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Spinosaurus aegyptiacus v Tyrannosaurus rex
Topic Started: Jan 7 2012, 02:16 AM (459,093 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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Thalassophoneus
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Nov 11 2015, 06:34 AM
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Nov 11 2015, 04:37 AM
My estimates are approximate. I used both Baryonyx and Suchomimus cause their skulls had proportionally different size, so having the overall length of MSNM V4047 I could use it to measure the rest of the creature. I fell close to Dal Sasso with Baryonyx and again at over 15 m. with Suchomimus.
Scaling up from relatives is only recommended if too little is known for any other method.
Simple scaling is just too unreliable to be used if better evidence is present.
What else can somebody do right now? Spinosaurids aren't well preserved.
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Spinodontosaurus
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I assume that this indeterminate spinosaurid you were tlaking about is Sigilmassasaurus.

No, it is an indeterminate spinosaurid, not Sigilmassasaurus. MSNM V4047 cannot be referred to Sigilmassasaurus for the same reasons it cannot be referred to Spinosaurus. If future discoveries show us that, actually, the snout is indeed from a Spinosaurus then great, but unless that happens it cannot be considered a Spinosaurus.

Also note that the preserved part of MSNM V4047 is actually 98.8 cm. This seems like an insignificant difference, and to be honest it is, but it explains why you are getting a smaller skull length estimate that Dal Sasso et al. did despite using an identical skull reconstruction.

EDIT: Also how are you getting an estimate in excess of 15 meters by using Suchomimus? Even MSNM V4047 is only 22% larger than it, which yields a total length of roughly 14.2 meters.
Edited by Spinodontosaurus, Nov 11 2015, 12:05 PM.
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Thalassophoneus
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Nov 11 2015, 12:04 PM
Quote:
 
I assume that this indeterminate spinosaurid you were tlaking about is Sigilmassasaurus.

No, it is an indeterminate spinosaurid, not Sigilmassasaurus. MSNM V4047 cannot be referred to Sigilmassasaurus for the same reasons it cannot be referred to Spinosaurus. If future discoveries show us that, actually, the snout is indeed from a Spinosaurus then great, but unless that happens it cannot be considered a Spinosaurus.

Also note that the preserved part of MSNM V4047 is actually 98.8 cm. This seems like an insignificant difference, and to be honest it is, but it explains why you are getting a smaller skull length estimate that Dal Sasso et al. did despite using an identical skull reconstruction.

EDIT: Also how are you getting an estimate in excess of 15 meters by using Suchomimus? Even MSNM V4047 is only 22% larger than it, which yields a total length of roughly 14.2 meters.
What kind of proof do we need that it was from Spinosaurus? I mean besides from the fact that it looks exactly like it is from a Spinosaurus and that due to this reason about everyone believes it was from a Spinosaurus. Cause as you said by yourself even this one source you posted is indirect proof that it MIGHT not have been from a Spinosaurus.

As you might have realized your source still hasn't convinced me. It never will cause it basically tells you that you took an apple from a tree that had another rotten apple.


I do length of Spinosaurus skull/length of other dinosaur skull and then I multiply this with the length of the other dinosaur. If I remember well I did this twice both with Baryonyx and with Suchomimus to ensure there were no errors during the calculation. You can see the results.
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DarkGricer
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Nov 11 2015, 10:29 PM
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Nov 11 2015, 12:04 PM
Quote:
 
I assume that this indeterminate spinosaurid you were tlaking about is Sigilmassasaurus.

No, it is an indeterminate spinosaurid, not Sigilmassasaurus. MSNM V4047 cannot be referred to Sigilmassasaurus for the same reasons it cannot be referred to Spinosaurus. If future discoveries show us that, actually, the snout is indeed from a Spinosaurus then great, but unless that happens it cannot be considered a Spinosaurus.

Also note that the preserved part of MSNM V4047 is actually 98.8 cm. This seems like an insignificant difference, and to be honest it is, but it explains why you are getting a smaller skull length estimate that Dal Sasso et al. did despite using an identical skull reconstruction.

EDIT: Also how are you getting an estimate in excess of 15 meters by using Suchomimus? Even MSNM V4047 is only 22% larger than it, which yields a total length of roughly 14.2 meters.
What kind of proof do we need that it was from Spinosaurus? I mean besides from the fact that it looks exactly like it is from a Spinosaurus and that due to this reason about everyone believes it was from a Spinosaurus. Cause as you said by yourself even this one source you posted is indirect proof that it MIGHT not have been from a Spinosaurus.

As you might have realized your source still hasn't convinced me. It never will cause it basically tells you that you took an apple from a tree that had another rotten apple.


I do length of Spinosaurus skull/length of other dinosaur skull and then I multiply this with the length of the other dinosaur. If I remember well I did this twice both with Baryonyx and with Suchomimus to ensure there were no errors during the calculation. You can see the results.
The proof we need is an overlap of fossil material. If we had found MSNM V4047 upper jaw right next to a lower jaw or vertebrae that looked pretty much identical to that of the holotype, then we can safely assume that it was indeed a Spinosaurus. But as it is, we simply assign it to Spinosaurus because there is no KNOWN alternative, but that doesn't mea that MSNM V4047 cannot be the holotype of an entirely new species.

And yes, you did make an error in your calculation, namely using a 1.7 meter + skull for Spinosaurus when it has already established that Spinosaurus' skull almost certainly did not exceed 1.6 meters.
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blaze
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"But as it is, we simply assign it to Spinosaurus because there is no KNOWN alternative"

That should have been in past tense, now we know there are more than one taxon in both Kem Kem and Bahariya (so at least 2, possibly 4 alternatives) but back then, Dal Sasso et al. (2005), just as Ibrahim et al. (2014) did, lumped everything into Spinosaurus aegyptiacus.
Edited by blaze, Nov 12 2015, 12:32 AM.
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Thalassophoneus
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Nov 11 2015, 10:59 PM
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Nov 11 2015, 12:04 PM

Quoting limited to 3 levels deepSigilmassasaurus. MSNM V4047 cannot be referred to Sigilmassasaurus for the same reasons it cannot be referred to Spinosaurus. If future discoveries show us that, actually, the snout is indeed from a Spinosaurus then great, but unless that happens it cannot be considered a Spinosaurus.

Also note that the preserved part of MSNM V4047 is actually 98.8 cm. This seems like an insignificant difference, and to be honest it is, but it explains why you are getting a smaller skull length estimate that Dal Sasso et al. did despite using an identical skull reconstruction.

EDIT: Also how are you getting an estimate in excess of 15 meters by using Suchomimus? Even MSNM V4047 is only 22% larger than it, which yields a total length of roughly 14.2 meters.
What kind of proof do we need that it was from Spinosaurus? I mean besides from the fact that it looks exactly like it is from a Spinosaurus and that due to this reason about everyone believes it was from a Spinosaurus. Cause as you said by yourself even this one source you posted is indirect proof that it MIGHT not have been from a Spinosaurus.

As you might have realized your source still hasn't convinced me. It never will cause it basically tells you that you took an apple from a tree that had another rotten apple.


I do length of Spinosaurus skull/length of other dinosaur skull and then I multiply this with the length of the other dinosaur. If I remember well I did this twice both with Baryonyx and with Suchomimus to ensure there were no errors during the calculation. You can see the results.
The proof we need is an overlap of fossil material. If we had found MSNM V4047 upper jaw right next to a lower jaw or vertebrae that looked pretty much identical to that of the holotype, then we can safely assume that it was indeed a Spinosaurus. But as it is, we simply assign it to Spinosaurus because there is no KNOWN alternative, but that doesn't mea that MSNM V4047 cannot be the holotype of an entirely new species.

And yes, you did make an error in your calculation, namely using a 1.7 meter + skull for Spinosaurus when it has already established that Spinosaurus' skull almost certainly did not exceed 1.6 meters.
Quote:
 
The proof we need is an overlap of fossil material. If we had found MSNM V4047 upper jaw right next to a lower jaw or vertebrae that looked pretty much identical to that of the holotype, then we can safely assume that it was indeed a Spinosaurus. But as it is, we simply assign it to Spinosaurus because there is no KNOWN alternative, but that doesn't mea that MSNM V4047 cannot be the holotype of an entirely new species.


Quote:
 
But as it is, we simply assign it to Spinosaurus because there is no KNOWN alternative, but that doesn't mea that MSNM V4047 cannot be the holotype of an entirely new species.


You guys have repeatedly told me not to assume something without proof. Now you assume that MSNM V4047 MIGHT haven't belonged to a Spinosaurus with your only proof being that someone recently suggested that the bones from that area SEEM to have belonged to different dinosaurs. At the same time I assume it did belong to a Spinosaurus and my clear proof is that this is how it looks like.

In other words, as most paleontologists agree that it belonged to a Spinosaurus, and this is how it looks like, until you find clear evidence that it didn't, we just keep assuming that it belonged to a Spinosaurus.

Quote:
 
And yes, you did make an error in your calculation, namely using a 1.7 meter + skull for Spinosaurus when it has already established that Spinosaurus' skull almost certainly did not exceed 1.6 meters.


Circular reasoning. You ignore past arguments of mine and as a result I have to mention them again.

I tried to measure the approximate length of the full skull of MSNM V4047 by myself, using paint. I would suggest you to read above.
blaze
Nov 12 2015, 12:32 AM
"But as it is, we simply assign it to Spinosaurus because there is no KNOWN alternative"

That should have been in past tense, now we know there are more than one taxon in both Kem Kem and Bahariya (so at least 2, possibly 4 alternatives) but back then, Dal Sasso et al. (2005), just as Ibrahim et al. (2014) did, lumped everything into Spinosaurus aegyptiacus.
Yes... the reason they did that is that it looks like they all actually belonged to Spinosaurus Aegyptiacus. I'm not sure whether they actually belonged to different species, which would possibly mean that Ibrahim's reconstruction was a chimera. But it is almost certain they all belonged to a Spinosaurus. And if things are this way then MSNM V4047 belonged to a Spinosaurus, and since it is one bone it belonged to one specimen and we can use its size to calculate the possible maximum size of that Spinosaurus.
Edited by Thalassophoneus, Nov 12 2015, 02:50 AM.
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blaze
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Quote:
 
Yes... the reason they did that is that it looks like they all actually belonged to Spinosaurus Aegyptiacus. I'm not sure whether they actually belonged to different species, which would possibly mean that Ibrahim's reconstruction was a chimera. But it is almost certain they all belonged to a Spinosaurus. And if things are this way then MSNM V4047 belonged to a Spinosaurus, and since it is one bone it belonged to one specimen and we can use its size to calculate the possible maximum size of that Spinosaurus.


They reason they did that is because they assumed they are well Spinosaurus, despite not really having any evidence of that being the case because of the lack of overlapping material for most of those remains, Dal Sasso at al. (2005), just like Ibrahim et al. (2014) literally spend a couple of lines justifying those referrals. Evers et al. (2015) did a far far more rigorous work (the paper is over 100 pages long!) at looking at the osteology of the vertebrae and comparing it to relatives, it does not seem like there is another taxon in the mix, it almost certainly is, Sigilmassasaurus doesn't even group with Spinosaurus type or the new specimen in Cau's phylogenetic analyses and when scored alone neither does MSNM V4047,Link it jumps all over the place, suggesting that yes, we can't classify it beyond Spinosaurinae indet.
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Thalassophoneus
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blaze
Nov 12 2015, 03:36 AM
Quote:
 
Yes... the reason they did that is that it looks like they all actually belonged to Spinosaurus Aegyptiacus. I'm not sure whether they actually belonged to different species, which would possibly mean that Ibrahim's reconstruction was a chimera. But it is almost certain they all belonged to a Spinosaurus. And if things are this way then MSNM V4047 belonged to a Spinosaurus, and since it is one bone it belonged to one specimen and we can use its size to calculate the possible maximum size of that Spinosaurus.


They reason they did that is because they assumed they are well Spinosaurus, despite not really having any evidence of that being the case because of the lack of overlapping material for most of those remains, Dal Sasso at al. (2005), just like Ibrahim et al. (2014) literally spend a couple of lines justifying those referrals. Evers et al. (2015) did a far far more rigorous work (the paper is over 100 pages long!) at looking at the osteology of the vertebrae and comparing it to relatives, it does not seem like there is another taxon in the mix, it almost certainly is, Sigilmassasaurus doesn't even group with Spinosaurus type or the new specimen in Cau's phylogenetic analyses and when scored alone neither does MSNM V4047,Link it jumps all over the place, suggesting that yes, we can't classify it beyond Spinosaurinae indet.
You are telling me that a rostrum that looks exactly like that of a Spinosaurus isn't actually that of a Spinosaurus.

Even if it is that way and the bones in Kem Kem belonged to different spinosaurids, why does this necessarily mean that MSNM V4047 didn't belong to a Spinosaurus? Maybe MSNM V4047 did belong to a Spinosaurus while other bones, like thsoe vertebrae that you mentioned, did not. The fact that some vertebrae (and possibly other bones) look different from those of a Spinosaurus doesn't mean that even the bones that look like those of a Spinosaurus didn't belong to one just because they were from the same area.
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DarkGricer
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Nov 12 2015, 03:45 AM
You are telling me that a rostrum that looks exactly like that of a Spinosaurus isn't actually that of a Spinosaurus.
That statement does not even make any sense. Unless you count MSNM V4047 as a Spinosaurus, there is no known Spinosaurus rostrum, because MSNM V4047 IS the rostrum all reconstruction are based on. There is no overlapping material between MSNM V4047 and any known Spinosaurus specimen, hence why it cannot be referred to Spinosaurus.
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Thalassophoneus
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Nov 12 2015, 05:36 AM
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You are telling me that a rostrum that looks exactly like that of a Spinosaurus isn't actually that of a Spinosaurus.
That statement does not even make any sense. Unless you count MSNM V4047 as a Spinosaurus, there is no known Spinosaurus rostrum, because MSNM V4047 IS the rostrum all reconstruction are based on. There is no overlapping material between MSNM V4047 and any known Spinosaurus specimen, hence why it cannot be referred to Spinosaurus.
Aren't all the other rostra that are attributed to Spinosaurus and look like MSNM V4047 proof that MSNM V4047 belonged to a Spinosaurus?

Quote:
 
Unless you count MSNM V4047 as a Spinosaurus, there is no known Spinosaurus rostrum, because MSNM V4047 IS the rostrum all reconstruction are based on.


There are both other rostrums and other skull parts. There is UCPC-2, MNHN SAM 124, BM231 and BSP 1912 VIII 19. There is also FSAC-KK 11888, Ibrahim's specimen which contains skull fragments. If they seem to compose different parts of identical skulls then they should all be attributed to Spinosaurus.

At this point I would like to quote this.

Quote:
 
Sigilmassasaurus doesn't even group with Spinosaurus type or the new specimen in Cau's phylogenetic analyses and when scored alone neither does MSNM V4047


Why not? If it looks like other rostra that have belonged to Spinosaurus specimens then it was also a Spinosaurus specimen. Like how I said above.
As you can see, there is enough proof to ensure that we definitely know how Spinosaurus, or at least its skull, looked like so that we can recognise a skull as the skull of a Spinosaurus or a different species.

And I repeat, the fact that MSNM V4047 was found in an area with other spinosaurid bones that might not have belonged to Spinosaurus specimens isn't contradicted to the statement that this specific bone looks like it belonged to a Spinosaurus so it MUST have belonged to a Spinosaurus.
Edited by Thalassophoneus, Nov 12 2015, 06:15 AM.
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SpinoInWonderland
Aug 26 2012, 12:19 PM
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brolyeuphyfusion
Aug 10 2012, 01:15 AM
Just wait for my completely unbiased "Largest Theropods Size Comparison", and it will be way better than Prehistoric Cat's size comparisons combined!!! I'll be using Scott Hartman's skeletals, so it will be accurate...
Hey, whens it done
it's almost done, I'm just putting the labels/info in, and trying to find a good image of Ekrixinatosaurus
yet again where is the comparison
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Yet again? From where originally?

Seriously, stop with the replies to old-@$$ posts. If a >3 year old commitment to make a measly size comparison with giant theropods for the sake of some forum users hasn't been honored, it's not a big deal.
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blaze
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@Dunkleosteus Gigas

BSP 1912 VIII 19 from Egypt, incomplete dentary. <-- Only illustrated skull remains from the holotype

MSNM V4047 from Morocco, incomplete rostrum.
UCPC-2 from Morocco, piece of nasals with a crest.
FSAC-KK 11888 From Morocco, cranial bones preserved, pieces of prefrontal, nasals, squamosal, quadratojugal, quadrates, maybe lacrimal and surungular (erroneously referred as "dentary" in text but the figures prove otherwise).
MNHN SAM 124 From Algeria, an even less complete rostrum.
BM231 From Tunisia, an small piece of dentary.

Notice that save for BM 231, none of those specimens has bones that overlap with the holotype of Spinosaurus, excluding FSAC-KK 11888, the only reason every single one of those specimens was included in Spinosaurus in the past was because of the assumption that there was a single valid spinosaurid in Cenomanian North Africa, thanks to Evers et al. (2015) we know that's not the case, there's at least Sigilmassasaurus (also from Morocco) therefore none of those isolated specimens can be referred with confidence to either Sigilmassasaurus or Spinosaurus, what we have been arguing is not exclusive to MSNM V4047.


That's why DarkGricer said your statement about it looking like an Spinosaurus rostrum made no sense, neither the holotype or the new specimens preserves a rostrum so how can MSNM V4047 look like something that doesn't exist? And the same goes for SAM 124.


I recommend that you read this, Link, it's a blog post from Jaime Headden arguing that MSNM V4047 either actually comes from an animal no larger than the holotype (and Andrea Cau agrees) or belongs to a distinct taxon with a more gracile snout than that of the true Spinosaurus, the discrepancy between both jaw fragments is something recognized by Sereno and co. because they mentioned how they spend weeks figuring out how to fit them.

Edit:
Using the image here of the digital skull created by Sereno Labs and the drawings/photos of the holotype mandible and MSNM V4047 I discovered something interesting, they barely changed the scale of the holotype mandible.
Edited by blaze, Nov 12 2015, 10:15 AM.
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Nov 12 2015, 06:11 AM
DarkGricer
Nov 12 2015, 05:36 AM
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Nov 12 2015, 03:45 AM
You are telling me that a rostrum that looks exactly like that of a Spinosaurus isn't actually that of a Spinosaurus.
That statement does not even make any sense. Unless you count MSNM V4047 as a Spinosaurus, there is no known Spinosaurus rostrum, because MSNM V4047 IS the rostrum all reconstruction are based on. There is no overlapping material between MSNM V4047 and any known Spinosaurus specimen, hence why it cannot be referred to Spinosaurus.
Aren't all the other rostra that are attributed to Spinosaurus and look like MSNM V4047 proof that MSNM V4047 belonged to a Spinosaurus?

Quote:
 
Unless you count MSNM V4047 as a Spinosaurus, there is no known Spinosaurus rostrum, because MSNM V4047 IS the rostrum all reconstruction are based on.


There are both other rostrums and other skull parts. There is UCPC-2, MNHN SAM 124, BM231 and BSP 1912 VIII 19. There is also FSAC-KK 11888, Ibrahim's specimen which contains skull fragments. If they seem to compose different parts of identical skulls then they should all be attributed to Spinosaurus.

At this point I would like to quote this.

Quote:
 
Sigilmassasaurus doesn't even group with Spinosaurus type or the new specimen in Cau's phylogenetic analyses and when scored alone neither does MSNM V4047


Why not? If it looks like other rostra that have belonged to Spinosaurus specimens then it was also a Spinosaurus specimen. Like how I said above.
As you can see, there is enough proof to ensure that we definitely know how Spinosaurus, or at least its skull, looked like so that we can recognise a skull as the skull of a Spinosaurus or a different species.

And I repeat, the fact that MSNM V4047 was found in an area with other spinosaurid bones that might not have belonged to Spinosaurus specimens isn't contradicted to the statement that this specific bone looks like it belonged to a Spinosaurus so it MUST have belonged to a Spinosaurus.
Gotta love that circular reasoning.
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blaze
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I forgot to add that, even if that rostrum does turn out to be Spinosaurus, it doesn't mean at all that the 18m giant microcephalic Spinosaurus was a reality.
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