think Tomistoma has the option of killing a similar-sized animal by slamming it to the ground, puncturing its lung with its claws, or by stepping onto it.

Also that Tyrannosaurus "has to fight other members of its species" isn’t an argument proving that Spinosaurus’ bite would be incapable of causing damage on it. that’s like saying "a wolf has to fight other wolves, so why should a cougar be able to harm it?".

In certain reagions, Spinosaurus’ bite could be very dangerous. In others, not that much.
bite force might not be very relevant, but having serrated teeth is. tyrannosaurus not only has a strong bite, but it has serrations. i'm not saying spinosaurus can't kill tyrannosaurus, just that it will be highly unlikely that it will be killing it with its bite. your wolf and cougar example doesn't make sense since cougars have been known to kill large prey such as moose with their bite, while spinosaurus has the adaptations (in terms of biting) of an animal that hunts fish and dinosaurs significantly smaller than itself, such as a slender snout and conical teeth.
T. rex serrations (again): They don’t act like normal serrations, their function is more similar to an unserrated blade (a fairly blunt one that is). Source→

• I agree it is unlikely it will be doing it with its bite, most likely it will use its sheer size, strenght and its forelimbs (although I think it will also use its jaws, but as gripping tools).

• Yes, a cougar does kill large animals. But if it was just a fossil rostrum and the cat family was poorly known as a whole, would we know that? Its jaws are pretty tiny and it has a set of conical teeth in front. Chances are that cats would also be considered primarily piscivorous.
Cougars rely strongly on behavioural adaptions when killing large animals–they place a bite to the throat, nape or skull to kill it, much unlike animals with jaws built to be damaging (theropods, wolves, hyaenas, sharks, monitor lizards).
Regarding functional anatomy, spinosaurus would have had the same capability. Of course, it’s doubtful whether its brain was sophisticated enough for these kinds of attack methods. Hence what I wrote, in certain places, Spinosaurus’ jaws could be very dangerous.

Considering it likely has the longest (and thickest) tooth of any theropod in its jaw, it is not inconceivable it would have managed to pierce deep enough to puncture the spinal chord with a bite, and it certainly wouldn’t be beyond those jaw’s capabilities to clamp down on a windpipe.
i guess it is possible that the bite of spinosaurus could inflict some damage to a sizable opponent, though i think it would need some luck in order to do so. the modern animals with the most comparable jaws to spinosaurus seem ineffective at taking big prey ( relative to their size ). i know comparing the skull of spinosaurus to modern animals may not seem right to you, but modern animals are all we have.
Spinosaurus' bite could inflict damage to a sizeable opponent with ease. You are underestimating these jaws:
Posted Image
Laterally Spinosaurus jaws look pretty devastating. The only unimpressive feature about Spinosaurus' jaws is that they weren't very wide, but this doesn't stop its bite from being powerful.
Just because Spinosaurus' jaws were comparable with fresh-water crocodile's jaws doesn't mean that they had similar killing/fighting capacities. Spinosaurus had some formidable forelimbs and sheer size on its side, and its jaws are overall more impressive than a modern-day fresh-water crocodile's jaws anyway. I personally see Spinosaurus being efficient at tackling sizeable prey.
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theropod
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The snouts of crocodylians are far flatter and more pneumatised than that of Spinosaurus. We are talking about an animal with a relatively deep and very compact snout.

References:
http://www.youtube.com/watch?feature=player_detailpage&v=_bMCSKdgIA4#t=600

http://digimorph.org/specimens/Tomistoma_schlegelii/
http://digimorph.org/specimens/Crocodylus_johnstoni/
Edited by theropod, May 1 2014, 08:48 PM.
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Jinfengopteryx
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theropod
May 1 2014, 06:28 AM
@jinfen: Yes, that was Abler’s hypothesis (if it was really this work that made the claim so popular I find it strange only that part tuck with the people who read it…). But frankly, I highly doubt any of the people who still believe in this matter are actually aware of the paper. At least none I ever discussed it with brought it up.
The people who read the actual papers on the other hand certainly know that the analogy has been revised, rendering the hypothesis outdated.
I was rather referring to what the creators of certain documentaries could have based it on. Of course most people don't read papers, claims in papers only get widespread through either tons of newspaper articles (and their spreading on YouTube), documentaries or books.
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theropod
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I’m not even sure whether the makers of the documentaries themselves were aware of the paper…

Chances are they found some mention of it through some secondary source and picked up on the idea because it sounded good.
Edited by theropod, May 2 2014, 02:27 AM.
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Jinfengopteryx
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I don't think documentaries do that superficial research. If they can hire scientists, they likely also read papers, but change the information a bit, to make it more interesting.
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theropod
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Well, they hire scientists to make statements that they then edit into what they would like them to have said. I don’t think the scientists have much say in what they actually show, at least not if the makers have an interest in doing it differently.

I don’t think they are really interested in the palaeontology behind what they are portraying. At least, this applies to those pseudo-scientific ones, like jurassic fight club and clash of the dinosaurs. So I don’t really think they read scientific papers.

There are likely better ones tough. Planet Dinosaur for example was relatively sound as far as the science was concerned, and others (Dinosaur Planet, Dinosaur revolution) may have humanized the animals’ behaviour too much, but they were not as intend on spreading false facts.
But these documentaries all remain works of entertainment and fiction rather than education.
Edited by theropod, May 2 2014, 04:17 AM.
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Jinfengopteryx
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theropod
May 2 2014, 04:11 AM
Well, they hire scientists to make statements that they then edit into what they would like them to have said.
That's what I think they do with some statements in papers, by making them more sensational than they are. After all, documentaries are a medium to spread new scientific works (OK, maybe not new, as almost all documentaries seem to use no papers from this century).
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retic
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TheMechaBaryonyx789
 
Spinosaurus' bite could inflict damage to a sizeable opponent with ease. You are underestimating these jaws:
with ease?
TheMechaBaryonyx789
 
Laterally Spinosaurus jaws look pretty devastating. The only unimpressive feature about Spinosaurus' jaws is that they weren't very wide, but this doesn't stop its bite from being powerful.
When size-corrected, the B. walkeri resistances to dorsoventral bending remain higher than all other species, but the Spinosaurus falls between the alligator and the gharial

The size-corrected values show that an alligator of the same skull length as a spinosaur has a greater Iy values and therefore a greater resistance to mediolateral bending. Spinosaurus values are lower than those for all crocodilians, whilst the B. walkeri resistance to bending falls between the alligator and the gharial


http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3665537/
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theropod
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The problem was that the part of the snout they compared corresponds to just the premaxillary diastema in the Spinosaurus, which essentially means they only tested what must be by far the weakest spot in its snout.
Posted Image
Posted Image

further back and it would have been far deeper and wider.

In addition, the specimen they used seems to be a subadult, and is far more gracile than MSNM V 4047.
Edited by theropod, May 2 2014, 07:15 AM.
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Vobby
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May 2 2014, 07:13 AM


further back and it would have been far deeper and wider.

In addition, the specimen they used seems to be a subadult, and is far more gracile than MSNM V 4047.
Posted Image

Posted Image

Posted Image


If you bend a thing, it will break in its weakest spot. One weak spot is enough to make a thing break.

The figure 3 of the paper retic posted is MSNM V4047.

Which is not Spinosaurus aegyptiacus.



(I'm missing this thread so much, it gave me all kinds of emotions, but I'll try to really keep my word this time, sorry, bye)
Edited by Vobby, May 2 2014, 08:14 AM.
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theropod
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No, the Cuff & Rayfield did not use MSNM v4047, they used NHMUK 16665. It is just as much of a S. aegyptiacus as the former specimen tough.

If you bend the whole structure it will fail at the weakest spot. But has it occurred to you that an animal does not always bite with the tip of its jaws? If a hyaena crushes bones, does it do that with its incisors? And why is it that theropod premaxillary teeth always look so different from maxillary ones? And why do bite force studies usually estimate values for the anterior and posterior ends of the toothrow?

The gracile, hook-like shape of Spinosaurid premaxillae indicates they had a specialized purpose that did not require great resistance. The largest teeth on the other hand are apparently posterior to it, in a region that is far thicker. Unlike gharial snouts, that of Spinosaurus has a considerable degree of posterior expansion.

That’s what it can be expected to bite with it it excerts large forces–unfortunately that part of the snout wasn’t compared in the study in question.
Thus, it is basically a study on premaxillary bending resistance in crocodylians and spinosaurs, which is of limited relevance.
Edited by theropod, May 2 2014, 06:48 PM.
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Vobby
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theropod
May 2 2014, 06:45 PM
No, the Cuff & Rayfield did not use MSNM v4047, they used NHMUK 16665. It is just as much of a S. aegyptiacus as the former specimen tough.

If you bend the whole structure it will fail at the weakest spot. But has it occurred to you that an animal does not always bite with the tip of its jaws? If a hyaena crushes bones, does it do that with its incisors? And why is it that theropod premaxillary teeth always look so different from maxillary ones? And why do bite force studies usually estimate values for the anterior and posterior ends of the toothrow?

The gracile, hook-like shape of Spinosaurid premaxillae indicates they had a specialized purpose that did not require great resistance. The largest teeth on the other hand are apparently posterior to it, in a region that is far thicker. Unlike gharial snouts, that of Spinosaurus has a considerable degree of posterior expansion.

That’s what it can be expected to bite with it it excerts large forces–unfortunately that part of the snout wasn’t compared in the study in question.
Thus, it is basically a study on premaxillary bending resistance in crocodylians and spinosaurs, which is of limited relevance.
I missed you so much! :wub:

Didn't know they used another specimen, thanks for the correction, but do you really see any significative difference with MSNM V4047? "That rostrum is barely as wide as a human head", would it be a big threat for T. rex, which was the bigger animal between the two?
Also, your comparison with hyenas is poor: they do use canines and incisors to wound and manipulate both prey, conspecifics and the other predators they compete with. They have the cranial robustness to do so, like T. rex, unlike the spinosaurine which had that rostrum. To crush bones, hyenas have to position them with precision in their mouth, and apply several bites. Both Spinosaurus and MSNM V4047 wouldn't have the time or even the brainpower to position their bite with all this attention. I also question their... physical chances to do so: T. rex has the widest skull, neck and torso between the two (three) animals, the spinosaurines would have a harder time biting stuff whit the full force (still 3 times weaker BTW) of their maxillary teeth. T. rex has both the better brain to position its bite, the wider skull to bite a bigger area and to rip a bigger volume, the more damaging teeth and the ridicoulusly higher bone-pulverizing biteforce, in case the rest wasn't enough.
I know everybody know all of this, but all those pages repeting how Spinosaurus-which-is-not-Spinosaurus had a oh-so-wonderfull bite risked to put things out of their perspective.

I have a request: theropod, since you are good at drawing, would you be so gentle to draw how do you figure Spinosaurus using its arms in this fight? I agree that arms may play a role, but I have difficult in actually figuring how.
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theropod
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There is a significant robusticity difference between the two, compare the image you posted and that of the rostrum in the study.
"That rostrum is barely as wide as a human head" doesn’t mean much, it is taken out of context.

As I showed earlier (which strangle nobody reacted to), and unlike a human head, it is composed of almost solid bone. Crocodiles too have fairly thin snouts (and far less compact ones!), which obviously does not keep them from being strong enough to handle even large, struggling prey.

My analogy with hyaenas is not vital to my point–which is self-evident. But I don’t know how exactly the robusticity of its jaw apparatus invalidates it. If anything, it strenghtens the suggestion for Spinosaurus.

People are not repeating how Spinosaurus’ bite was "oh-so-wonderfull". I’d rather say they are trying, and correctly so, to clarify that Spinosaurus’ bite is not that of a heron.
Nobody here will raise even the slightest doubt about T. rex having a more potent bite if asked, I’m fairly certain of that. But T. rex’ "oh-so-wonderfull" bite is not everything, and it does not mean the bite of an animal not primarily adapted for large terrestrial prey cannot still be potent.

And regarding the non-referral of the rostral remains to Spinosaurus, why are you so certain? Can you name me one other Mid-Cretaceous, African Spinosaurine that is differentiated from others based on diagnostic remains?

I’m not really good at that kind of drawing, but I’ll try. Something between an eagle and a monitor lizard…
Edited by theropod, May 2 2014, 08:21 PM.
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