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Spinosaurus aegyptiacus v Tyrannosaurus rex
Topic Started: Jan 7 2012, 02:16 AM (459,201 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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Vobby
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Omnivore
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You are clearly much more informed than me, so I just can't debate with you about this topic, at least right now. But what do you think about the fact that his estimate (if it is. To me, it seems that he is more interested in denying the existence of 16-18 m spinosaurus) are confirmed by the work of Therrien & Henderson (2007)?
Edited by Vobby, Oct 6 2013, 03:49 AM.
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Jinfengopteryx
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The two estimates use completely different methods, so this is irrelevant (the Therrien & Henderson study is even worse BTW).
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SpinoInWonderland
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Vobby
Oct 6 2013, 03:48 AM
the work of Therrien & Henderson (2007)
...created the ~20-tonne Spinosaurus.
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ArachnidKid
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SpinoInWonderland
Oct 6 2013, 04:44 AM
Vobby
Oct 6 2013, 03:48 AM
the work of Therrien & Henderson (2007)
...created the ~20-tonne Spinosaurus.
Aha yes! the mere allegation causes some to salivate at the sight of it lol
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SpinoInWonderland
The madness has come back...
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ArachnidKid
Oct 6 2013, 05:01 AM
SpinoInWonderland
Oct 6 2013, 04:44 AM
Vobby
Oct 6 2013, 03:48 AM
the work of Therrien & Henderson (2007)
...created the ~20-tonne Spinosaurus.
Aha yes! the mere allegation causes some to salivate at the sight of it lol
Yeah, not knowing that such a creature would collapse!

Anyway this particular match-up is pointless, it would never end. Tapinocaninus would kill both
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Vobby
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SpinoInWonderland
Oct 6 2013, 04:44 AM
Vobby
Oct 6 2013, 03:48 AM
the work of Therrien & Henderson (2007)
...created the ~20-tonne Spinosaurus.
Really? Uhm. One guy in the comments of Cau's article said that this work confirmed its estimate, I guess he was wrong.
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SpinoInWonderland
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Vobby
Oct 6 2013, 05:08 AM
SpinoInWonderland
Oct 6 2013, 04:44 AM
Vobby
Oct 6 2013, 03:48 AM
the work of Therrien & Henderson (2007)
...created the ~20-tonne Spinosaurus.
Really? Uhm. One guy in the comments of Cau's article said that this work confirmed its estimate, I guess he was wrong.
Well, think about this:

A ~20-tonne Spinosaurus, at less than ~15 meters in length, is going to be very obese and would need a miracle to survive.

Don't trust everything you read online.
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Vobby
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Of course I don't. Cau answered to him saying that it was correct. I'll look better trough this.
Edited by Vobby, Oct 6 2013, 07:56 AM.
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theropod
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The estimates of Therrien & Henderson, 2007 are obviously fallacious, they base on a number of extremely oversimplified assumptions.

Besides them assuming Spinosaurus' skull to be 1.5m long for their lower figure, they produced their total lenght and total weight figures based on regressions that incorporate more or less only completely unrelated taxa (some of which are assumed to be the wrong lenght and/or weight on top of that). You can see consistent error of estimates in the animals that happen to be rather proportionally large skulled or small skulled respectively.

It's rather a negative point, especially in an unconventionally proportioned theropod like a spinosaurid, if your works are confirmed by such a methodology.

Of course any partisan of a smallish spinosaurus, or someone who, like Cau himself, is just strongly opposed to Spinosaurus being as large as commonly found can write a comment saying it confirmed the reasoning. That's not surprising since both estimates overlap on some crucial and imo quite fallacious points.
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Teratophoneus
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Vobby
Oct 6 2013, 12:43 AM
I just realized two things:
1) There is a very well documented blog dedicated only to theropods, and this blog is in Italian, my language, and this is wonderfull.
2) The author of this blog, Cau, states that Spinosaurus wasn't bigger than other theropods like Tyrannosaurus and Giganotosaurus.

So...
T. rex wins. Hands down. And I'm very happy.
Well, I'm italian too, and I know that Cau when talking about Spino's size he conisdered only the holotype. MSNM V4047 may haven't been neither a Spino. Spino's size is really doubftul, he may have been anything between 12 and 18 m.
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Spinodontosaurus
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Vobby
Oct 6 2013, 12:43 AM
I just realized two things:
1) There is a very well documented blog dedicated only to theropods, and this blog is in Italian, my language, and this is wonderfull.
2) The author of this blog, Cau, states that Spinosaurus wasn't bigger than other theropods like Tyrannosaurus and Giganotosaurus.

So...
T. rex wins. Hands down. And I'm very happy.

Hmm Scott Hartman himself is a palaeontologist who does literally produce rigorous skeletal reconstructions for a living.

In any case, Cau's most recent estimate of 12.6 meters based on vertebrae length 40% greater than that of Baryonyx. It just so happens that Hartman's 14 meter type specimen is also 40% longer than his own 10 meter Baryonyx; Hartman's is simply based on a slightly longer (and far newer) Baryonyx reconstruction, probably primarily in the tail.

An animal this size isn't going to be any bigger than the largest specimens of Tyrannosaurus or Giganotosaurus, no. But MSNM V4047 would, if Hartman has his skull reconstruction right, at 15.6 meters, and a weight advantage in the region of 40% by my reckoning.

Hartman too addressed the Irritator angle that Cau beats to death: http://www.skeletaldrawing.com/home/scaling-issues-a-minor-irritation712013
Regardless of the fact his reconstruction is over 20cm longer than the one Cau used from Dal Sasso et al. 2005, he rightly notes that absolute skull length isn't the deciding factor:
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Even better, it doesn't matter much for size estimates. Scaling my current Spinosaurus skull up to the size of the big MSMN snout yields a skull in the 163-164 cm range. Hacking off the back of Irritator's skull and pasting it onto the back of the same snout results in a head that is ~`158 cm... a difference of less than 4%.

A 4% difference in skull length translates to less than half a percent on the length of the entire animal - far less than the actual margin of error we have (mostly from unknowns in the tail length). Even better, it has no bearing on the mass estimates at all - the issue of whether the skull was a bit shorter or longer doesn't impact the torso length, that relationship is instead determined by the size of the head (and type mandible) to the type vertebrae.

We already know how big the dentary is compared to the vertebrae, and since MSNM V4047 is a rostrum, the important part is establishing how large the rostrum was in relation to the dentary. This is completely independent of the total skull length figure; it could be 130cm or 200cm and it wouldn't have any effect (bar the 70cm difference coming from the skull itself). Cau's 130cm skull would simply lower Hartman's length estimate by 30cm, to 15.3 meters.
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theropod
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from the theropod database:
Quote:
 
middle cervical vertebra (185 mm), four dorsal vertebrae (195, 170, ~190, ~210 mm) incomplete first sacral vertebra (155 mm), second sacral centrum, partial third sacral centrum, proximal caudal vertebra (90 mm)

Average of the four dorsals: 191.25mm

Quote:
 
third cervical (81 mm), fifth cervical (74 mm), sixth cervical (95 mm), eighth cervical (120 mm), three cervical ribs (one complete), first dorsal (91 mm), second dorsal (108 mm), third dorsal (92 mm), partial fourth dorsal including centrum, prezygopophysis and diapophysis (90 mm), fifth dorsal (92 mm), sixth dorsal (88 mm), seventh dorsal neural arch, eighth dorsal centrum (93 mm), tenth cervical neural arch, eleventh dorsal (105 mm), thirteenth dorsal centrum (108 mm), fourteenth dorsal (110 mm), many dorsal ribs, several gasteralia, proximal caudal (134 mm), proximal caudal (144 mm), proximal caudal (140 mm), three fragmentary caudal centra, proximal caudal neural arch

average of the 9 dorsals: 96.6mm

It's funny enough that based on the dorsal vertebrae the Spinosaurus holotype should be almost double the snout-ventral lenght of that of Baryonyx, and even based on the very longest of Baryonyx cervicals (which is posterior, not middle, the rest being in accordance with a >90% bigger animal) still more than 50% bigger.
The caudal is the only piece that seems oddly short (extremely short actually, might it be miscited?), so it could be quite short-tailed indeed, only meaning that it's very bulky for it's total lenght.
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theropod
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How much bigger MNSN v4047 is depends on the Rostrum-dentary scaling, for which several hypotheses have been made. It's quite complicated because the dentary has such an odd shape.
But the bigger it is proportionally, the bigger Dal Sasso's specimen will be compared to the holotype.20% are certainly not an unrealistic number.
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Spinodontosaurus
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Cau actually addressed the enormous difference in vertebrae size as he pointed out they aren't measured in the same way. It's where he got the 40% difference from, which is inline with Hartman's reconstructions too.

EDIT: Your long torso idea is also reflected in Hartman's reconstruction (seriously go have a look, it's torso is huge).
Edited by Spinodontosaurus, Oct 7 2013, 07:33 AM.
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theropod
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Are you impyling I didn't ever look at Hartmans Spinosaurus skeletal?
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