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Spinosaurus aegyptiacus v Tyrannosaurus rex
Topic Started: Jan 7 2012, 02:16 AM (459,337 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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and it might not be a good idea to merely rely on caus thoughts here, when he is appearantly one of the people who imagine spinosaurus as only 12,5m long...
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Gecko
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Cau's estimate holds no less than the 18-19 m estimates...

The Das Sasso Spinosaurus was said to be at most 20% bigger. Even if the holotype was a subadult that doesn't mean it had another 4-5 meters left to grow (If that was the case I think it would be considered a juvenile)

Even the 12.5 m(Not that I think it's true but it certainly sounds better than 18 meters...) makes more sense than the 16 m+ estimates, from what we have seen all (no other ones, Spnosaurus is the only exception we know of) the giant theopods top out at 11-13 m long and 6-8 tons, why would Spinosaurus grow twice as big and 6-7 m longer?
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Fragillimus335
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Because it had a different lifestyle, it didn't have to run around as much as other large theropods.
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theropod
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Gecko
Oct 4 2012, 01:29 AM
Cau's estimate holds no less than the 18-19 m estimates...

The Das Sasso Spinosaurus was said to be at most 20% bigger. Even if the holotype was a subadult that doesn't mean it had another 4-5 meters left to grow (If that was the case I think it would be considered a juvenile)

Even the 12.5 m(Not that I think it's true but it certainly sounds better than 18 meters...) makes more sense than the 16 m+ estimates, from what we have seen all (no other ones, Spnosaurus is the only exception we know of) the giant theopods top out at 11-13 m long and 6-8 tons, why would Spinosaurus grow twice as big and 6-7 m longer?
It is not that much a matterr of whether it makes sense (which it does actually, and the other ones topping at around 13m is quite conservative itself), it´s a matter of evidence, and a spinosaur, a group which usually showed a relatively uniform 10/1 ratio, with a 1,75m head at only 12-14m.... that is a whole lot less likely than 18m if you ask me
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Verdugo
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theropod
Oct 4 2012, 01:00 AM
and it might not be a good idea to merely rely on caus thoughts here, when he is appearantly one of the people who imagine spinosaurus as only 12,5m long...
Actually, not only Cau but David Hone states that Spinosaurus would not be THAT big

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Gecko
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@ Fragillimus335 Carcharodontosaurids weren't too speedy either but yet they maxed out at that range (11-13 m)

@Theropod the only mostly complete Spinosaur we have is Baryonyx, Suchmimus is incomplete and so are most of the other Spinosaurs.

Just a question, have you tried scaling Daspletosaurus up to Tyrannosaurus based on skull size alone, because that's what you're doing with Spinosaurus? (Not trying to be mean but I'm curious to see what comes up)

@Verdugo nice find. I thought Cau's was the only one.
Edited by Gecko, Oct 4 2012, 02:47 AM.
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theropod
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still just the opinion and cautious approach of one person.
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theropod
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Gecko
Oct 4 2012, 02:43 AM
@ Fragillimus335 Carcharodontosaurids weren't too speedy either but yet they maxed out at that range (11-13 m)

@Theropod the only mostly complete Spinosaur we have is Baryonyx, Suchmimus is incomplete and so are most of the other Spinosaurs.

Just a question, have you tried scaling Daspletosaurus up to Tyrannosaurus based on skull size alone, because that's what you're doing with Spinosaurus? (Not trying to be mean but I'm curious to see what comes up)
Carcharodontosaurs had an active predatory lifestyle and they hunted large terrestrial prey. This required them to be speedy, even though they wheren´t the quickest animals...


yeah, scaling up daspletosaurus I get 12,6m. the difference is ignorable actually
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Gecko
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What is the equation you are using? Maybe try Albertosaurus instead as that is closer to the difference between Spinosaurus and Baryonyx.
Edited by Gecko, Oct 4 2012, 02:56 AM.
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theropod
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(9/1)*1,4

9m: lenght of daspletosaurus
1m: lenght of it´s skull
1,4m: lenght of sues skull

I don´t think albertosaurus is a good comparison, after all it is evidently far more cursorial also compared to the similar sized daspletosaurus, which cannot be said about baryonyx.

correction:
(9/1,04)*1,4=12,1m

but here you are:

RTMP 81.10.1) (8 m; 1.14 tons; 24 year old adult) partial skull (970 mm

(8/0,97)*1,4=11,5m

Seems to produce a rather low estimate actually. so far I haven´t read any real reson to suspect a PISCIVORE to be only 70% of the lenght predicted by isometric scaling from it´s relatives.





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Gecko
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Baryonyx has a 1/9 ratio (9 meters, 1 m skull) right? Suchomimus has a 1/8.4 ratio (1.3 m skull, 11 m). So why couldn't Spinosaurus have a 1.75 skull and be 13-16 m long? Where did the 1/10 ratio come from?

Using Baryonyx you get 15.75 m. Using Suchomimus you get 14.7 m.
Edited by Gecko, Oct 4 2012, 03:36 AM.
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theropod
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baryonyx is 9,1m and has a 0,915 m skull, sucho is 11m and has a skull supposedly 1,18m long. very close to a 10/1 ratio
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Gecko
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The .915 m is for the incomplete skull of Baryonyx, the full skull would have been 1 m. The my theropod is bigger than yours gives suchomimus a 1.19 m skull, and 10.34 m for total length. Both are around a 1/8-1/9 ratio not 1/10.
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Fragillimus335
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Albertosaurus scales up perfectly too. A 30 foot Alberto has a 3.3 foot long skull. 4.5/3.3=1.36. 1.36x30= 40.8 feet for T-rex.
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Gecko
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Using the "My Theropod is bigger than your Theropod" paper gives Baryonyx a .91 m skull and a TL of 8.19 m, it gives Suchmimus a 1.19 m skull and a TL of 10.31 m. So still no 1/10 ratio (Even if it was that it would have been mostly tail length.) Using those Spinosaurus goes in the 15-16 m range not 18 m. Which is what everyone except Dal Sass says.
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