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Spinosaurus aegyptiacus v Tyrannosaurus rex
Topic Started: Jan 7 2012, 02:16 AM (459,349 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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Fragillimus335
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Jinfengopteryx
Sep 10 2012, 04:25 AM
I did that scale on my own already and I got the same result, but somehow the mentioned max weight is always*just*9t.
My honest belief is that the authors of the Spinosaurus paper were reluctant to publish such huge(but likely accurate)weights, for fear of being ridiculed.
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theropod
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12,3m is the actual lenght of sue, 12,8m was guess before it was mounted and they saw it´s tail wasn´t as long as they tought. sue is still not average size, average vs average spinosaurus has a huge weight advantage.

ignoring these two cases of possibly larger rexes, sue is still the largest, and it´s average is likely far below that.

And assuming 1,5m is MOR 005´s skull lenght, not mandible lenght (and the proportions seem really strange, the dentary is at parity not shorter than in sue while it should be, but MOR 008 has a proportionally longer mandible, so I suspect it is actually mandible lenght), there is no way it was more than 13,1m long. sue is 12,3, with a 1,4m skull. Mor is thus about 7% larger, that´s 13,1m
However I don´t see how it can be really as large as claimed by the media, it obviously has a shorter dentary and maxilla than sue, and it´s dentary isn´t shorter compared to total skull lenght. It´s mandible is probably 1,5m, that´s true. That in sue measures 1,53m tough, and this figure was often confused with its skull lenght.
UCMP 137538... we´ll see about that, but first we have to know whether there is actually a reason to believe it was really an IV-2. I just skimmed the paper, and it didn´t contain any mention of it as the largest T. rex, what one would expect in such a popular animal, neither did it give features suggesting this toes exact location in the foot.

But even a 13,1m T. rex would be tiny compared to the largest spinosaurus, and it doesn´t really matter that much whether it´s MOR 008, which is erraneously overhyped to be much bigger than sue while it is at best 0,8m longer if at all, is fighting an 18m spinosaurus or Sue is fighting it. they both are just simply too small compared to it.
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theropod
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Fragillimus335
Sep 10 2012, 04:19 AM
theropod
Sep 10 2012, 02:48 AM
yes it was a typing error, that´s true. yes, I regard the last solution as unlikely myself, but the other two are pretty likely.

fragillimus, what are the characters that are used to distinguish an IV-2 from another phalanx? are there any at all?

If there are any, they would probably be based on proportional robusticity, or the articulation planes between the bones. Which sadly is very hard to see in the limited number of photographs we have of these specimens.
sadly it´s only one bone, and robusticity varies a lot between T. rex specimens, not to mention a larger T. rex will always have proportionally more robust bones...
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theropod
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Fragillimus, you wrote you where studying in Iowa and one of your professors was involved in describing sue.
http://www.jstor.org/discover/10.2307/3889334?uid=3737528&uid=2134&uid=2&uid=70&uid=4&sid=21101033415853

I think I know whom you mean ;-)
Do you have acess to that paper? I couldn´t find any photos of sue´s phalanges, but I suspect the paper probably contains some.

it´d be interesting to see a comparison of UCMP 137538 and the pes of FMNH PR2081
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Ursus panthera
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The clear result is both may die.
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Fragillimus335
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theropod
Sep 10 2012, 04:50 AM
Fragillimus, you wrote you where studying in Iowa and one of your professors was involved in describing sue.
http://www.jstor.org/discover/10.2307/3889334?uid=3737528&uid=2134&uid=2&uid=70&uid=4&sid=21101033415853

I think I know whom you mean ;-)
Do you have acess to that paper? I couldn´t find any photos of sue´s phalanges, but I suspect the paper probably contains some.

it´d be interesting to see a comparison of UCMP 137538 and the pes of FMNH PR2081
Yup that's him, he's a great professor! I'll check the paper.
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Black Ice
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you say both will die here
yet you said an eland vs t-rex is 50/50
smh
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Ursus panthera
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Well the eland is powerful and seriously could have gave the t rex a run for its money.
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Black Ice
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Ursus panthera
Sep 10 2012, 05:05 AM
Well the eland is powerful and seriously could have gave the t rex a run for its money.
shake my head.
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Grey
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Ursus panthera
Sep 10 2012, 05:05 AM
Well the eland is powerful and seriously could have gave the t rex a run for its money.
You must be kidding !
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Ursus panthera
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I admit the t rex would win 60/40
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Fragillimus335
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theropod
Sep 10 2012, 04:50 AM
Fragillimus, you wrote you where studying in Iowa and one of your professors was involved in describing sue.
http://www.jstor.org/discover/10.2307/3889334?uid=3737528&uid=2134&uid=2&uid=70&uid=4&sid=21101033415853

I think I know whom you mean ;-)
Do you have acess to that paper? I couldn´t find any photos of sue´s phalanges, but I suspect the paper probably contains some.

it´d be interesting to see a comparison of UCMP 137538 and the pes of FMNH PR2081
Your wish is my command :D

Some great figures from the paper!!!
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And the mysterious UCMP 137538!
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Edited by Fragillimus335, Sep 10 2012, 05:19 AM.
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Grey
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Ursus panthera
Sep 10 2012, 05:11 AM
I admit the t rex would win 60/40
Seriously, an eland is absolutely NO MATCH for an adult Tyrannosaurus.

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Shaochilong
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Ursus panthera
Sep 10 2012, 05:11 AM
I admit the t rex would win 60/40
Against the eland or the Spinosaurus?
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Jinfengopteryx
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Lord of the Allosaurs
Sep 10 2012, 05:43 AM
Ursus panthera
Sep 10 2012, 05:11 AM
I admit the t rex would win 60/40
Against the eland or the Spinosaurus?
I guess the Eland.
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