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Giganotosaurus carolinii v Tyrannosaurus rex
Topic Started: Jan 31 2012, 05:48 PM (110,339 Views)
Taipan
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Giganotosaurus carolinii
Giganotosaurus ("giant southern lizard"), was a carcharodontosaurid dinosaur that lived 93 to 89 million years ago during the Turonian stage of the Late Cretaceous period. It is one of the longest known terrestrial carnivores, bigger than Tyrannosaurus, but in length and weight, smaller than Spinosaurus. Although longer than T. rex, G. carolinii was lighter and had a much smaller braincase that was the size and shape of a banana. A well-developed olfactory region means it probably had a good sense of smell. Titanosaur fossils have been recovered near the remains of Giganotosaurus, leading to speculation that these carnivores may have preyed on the giant herbivores. Fossils of related carcharodontosaurid fossils grouped closely together may indicate pack hunting, a behavior that could possibly extend to Giganotosaurus itself. he holotype specimen's (MUCPv-Ch1) skeleton was about 70% complete and included parts of the skull, a lower jaw, pelvis, hindlimbs and most of the backbone. The premaxillae, jugals, quadratojugals, the back of the lower jaws and the forelimbs are missing. Various estimates find that it measured somewhere between 12.2 and 13 m (40 and 43 ft) in length, and between 6.5 and 13.3 tons in weight. A second, more fragmentary, specimen (MUCPv-95) has also been identified, found in 1987 by Jorge Calvo. It is only known from the front part of the left dentary which is 8% larger than the equivalent bone from the holotype. This largest Giganotosaurus specimen is estimated to represent an individual with a skull length of 195 cm (6.40 ft), compared to the holotype's estimated at 1.80 m (5.9 ft) skull, making it likely that Giganotosaurus had the largest skull of any known theropod. Giganotosaurus surpassed Tyrannosaurus in mass by at least half a ton (the upper size estimate for T. rex is 9.1 t). Additionally several single teeth, discovered from 1987 onwards, have been referred to the species.

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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. 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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Prehistoric Cat
Jan 31 2012, 04:53 PM
Giganotosaurus VS Tyrannosaurus
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theropod
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The point about binocular vision is not the forward-facing field of vision, it is the depth perception in this field.

I don’t know, but I assume some people take their illusions on this matter from portrayals in old documentaries, which are plain incorrect. Giganotosaurus would not have a blurry or no vision at all in front of it.
Both eyes could see forwards perfectly well, and there would be absolutely no need to "shake its head from side to side to do that" (Do you see extant animals with poor binocular vision do that? No, rather in those with good binocular vision actually!). Vision in Giganotosaurus would be largely independent of head movements (which imo makes sense and is actually advantageous).

The only issue is that the overlap (hence "binocular vision") of the two separate fields of vision was smaller, ~20% judging from other carnosaurs (that is a value comparable to pidgeons and many other extant reptiles). Imo people are overrating and overgeneralising how important the resulting advantage for depth perception is.

If I close one eye, that does not make a noticeable difference as to whether I can hit someone in front of me. Animals simply rely on their vision to different degrees, that does not preclude predatory sucess in animals that lack a large binocular field (even predators with generally poor vision can still launch very quick, precise strikes). It is an adaption with noticeable benefits for specific lifestyles and over geological timescales. Much less so in a confrontational setting.

Having a much wider field of vision→ can be just as much of an advantage.
Edited by theropod, May 6 2014, 05:35 AM.
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Vobby
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I completely agree with this^, we could perfectly ignore binocular vision, it's a non factor, it is clear that both these animals had senses which allowed them to hunt and fight.
There is another thing I would like to read other members opinions about: the importance of brain size. T. rex has a bigger braincase so, I guess, the more likely consequence is that it had a bigger brain, so more brainpower. Now, I'm not making hypothesis about the ability of T. rex to fight using some kind of complex tactic: to me, these two theropods would just go and bite each other face and neck, charging one against the other. So strategy would be another non factor.
But, brainpower is not only about intelligence, it's also about coordination and precision. Have you ever read some threads in the interspecific conflicts involving the Tasmanian devil? Everyone recognize its strenght, but then someone posts this video:

https://www.youtube.com/watch?v=iyvPjn2m240

I'm not sure, maybe Felinepowah, explained my sensation too: "it's like their brain are struggling to tell the body what to do". They appear, compared to the placental carnivores we are used to, much less coordinated, slower both in moving and in reacting.
Something similar was discussed in this thread:

http://carnivoraforum.com/topic/9792828/1/

the match between african lion vs amphicyon major. One of the point Ursus made, if I got it correctly, is that one of the reasons placental carnivores have bigger brain than marsupials (and some amphcyonids, it seems) is that they make up the lack of strenght of their bites (much higher for guys like the tasmanian devil and the quoll) with enanced dexterity, precision, balance and overall complexity of the hunting (...fighting) method. Even if the strategy is similar (ambush, for example), the predator with better brain would probably show better athleticism, better ability in delivering a killing bite, better skills in evading the weapons the opponent may have.
So, in short, I wonder if something similar may happen in a fight with these two theropods. Now, I don't really care who wins between this two ("the bigger individual wins, at parity both die in an orrible bloodshed" seems a good rule to me for these matchese with giant theropods, with just some exceptions), I just think it may be a good occasion to discuss the importance of brain size in matches involving theropods.
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theropod
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Firstly, brain size becomes less meaningful the more distantly related two animals are, and these two obviously are quite distantly related.

Secondly, what gives Tyrannosaurus its relatively bigger brain is mainly its enlarged cerebrum, which is not so relevant for coordination afaik. That would rather be the domain of the cerebellum, and the athleticism is a matter of the inner ear.

http://www-personal.umich.edu/~wilsonja/JAW/Publications_files/Larsson%26al2000.pdf

The large cerebrum I would rather attribute to other aspects of its lifestyle, perhaps gregarious behaviour etc.

Thirdly, neither Marsupials nor reptiles seem uncoordinated beyond what other aspects of their physiology (being ectoterms or just generally neither built for, nor in need of athleticism) dictate.
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Vobby
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theropod
Mar 28 2014, 10:32 PM
Firstly, brain size becomes less meaningful the more distantly related two animals are, and these two obviously are quite distantly related.

Secondly, what gives Tyrannosaurus its relatively bigger brain is mainly its enlarged cerebrum, which is not so relevant for coordination afaik. That would rather be the domain of the cerebellum, and the athleticism is a matter of the inner ear.

http://www-personal.umich.edu/~wilsonja/JAW/Publications_files/Larsson%26al2000.pdf

The large cerebrum I would rather attribute to other aspects of its lifestyle, perhaps gregarious behaviour etc.

Thirdly, neither Marsupials nor reptiles seem uncoordinated beyond what other aspects of their physiology (being ectoterms or just generally neither built for, nor in need of athleticism) dictate.
I hoped in your aswer! I remember you having wrote about this matter, but I didn't manage to find the post again.

About the first point, I kinda agree, but would you like to explain a little more? The two brains are identical, except for size and enlarged cerebrum.

About the second point, wikipedia states this about the cerebrum:

"Movement[edit]
The cerebrum directs the conscious or volitional motor functions of the body. These functions originate within the primary motor cortex and other frontal lobe motor areas where actions are planned. Upper motor neurons in the primary motor cortex send their axons to the brainstem and spinal cord to synapse on the lower motor neurons, which innervate the muscles. Damage to motor areas of cortex can lead to certain types of motor neuron disease. This kind of damage results in loss of muscular power and precision rather than total paralysis.
It functions as the center of sensory perception, memory, thoughts and judgement; the cerebrum also functions as the center of voluntary motor activity."
It seems related to coordination, balance and dexterity to me!

Besides this, quoting you source, the brain volume is around 100% bigger in T.rex than in Giganotosaurus, while the percentage occupied by the cerebrum is 32% in T. rex and 26% in Giganotosaurus. Unless I'm getting something very wrong, the whole T.rex's brain is considerably bigger.

Marsupials aren't really related with this stuff, it was just an example, but most members seem to agree in considering carnivore ones much less bright and dexterous than placentals. Anyway, if you look into the thread I linked you'll see some interesting considerations made by Ursus and Coherentsheaf (quoted) about the relevance of brain size.
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theropod
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T. rex total endocast volume is 343ml (Larsson et al 2000), that of Giganotosaurus is 275ml (Carabajal and Canale 2010). Of the latter, approximately 50ml are cerebrum, of the former, approximately 112ml.

So when subtracting the cerebral volume, attriobutable to typical derived-coelurosaur-style forebrain enlargement, what remains is 231ml in T. rex and 225ml in Giganotosaurus carolinii. Not a big difference, is it?

No two brains are identical. The morphology of T. rex’ brain is certainly not the same as that of a carnosaur or ceratosaur.

The voluntary motor functions, that’s the point. We know for sure that all these animals are fully capable of moving voluntarily, and of course many of their movements during a fight would be voluntary, but we are not talking about complex tactics, we are talking about fighting behaviour largely powered by instinct. Fighting is not really closely linked to "intelligence".

note the following quote on the importance of the cerebellum:
Quote:
 
The cerebellum does not initiate movement, but it contributes to coordination, precision, and accurate timing. It receives input from sensory systems of the spinal cord and from other parts of the brain, and integrates these inputs to fine tune motor activity.[2] Cerebellar damage does not cause paralysis, but instead produces disorders in fine movement, equilibrium, posture, and motor learning.[2]

http://en.wikipedia.org/wiki/Cerebellum

I presume these are the important points in a fighting scenario. I am of course familiar with the impact brain size has on ecological sucess in related species.
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Vobby
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theropod
Mar 29 2014, 01:15 AM
T. rex total endocast volume is 343ml (Larsson et al 2000), that of Giganotosaurus is 275ml (Carabajal and Canale 2010). Of the latter, approximately 50ml are cerebrum, of the former, approximately 112ml.

So when subtracting the cerebral volume, attriobutable to typical derived-coelurosaur-style forebrain enlargement, what remains is 231ml in T. rex and 225ml in Giganotosaurus carolinii. Not a big difference, is it?

No two brains are identical. The morphology of T. rex’ brain is certainly not the same as that of a carnosaur or ceratosaur.

The voluntary motor functions, that’s the point. We know for sure that all these animals are fully capable of moving voluntarily, and of course many of their movements during a fight would be voluntary, but we are not talking about complex tactics, we are talking about fighting behaviour largely powered by instinct. Fighting is not really closely linked to "intelligence".

note the following quote on the importance of the cerebellum:
Quote:
 
The cerebellum does not initiate movement, but it contributes to coordination, precision, and accurate timing. It receives input from sensory systems of the spinal cord and from other parts of the brain, and integrates these inputs to fine tune motor activity.[2] Cerebellar damage does not cause paralysis, but instead produces disorders in fine movement, equilibrium, posture, and motor learning.[2]

http://en.wikipedia.org/wiki/Cerebellum

I presume these are the important points in a fighting scenario. I am of course familiar with the impact brain size has on ecological sucess in related species.
Uhm, then I'm really not getting why that paper states that there is a difference of 100%...

About istinct and intelligence: I completely agree about the fact that things like "tacticts" are completely irrelevant in this scenario, both of them were probably incapable of thinking about any strategy more complicated than an ambush, which doesn't matter here. I also couldn't care less, right now, about who would win about this two (lol I'm joking, T. rex wins, but this is absolutely besides the point, I swear!).
What I find interesting, and that would be useful, is to try and establish the point in which istinct starts to be a "tactic". Actually, I think it's a good idea to talk about method: for example, is the neck bite delivered by pantherines a "killing strategy"? Method sounds better to me. It is "powered by istinct"? I guess it is, but learning processes matters, like playing with brothers while cubs or watching at mothers' hunt. Captive animals, in fact, may usually be inept at hunting, no? Experience matters, and experience in this case is the interiorization of a more or less complex movement, which becomes authomatic and, we would say, istinctual. Now, are "experienced movements" related to cerebrum or cerebellum? Cerebrum I guess, but I'm moving in a field in which I'm very ignorant. Maybe i should make a proper thread about this, it may start to be off topic...
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theropod
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Firstly, the paper was not talking about Giganotosaurus. Secondly, the 100% difference refers to the volume of the cerebrum, not the whole brain. The latter is just about half that.
Edited by theropod, May 6 2014, 05:37 AM.
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theropod
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I think you are right there. Attacking methods are a matter of the cerebrum, whether they are instinct or learned behaviour (I think a bit of both).

But both of these animals were obviously fully capable of delivering fatal killing bites. The difference merely lies in how they did it; T. rex simply needs more precision to do that sucessfully, this precision is not an additional advantage. For reference, compare the hunting methods of a komodo dragon or shark and a pantherine–the former two manage perfectly well with much less "brainpower" and precision.
One of the reason why the latter has a large brain is certainly that it relies more on precision, which in turn derives from the fact that due to evolutionary and ecological reasons it is precluded from developing certain types of jaw and tooth designs (ziphodonty and diphyodonty don’t work well together). The matter is similar to the giraffe and its strange laryngeal nerve…
Edited by theropod, May 6 2014, 05:39 AM.
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Vobby
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I agree. On the other hand, precision and dexterity may prove usefull in avoiding getting bitten too, or in better controlling the opponent's weapons, or attacking with better timing, still speaking in general. I think I'll do a proper thread, if I got less lazy.
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theropod
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We see reptiles and sharks (think of striking snakes or crocodiles, lunging komodo dragons or impact-feeding great whites) with tiny brains attacking with a speed, dexterity and efficiency that no carnivoran or primate could manage better (hinting at two of my previous points). Again, I think (I might be wrong tough) that this is largely in the cerebellum’s domain of responsibility, along with the general coordination of movements.
Evasive maneuvers are not that much about precision imo, rather about flexibility, range and speed of movement (Giganotosaurus is likely superior in these points). One does not plan or think about dodging an attack, it’s a response based on reflexes and instinct.

The Cerebrum affects the way an animal "thinks", it will matter for how it decides which method of attack to use (or when not to attack), but I do not think that will matter here given that the vast majority of animals does not use learned martial arts or strategy.
Edited by theropod, May 6 2014, 05:40 AM.
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Megalodon
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T rex wins. Easy. Gigantosaurus had horrible eye sight and was clumsy. T rex had some of the best eye sight of all dinos and was very VERY clever. T rex was also fast (not the fastest but fast) so he could get bites in faster than gigantosaurus. But gigantosaurus hunted huge prey and also has a size advantage over t rex. but still t rex wins 60% of the time :P
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spinosaurus rex
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are you serious? please say your joking
if not, look below
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Edited by spinosaurus rex, Apr 18 2014, 11:48 AM.
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theropod
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He must have been joking.
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ArachnidKid
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so megaladon says her thoughts for rexy they must be joking, but anything aginst rexy is applauded...that is why i stopped replying to the tyrannosaur vs spin. thread, fanboys rip you a new one.I think it's 50/50 here since both have weapons to take the other out at the first chance of a slip up
Edited by ArachnidKid, May 6 2014, 01:07 AM.
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Jinfengopteryx
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You don't understand, megalodon is not ridiculed for favoring Tyrannosaurus (I also made points in favor of Tyrannosaurus in some threads). It are the arguments who are criticized, not the position. Be honest, theropod made a post which is right above megalodon's which completely refutes it. He didn't assess eyesight, but it is the same principle as with reflexes/dexterity and the analogies are valid. Intelligence also was discussed often enough.
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