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Spinosaurus aegyptiacus v Tyrannosaurus rex
Topic Started: Jan 7 2012, 02:16 AM (459,164 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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theropod
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Tyrannoceratospinosaurus Rex
Feb 10 2014, 09:37 PM
TheMechaBaryonyx789
Feb 10 2014, 06:58 AM
Tyrannoceratospinosaurus Rex
Feb 10 2014, 04:53 AM
^ T.Rex looks more massive even in side view IMO. But this is the holotype....
Not really, their mid-torsos appear to be around the same size/depth, and Spinosaurus' sail would add more weight.
Maybe you're right. But just asking, is there any way to know how much Spino's sail (or whatever it was) may have weighted? I'd really like to know this

There’s a ton of ways to guesstimate it (one of which I used), but in the end it breaks down to the shape of its cross-section, which we do not know. But I find it highly unlikely it was shaped like a "sail" (the way you always get to see it on TV, or restored for Dimetrodon, a narrow crest protruding from the body outline and remaining uniform in width throughout).

Much more likely, it will be a tapering, roughly triangular structure, with musculature concentrated near the base, ligaments near the apex of the neural spines, and a bit of cushioning of fat and fascia.
A bit like this, resembling the tall backs of chameleons:
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(that’s an Arizonasaurus of course, but it has a similar ridge).

Imagine cutting off the structure at mid-height, cutting that in half in the sagittal plane, and aligning the pieces at the base, that’s how I’d approximate it’s volume with the "regular" body outline.

How much tissue exactly is difficult to say, that’s why I included two approaches. I find something in between the most realistic I think.

Both of them end up more than 70% heavier than the largest Tyrannosaur btw.
Edited by theropod, Feb 11 2014, 12:53 AM.
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Tyrannoceratospinosaurus Rex
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Hatzegopteryx
Feb 10 2014, 09:29 PM
Tyrannoceratospinosaurus Rex
Feb 7 2014, 05:19 AM
theropod
Feb 7 2014, 04:07 AM
So T. rex is "the biggest and strongest theropod" now? And Spinosaurus again a weak fish eater? I thought we were long over this...
No one said that Tyrannosaurus is ''the biggest and strongest theropod''. That's crazy talk lol And no one said Spinosaurus is weak. It just seems that Tyrannosaurus was bulkier than Spinosaurus.
Bulk becomes irrelevant if Spinosaurus turns out to be larger
I don't think Spinosaurus will turn out to be bigger (bigger by bulkiness) In fact i think he's gonna get downsized.


@theropod thanks for answering!
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theropod
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With "turn out bigger" he meant "turn out to have a bigger body mass", not "turn out to be bulkier".
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Hatzegopteryx
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theropod
Feb 10 2014, 09:40 PM
@hatzegopteryx: sure you aren’t forgetting some parantheses or something like that?

It has always worked fine with every calculator for me:
#lenghtB divided by lenghtA (÷)

#Then take the cube of that number (³)

#Then multiply by the known weight for lenghtB (×)

It works both ways, for scaling up and for scaling down.
I am not a genius in maths, but sure I did it correctly apparently and the calculator simply gave me a ridiculous result.
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Hatzegopteryx
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Tyrannoceratospinosaurus Rex
Feb 10 2014, 10:00 PM
I don't think Spinosaurus will turn out to be bigger (bigger by bulkiness) In fact i think he's gonna get downsized.
I don't think it is bulkier either, but I meant body mass (which is actual size instead of length, since that is a two dimensional measurement)
Edited by Hatzegopteryx, Feb 10 2014, 10:07 PM.
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coherentsheaf
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theropod
Feb 10 2014, 08:46 PM
Why? If it’s tail is deeper, it is deeper, and will be more massive unless it is considerably narrower (which it is of course, but I accounted for that). What will be affected by variation in tail lenght is not the bulky part (that holds most of the important musculature), but the thin tip that has barely any mass.

Owing to the built of Spinosaurs, their tails would have been fairly deep.
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Note this depth I’m assuming is to approximate the mass the ridge would add, for different amounts of bulk. That’s why I took a slightly to considerably deeper body outline. The smaller one accounts for a fairly slender structure, the bigger one is for a roughly triangular crest.

or do you mean this?
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its neglegible, just around 400px, a difference of slightly above 1% (and only affecting the conservative measurement)

Scaling the Suchomimus outline to approximately the size of the spinosaurus holotype, there is no marked disparity with regards to the depth of the tail compared to the same thing in the case of the rather fat Spinosaurus tail:

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theropod
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I couldn’t reproduce that. Suchomimus, when scaled after Hartman’s skeletal and to the same standing lenght as the Spinosaurus, has a considerably deeper tail based than sue:
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I’ve superimposed them as for their pubic boots to be at the same point.

If you use snout-ventral lenghts, it gets even more marked.


Posted Image
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Also, Spinosaurus likely had an even fatter tail (at least laterally) since its sacral spines were so tall.
Edited by theropod, Feb 11 2014, 12:43 AM.
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coherentsheaf
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This time I took more care while scaling and indeed I scaled wrong the first time. Still the difference in tail area between Suhomimus and Spinosaurus is greater than the one between Tyrannosaurus and Suchomimus.
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theropod
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I think partly due to the T. rex’ hip being further posterior, so that the most massive part of its tail is too.
It’s all based on Hartman’s restoration, although how much of the neural spines you incorporate is indeed up to debate.

btw what do you think about the scaling matter of the dentary and rostrum?
Edited by theropod, Feb 11 2014, 12:58 AM.
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coherentsheaf
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theropod
Feb 11 2014, 12:57 AM
I think partly due to the T. rex’ hip being further posterior, so that the most massive part of its tail is too.
It’s all based on Hartman’s restoration, although how much of the neural spines you incorporate is indeed up to debate.

btw what do you think about the scaling matter of the dentary and rostrum?
Headdens post seems pretty conclusive that these are different species. Unmodified reconstructions with holotype mandible and the large rostrum look weird, but this could simply be due tothe rostrum being a different species. Your reconstruction with the mandible scaled up seems to result in an implausibly strong mandible, gven that the rostrum would have been subject to similar bending forces. My best guess is that rostrum beongs to an animal somewhat larger than the holotype but probably not as much larger as in the largest scaling you did.
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theropod
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Would the rostrum actually be subject to similar bending forces? If the animal lifted or pulled something from the water with its jaws, the bulk of the force ought to be lasting on the mandible.
The upper jaw would secure the hold, but it would not have to withstand the force induced by the weight of the animal, neither would it have to bite down with particularly large bite force (which also explains why Spinosaurus’ rostrum is almost the same width as it is deep, unlike in baryonychine snouts, which are tall and narrow by comparison).

Imo that’s a sufficient explanation (also for the seemingly deep mandible shape of Irritator), but I guess it’s a lumper/splitter thing...
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coherentsheaf
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theropod
Feb 11 2014, 01:22 AM
Would the rostrum actually be subject to similar bending forces? If the animal lifted or pulled something from the water with its jaws, the bulk of the force ought to be lasting on the mandible.
The upper jaw would secure the hold, but it would not have to withstand the force induced by the weight of the animal, neither would it have to bite down with particularly large bite force (which also explains why Spinosaurus’ rostrum is almost the same width as it is deep, unlike in baryonychine snouts, which are tall and narrow by comparison).

Imo that’s a sufficient explanation (also for the seemingly deep mandible shape of Irritator), but I guess it’s a lumper/splitter thing...
hm this would imply that far more bending force would come from lifting the animal than from biting on it. I suppose that is possible, though I would guess somewhat implausible. In this ase Spinosaurus would regularly prey on fish in excess of 1000 kg. I have a hard time picturing it.
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Vobby
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I dare say that since we all seem to agree about the fact that the holotype was smaller than Tyrannosaurus, and since it seems very very likely that Headden is right in saying that the Milan rostrum belongs to a different specie, this debate can end here. T. rex is bigger, it wins. When paleontologists will find other parts of the MSNM v4047 spinosaurine we will have another happy thread of more than 200 pages (I would be very disappointed of the contrary!).
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theropod
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Well, I’m talking about the spinosaurine specimen presumed to be the largest known theropod, and I guess everone else here is too. In a matchup holotype vs sue, I’d agree with you.

@coherentsheaf: I picture it doing that (if both are from the same species) on a somewhat regular basis.
Otherwise, neither could I make sense of how deep its dentary is (not just compared to the rostrum, but compared to itself), nor of the common association of Spinosaurus and Onchopristis remains (with Onchopristis body parts stuck in at least two Spinosaurus jaw fragments).
That a very large (and it is very large, no matter what of the stuff written about it one believes) piscivore evolved in a biota with several huge fish species also is a bit too much of a coincidence for me to believe it did not prey on them.
And finally, the rostrum is not that weak itself. It’s ~20cm deep, and seems to consist of very thick, compact bones. It may not be well-suited for biting down hard, but I doubt it would shatter when clamping onto a fish.

This seems to be a more likely option than that it had a disproportionally short dentary for a spinosaur, regardless of whether both were the same species or not.
Edited by theropod, Feb 11 2014, 04:41 AM.
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Vobby
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Well, I find that presumption possible, but still very weak. How can we really judge size from a rostrum? It is particularly elongated, did the same apply for the body? Is the size of its vertebrae similar to that of Spinosaurus? Did it had those neural spines? The possible reconstructions of the skull vary from 132 to 175 cm, how can we really judge which wis more plausible, since we don't even have decent remains of the skull of its, supposely, closest relative, Spinosaurus?

In short, I don't think it's the case to talk about a fight between T. rex and a virtually imaginary theropod. Maybe the reconstruction of the skull of MSNM v4047 deserves a proper thread...
Edited by Vobby, Feb 11 2014, 04:20 AM.
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