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Spinosaurus aegyptiacus v Tyrannosaurus rex
Topic Started: Jan 7 2012, 02:16 AM (459,134 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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blaze
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I think that trying to make it much bigger than T. rex based on the current fossil evidence is doing it a disservice, by either making it out to have a narrow, long-snouted head that is ridiculously small compared with the rest of the body or by making it out to be arguably the most unathletic giant theropod there is, combining its "diminutive" vertebrae with weights over 10 tonnes.

Some people are so enthusiastic with increasing its "stats" that are forgetting the biomechanical implications of doing so.
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theropod
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Is there any way you can make Spinosaurus have anything but a narrow, long-snouted skull? With a snout almost a metre long and about 20cm wide that seems undisputable.

There are many points to consider besides athleticism (although I think nobody doubts Spinosaurus is a less athletic animal than T. rex, especially given that it’s bigger). There’s fatigue (spending half your time in water=less of it), there are different modes of loading due to differences in the internal and external built of the vertebrae, there are different savety factors due to differences in what the animal needed to do on a regular basis.

Has anyone ever tried to quantify what effect having pro- or opisthocoelous vertebrae as opposed to amphiplatyan or amphicoelous ones has for example? How much bigger do the latter have to be in order to resist dislocation to the same degree?
That could very well be the main factor here, along with bending strenght of the vertebra itself (complicated by that of the spinous process of course), not resistance to axial compression (which bone is both very strong in and which external dimensions don’t matter much for).
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blaze
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"narrow, long-snouted head that is ridiculously small compared with the rest of the body"

That goes together, I'm not disputing that you can't reconstruct the head as anything but narrow and long snouted but what I meant is how big that head ended up proportional to the body, the larger "reconstructions" gave a head that was long and narrow on top of being relatively "tiny".

That's another one regarding my athleticism comment, if based on current evidence is larger it'll be less athletic even if its vertebrae was similar in size to that of T. rex but is not, is much smaller making it comparatively even more sluggish. Are we sure Spinosaurus spend its time inside the water? isn't its feeding model compared to that of a stork rather than a crocodile?

I don't think such analysis has been done (that of vertebral shape).
Edited by blaze, Sep 8 2014, 07:19 AM.
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theropod
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How tiny it is compared to the rest of the body doesn’t change its absolute size, or that of the fish it likely hunted. Also, nothing changes the lenght of those vertebrae.

It is possible it had a proportionately larger head than Baryonyx or Suchomimus. It’s also possible it didn’t, allometric enlargement of the jaws may not be present in an animal that specialized in smaller prey.
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blaze
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That's what I mean, no matter if you make it 9, 10, 11 tonnes or more it'll still have the same long narrow jaws that aren't much more wider than 20cm at the tip and throughout their length.

And nothing changes how shallow and narrow those vertebrae are too.
Edited by blaze, Sep 8 2014, 07:18 AM.
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theropod
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Yes, my point was that no matter how heavy you might "make" it, the lenght of its body and therefore the proportions between its head and body are somewhat constrained by the lenght of its vertebrae. The relevance the diameter of these vertebrae has has yet to be clarified.

I think I’ve already argued elsewhere that we can realistically get a Spinosaurus holotype 70-84% the body mass of Sue (i.e., basically T. rex-sized) using Hartman’s reconstruction of its proportions and Cau’s estimate for the width of the body, and I still retain that I think MNSM V4047 is about 37% larger overall-as comical as some people might find my and Dal Sasso et al.’s restoration of the lower jaw, I incorporated all the material as best I could, and I think so did they, and independently the results were fairly similar.
Now I admit that my mass estimate needs a redux due to issues with the silhouette I traced, but I find the head-body proportions on Hartman’s Spinosaurus fairly believable (though maybe that’s simply because it is the skeletal we all grew to think of as the default), don’t you?
The only thing I disagree with is the relative scaling of the dentary and rostrum that apparently yielded only little over 11% difference for him.
Edited by theropod, Sep 8 2014, 07:28 AM.
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blaze
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I also found his (Cau's) reconstruction to look weird but not so much after the scaling I did with Baryonyx skull elements, the dentary ends up looking similar.

That paper can't come soon enough.
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theropod
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Yeah, that seems to be a far too common condition in palaeobiology.

"Just wait ’till that paper comes out, it should be due any day now!
Months later…
I just read an announcement that that taxon is going to be published soon!"
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Spartan
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theropod
Sep 8 2014, 07:26 AM
I think I’ve already argued elsewhere that we can realistically get a Spinosaurus holotype 70-84% the body mass of Sue (i.e., basically T. rex-sized) using Hartman’s reconstruction of its proportions and Cau’s estimate for the width of the body, and I still retain that I think MNSM V4047 is about 37% larger overall
37% larger than Sue or than the holotype?
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theropod
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That of the holotype.
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theropod
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Sorry, I meant 36. I always mess that up because I used to use different figures before I finished my updated reconstruction.
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Verdugo
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Well, it seems I did 't misunderstand it.
As I already wrote, ichthyosaurs and plesiosars are simply not a relevant analogy. These are, again, animals with vastly different relationships and lifestyle. And yet, as I wrote earlier, at least ichthyosaurs do seem to have had proportionately smaller vertebrae. Their vertebral proportions (which are simply a result of having a different number of vertebrae along with a very different body shape, not with aquatic habits) were not the point, their size was.
It would have to be demonstrated that semi-aquatic habits have no influence on relative vertebral diameter. And if fully aquatic animals like Ichthyosaurs (or sharks, or whales…) were really a relevant analogy, then that already seems to be falsified, as these do appear to have proportionately smaller centra than Tyrannosaurus.

Given you accept that T. rex was cursorial and Spinosaurus was semi-aquatic, there can really be no doubt that this represents a relevant difference, among others completely opposed to the notion that if you know their relative vertebral diameters, you know their relative body masses.

No you still misunderstood me ! I'm not here to talk/discuss about f****** Ichthyosaur, Plesiosaur or Gallimimus.
Here's the link original in Italian, use Google translator or whatever translator that help you understand. I think what Cau pointed out here are pretty clear that i'm not expected to have any discussion about this.
http://theropoda.blogspot.com/2013/12/risposta-ai-lettori-vertebre-di-t-rex.html

Pneumatization has nothing to do here, you know pneumatization has no relation to bone strength , don't you ??

I know you're not satisfied so here are the BONUS:



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Posterior dorsal vertebrae of various theropodi views in lateral right (left) and posterior (right). From top left: Spinosaurus , Tyrannosaurus , Ichthyovenator , Allosaurus , Baryonyx and Carnotaurus .
Cau
 
Inspired by the previous post I made ​​the image above, to compare the posterior dorsal vertebrae of some great theropodi. Note that the dorsal centers all have similar proportions (veneers ellipticals, constriction median longitudinal), demonstrating that these bones retain the same general shape and function and are not "special" for some clade than others. That is, the shape of the dorsal centers in theropodi is little affected by the phylogenetic-Position, and then you can compare the vertebrae of allosauroidi, ceratosauri, megalosauroidi and celurosauri, since all are bound to the same biomechanical function, unrelated to the phylogeny: support the body weight.
In fact, this general constancy of form allows you to do some calculations, as approximate. The weight of discharge along a surface perpendicular to the force of gravity, therefore, the weight that each vertebra can bear is approximately proportional to its transverse surface. Given the general isometry centers vertebral (all are sub-cylindrical with a central constriction that makes them look like - in section - in hourglasses) can approximate the surface discharge of the weight on the vertebra to a form proportional by a constant k to the ratio ( length * width).
Then using this ratio as a rough estimate of the weight force bearable by vertebra, and since all theropodi mentioned herein are bipedal posture and a number of the dorsal vertebrae approximately constant (13-14 vertebrae) can be estimated using the cross-sectional area of ​​the vertebral centers as an indirect measure of the weight force unloaded.
According to the calculations, it appears that Tyrannosaurus has the vertebral surface (and hence the mass) greater. And what was already evident by observing the vertebrae, given that is clearly wider and robust. The other taxa have transverse surfaces (and thus, approximately, the weight forces) below, according to proportional values, which express as a percentage of a Tyrannosaurus :

Spinosaurus (holotype) 46%
Ichthyovenator 37%
Allosaurus 28%
Baryonyx 32%
Carnotaurus 26%

The hypothetical Spinosaurus with vertebrae "expanded" by 120% compared all'olotipo, it is with a mass equal to 55% of Tyrannosaurus .

[So if - for example - Tyrannosaurus was a mass of 8 tons, the other taxa have masses of, respectively, 3.7t, 3t, 2.2T, 2.6t, and 2t. Spinosaurus "120% Version" is 4.4 tons]




Cau
 
Anyway, my guess is a scientifically testable prediction: if Tyrannosaurus is actually more massive vertebrae as compared to Spinosaurus , then his rib cage was broad, and his chest much more voluminous, and therefore, its shores dorsal described a curve larger than in the Spinosaurus .
The size of the rib cage in disjointed and fragmentary specimens (such as Spinosaurus ) are difficult to determine. However, fortunately for us, the holotype described by Stromer (1915) includes a partial intermediate dorsal coast. Stromer provides us with the measurements of the specimen: the coast is at least 83 cm long, and has a capital of at least 10.5 cm. Although the terminal part of the coast is missing, we can estimate the total width of the coast based on its curvature.
For abozzare the total size of the coast, we use its curvature, tilting the capital of 30 ° to simulate its articulation with the dorsal vertebra, and inscribe an ellipse that follows the trend of curvature of the coast. The ellipse that is obtained is a good estimate of the amplitude of the lateral half of the chest. To make happy the supporters of the " Spinosaurus great 120% of the holotype "magnify this result by 120% for a hypothetical chest" maximum ".
This is the result.

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Cau
 
Now, repeat the same procedure using a dorsal mid coast of Tyrannosaurus , or from a position homologous to that of the rib cage from which the coast of Spinosaurus used before. The costs in question is 147 cm long and 32 cm long has the capital. We tilt the capital of 30 ° to have the same articulation with the vertebrae attributed to Spinosaurus . Moreover, since the costs of Spinosaurus was devoid of the terminal, to estimate the equivalent ellipse in Tyrannosaurus identify the point along the coast of Tyrannosaurus which corresponds to the final part preserved in the coast of Spinosaurus , and exclude the mail from our past that point speech. At that point we inscribe the ellipse exactly as done for Spinosaurus .
This is the result.

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Cau
 
Once again, exactly as in the case of the cervical vertebrae, the rostrum, dental and dorsal vertebrae, including the rib cage of Tyrannosaurus is much broader than that of Spinosaurus , even for the hypothetical example "120%". And also in this case, the result is based directly on the fossils, using a repeatable method and directly comparing homologous parts between the two animals.
The larger volume of the rib cage is clearly consistent with the larger size of the vertebrae, so it is - once again - very likely that Tyrannosaurus had a body mass much greater than Spinosaurus . As you can see, the evaluation of the various factors leading to the same result: it is not "extrapolate" from a single datum, but rather to analyze the different factors, and then integrate them into a common interpretation.

Cau
 
Nell'olotipo of Ichthyovenator , is preserved a nearly complete dorsal coast, adjacent to a posterior dorsal vertebra (probably the twelfth ). Since the neural arch of the vertebra that is very similar to that of one of the backbones of the holotype of Spinosaurus , you can use this coast backbone, articulated to the corresponding vertebra of Ichthyovenator , to estimate the amplitude of the rib cage at the level the twelfth dorsal Spinosaurus .
then using the same dorsal vertebrae and ribs corresponding Tyrannosaurus , I compared the width of the rib cage at the back of the chest, near the pelvis. As always, to meet the needs of all, I've also included a hypothetical version of Spinosaurus "expanded by 120%" compared all'olotipo.

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Cau
 
Although for the layman large theropodi may appear all quite similar, and differ only for the presence of or ornamentation for the proportions of the skull, there is a wide variability of morphologies. These differences usually involve differences in ecology, which, translated in a nutshell, means "different lifestyles".
Although deduct the ecology of an extinct dinosaur is difficult in the absence of internal evidence (such as food remains, fossil associations with other organisms or strong environmental correlations), you may exclude certain "lifestyles" if the animal in question "lacks the physical requirements" deemed appropriate for this "style".
A parameter is easy to determine and quite informative about some aspects of the ecology is given by the strength of the bones. Animals with robust body types tend to have different lifestyles from animals with slender body types. In addition, body size impose limits biomechanical which, added to the body proportions, further restrict the range of "benefits" that animal can perform. We can use as a robustness parameter of a report, which I call R, equal to the width of the bone mediolateral (measured in the middle of the bone), divided by its length, expressed as a percentage. If, for example, a bone has amplitude equal to half the length, that bone has R = 50.
The spinosauridi in particular skeletons show relatively puny compared to the other big theropodi. They have elongated and tapered beaks (R specimen Milan Spinosaurus = 18, while in Allosaurus , R = 35, and in Tyrannosaurus R = 46), dental very gracile (R holotype of Spinosaurus = 6, in Majungasaurus, R = 10), elongated in both presacral vertebral centers (R in the backbones Spinosaurus = 25, in the backbones Neovenator R = 46) that in the caudal (R caudal in front of Baryonyx = 20, in front of caudal Allosaurus = 43, in the caudal front of Ceratosaurus = 61), neural spines very gracile (R Spinosaurus = 6, Tyrannosaurus R = 27), and the humerus that, despite the presence of large muscle insertions, is however relatively frail and below the range of other taxa ( R of Allosaurus = 13, R Baryonyx = 15, R Tyrannosaurus = 19, R Acrocanthosaurus = 19). All these data suggest that the eco-ethology of spinosauridi was different from that of other theropodi, and that, in particular, behave stress musculoskeletal minors, then that did not require a particular skeletal robustness. This is not surprising if we consider that the morphology of the skull and teeth, the remains of the meal, the isotopic analyzes and sedimentological agree to the ecology of piscivorous purely for these animals, and reduced (if not absent) tendency to predation and macrophage ipercarnivora. All these different points of view, therefore, we suggest that spinosauridi were used to avoid interacting aggressively towards other animals of comparable size to them. Added to the large size of these animals, I think the Spinosaurus should be regarded as lovers of the elegant and peaceful bodies of water, like that of large water birds avoided as much as possible conflict and confrontation with other dinosaurs, preferring fishing for small to medium sized prey.


If those are not enough to convince you then i would consider you being ignorant and stop debating here (because you've given me nothing exciting). All you have to defend for your point (Spino being more massive than T-rex) are Paul's statement in a very generic way, lifestyle differences and pneumatization arguments (lifestyle differences and pneumatization arguments have been demonstrated to be invalid by Cau). Seriously, back yourself up with proofs (including publication papers, books, research/quotes from scientists), your pure opinions won't convince anybody
Edited by Verdugo, Sep 9 2014, 12:34 AM.
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Spartan
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theropod
Sep 8 2014, 11:56 PM
That would make it not significantly heavier than Sue. In this case I would favour the T-Rex.
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theropod
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Spartan
Sep 9 2014, 02:32 AM
theropod
Sep 8 2014, 11:56 PM
That would make it not significantly heavier than Sue. In this case I would favour the T-Rex.
Err what? It definitely would!
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The Reptile
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Sep 8 2014, 02:06 AM
Sorry if this sounds a bit stupid, but I had a discussion with one of the few decent posters on topix who assumed that Spinosaurus could, as a fish-catcher, have an edge in reflexes. What do you think? I believe this is highly speculative because Spinosaurus' fishes were probably not that fast and a technique that consisted of restraining and killing larger ones would be more likely than killing swift ones with a quick bite.

P.S. Three words that mean fast in one sentence, nice!
It was undoubtedly capable of striking its jaws down and inward on fish, but that is where it needs to be capable of quickness. Locomotory quickness is just not as necessary for it as it is for other theropods because it would most likely not be chasing down fast-moving prey. And still, spinosaurus would be striking down with its jaws anyway; it is not going to be killing things by chasing them down. Whether or not its preferred prey type is powerful or not, it was designed for quick head-striking and restraining.
Edited by The Reptile, Sep 11 2014, 07:34 AM.
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