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Carcharodontosaurus saharicus

Canada DinoFan83 Offline
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#1
( This post was last modified: 07-15-2021, 06:11 PM by DinoFan83 )

Carcharodontosaurus is a genus of carnivorous carcharodontosaurid dinosaur that existed during the Cenomanian stage of the mid-Cretaceous period. It is currently known to have been among the largest theropods found, with known specimens significantly larger than Tyrannosaurus rex and on par with or approaching the estimated body mass for Giganotosaurus and Spinosaurus
The genus Carcharodontosaurus is named after the shark genus Carcharodon. itself composed of the Greek karchar[os] ( meaning "jagged" or "sharp") and odōn ("teeth"), and the suffix -saurus ("lizard"). Carcharodontosaurus includes some of the longest and heaviest known carnivorous dinosaurs, with various scientists proposing length estimates for the species. Based on relatives such as Giganotosaurus, the neotype of Carcharodontosaurus (SGM-DIN 1) would have been roughly 13-13.7 meters long and 9000-9800 kg. But this specimen was only a subadult, so adults would have been even larger.
Carcharodontosaurus were carnivores, with enormous jaws and sharp, serrated teeth (just like those of sharks, hence the same) up to 20 cm long. A skull length of over 1.6 meters has been restored for C. saharicus. In 2001, Hans C. E. Larsson published a description of the inner ear and endocranium of Carcharodontosaurus saharicus. Starting from the portion of the brain closest to the tip of the animal's snout is the forebrain, which is followed by the midbrain. The midbrain is angled downwards at a 45-degree angle and towards the rear of the animal. This is followed by the hindbrain, which is roughly parallel to the forebrain and forms a roughly 40-degree angle with the midbrain. 

Overall, the brain of C. saharicus would have been similar to that of a related dinosaur, Allosaurus fragilis. Larsson found that the ratio of the cerebrum to the volume of the brain overall in Carcharodontosaurus was typical for a reptile. Carcharodontosaurus also had a large optic nerve.
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( This post was last modified: 09-01-2021, 07:26 AM by DinoFan83 )

Carcharodontosaurus by Daitengu on DeviantArt.

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Carcharodontosaurus by Dmitry Bogdanov.

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Carcharodontosaurus by Fred Wierum.

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Carcharodontosaurus by SpinoInWonderland (>13.2 meters, >9000 kg).

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Carcharodontosaurus by GetAwayTrike (13.4 meters TL, >9400 kg).

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Carcharodontosaurus based on Giganotosaurus femur scaling by Oktaytanhu (ignore the given weights, however, as SGM-DIN 1 would have been >9000 kg at this length).

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Carcharodontosaurus based on Giganotosaurus done by Spinodontosaur4. Ignore the Triceratops.
(However, note that this uses the underestimated Scott Hartman Giganotosaurus, and using the fixed Giganotosaurus skeletals by Greg Paul, SpinoInWonderland, and GetAwayTrike would yield a >9000 kg animal given the 13.1 meter estimate).

*This image is copyright of its original author

Carcharodontosaurus skulls by Theropod1.

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Carcharodontosaurus skulls by SpinoInWonderland (IPHG 1922 X 46 is 135 cm and SGM-DIN 1 is 161 cm here).

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Carcharodontosaurus skull from Sereno et al. 1996 (>160 cm).

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Mounted Carcharodontosaurus skull by Franko Fonseca.

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Canada DinoFan83 Offline
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#3
( This post was last modified: 06-01-2021, 01:56 AM by DinoFan83 )

Large specimens of Carcharodontosaurus and Purussaurus. The latter restoration is also by Jorge W. Moreno-Bernal.

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SGM-DIN 1 (>9000 kg) and MSNM v4047 (13700 kg). 

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( This post was last modified: 06-01-2021, 01:55 AM by DinoFan83 )

Carcharodontosaurus tooth by Gyik Toma.

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Carcharodontosaurus by EmperorDinoBot.

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Carcharodontosaurus from Planet Dinosaur.

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Carcharodontosaurus from Dinosaur Planet.

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Italy Spalea Offline
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#5

" Carcharodontosaurus saharicus vs Human skull comparison ?

Via University of Chicago
Carcharodontosaurus is a genus of carnivorous carcharodontosaurid dinosaurs that existed during the Cenomanian stage of the mid-Cretaceous Period. It is currently known to include two species: C. saharicus and C. iguidensis, which were among the larger theropods, nearly as large as or even larger than Tyrannosaurus, Giganotosaurus and Spinosaurus.
Length: 8 – 14 m
Mass: 6,000 – 15,000 kg
Lived: 145 million years ago - 72.1 million years ago (Berriasian - Campanian) "


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Canada DinoFan83 Offline
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#6
( This post was last modified: 11-07-2021, 05:01 AM by DinoFan83 )

Here are some estimates I have done for Carcharodontosaurus size, based on Giganotosaurus/Tyrannotitan and a couple of different best fits between the holotype and neotype. I've deleted the old post on the matter and redid these from the ground up.

Femur estimate based on Giganotosaurus:

According to Carrano et al. (2012), the femur of MUCPv-Ch1 is 136 cm long, compared to 126 for IPHG 1922 X 46. As for the size of the Giganotosaurus being used as a base, I'll quote myself from elsewhere:

Quote:On his website, Paul estimates the Giganotosaurus holotype at 6850 kg. However, there are 2 issues with his skeletal likely underscoring the mass: 
-He has used a specific gravity of 0.85 when it should have been about 0.915 following Hartman's 2013 GDI analysis.
-In his skeletal, the preserved scapula is taken as complete when it isn't (the same issue that plagues Hartman's skeletal), thus making the chest much shallower than it would be. The correction factor, following both SpinoInWonderland's GDI of GetAwayTrike's Giganotosaurus as well as the GDI of his own skeletal, is 6800 to 7530 kg.
Correcting both of these, Greg Paul's skeletal of Giganotosaurus goes to 8170 kg for MUCPv-Ch1 (and it is about 12.46 meters long for the holotype).

This would result in a size of about 11.6 meters and 6500 kg for IPHG 1922 X 46. As for how to size up SGM-DIN 1, there are numerous plausible discrepancies between the holotype and the neotype, and they are as follows:

-Franoys' best estimate: 12.5% larger linearly.
-SpinoInWonderland's best estimate: 19.3% larger linearly
-Theropod1's best estimate: 20% larger linearly.
-Thedinorocker's best estimate: 26% larger linearly.

In order to prove a point that is elaborated on below*, I'll use Franoys' 12.5% discrepancy. This would result in a size of about 13 meters and 9250 kg for SGM-DIN 1 (6500x1.125^3).

SpinoInWonderland has been able to get similar weights to these using his Giganotosaurus skeletal (which is 12.4 meters for MUCPv-Ch1, meaning 11.5 meters for IPHG 1922 and 13.7 meters for SGM-DIN 1). To quote him:

Quote:I get about ~5.79 tonnes for IPHG 1922 X 46 if scaled based on my unreleased GDI for the old version of my Giganotosaurus skeletal (around ~7.4 tonnes, the deeper chest did quite a bit). Scaling this result up to SGM-Din 1 gives around ~9.8 tonnes (using my best-fit scaling factor).

So judging by this, SGM-DIN 1 is in the region of 13-13.7 meters and 9250-9800 kg if based on Giganotosaurus.

Using a different best fit:

Hard as it may be to believe for some, the only major difference between Franoys' and SpinoInWonderland's skeletals (the latter being quite larger at over 13.2 meters and >9000 kg) is the size difference they got between the holotype and the neotype (as you can see what I noted above) - aside from that, they both used Tyrannotitan and Giganotosaurus as the primary basis.

You could in fact use Franoys' skeletal but use thedinorocker's best fit of 26% between the holotype and neotype, and get 13.5 meters and 9660 kg for SGM-DIN 1.
Which brings me to my next point - Franoys' reasoning for their size estimate, often cited by those who believe in it, is faulty. Even though it may not appear so at face value.

https://www.deviantart.com/franoys/journ...-661837965

Quote:The missing elements are based on Tyrannotitan, the animal that is most closely related to Carcharodontosaurus according to the latest phylogenetic analysis (Canale 2014) and also one that shares with it a bunch of very interesting characters that will be discussed in another journal. Carcharodontosaurus is NOT out of the clade that bounds Tyrannotitan, Giganotosaurus , and Mapusaurus togheter, it is in fact strongly bounded to them in Carcharodontosaurinae, a clade of derived, giant Gondwanan Carcharodontosaurids, even if another smaller clade, Giganotosaurini, bound the south american Carcharodontosaurines even more strongly. 

Carcharodontosaurus is barely any bigger than Tyrannotitan in linear dimensions according to how most of the bones compare, the Carcharodontosaurus holotype has a femur smaller than that of the Tyrannotitan holotype, it's extrapolation to SGM din 1 size is barely any bigger than the same element in Tyrannotitan paratype, and the jugal of the Tyrannotitan paratype fits almost perfectly in SGM din 1 skull. Here it is scaled to be a vague (and optimistic) 0.5% bigger in linear dimensions based on marginal differences, and is also given a slightly lengthier tail to fit the only known caudal of the Carcharodontosaurus' holotype better.

Their reasons for their size estimate are that the size and proportions match up with (what they got for) the closely related Tyrannotitan. But what we see in modern animals directly disproves that phylogeny is a good predictor of size and proportions, as will be elaborated on below:

-The silver arowana and the Asian bonytongue are both members of the Osteoglossinae, just as Carcharodontosaurus and Tyrannotitan are both members of the Carcharodontosaurinae. Yet their fin proportions do have significant differences, with the Asian bonytongue having a proportionally much larger caudal fin (as can be clearly seen in the linked images).
-The harlequin shark and the black shark are both members of the genus Labeo (making them even more closely related to each other than Carcharodontosaurus is to Tyrannotitan). But according to Practical Fishkeeping, the harlequin shark only reaches 15 cm while the black shark reaches 90 cm. 

Quote:Name: Black shark
Scientific name: Labeo chrysophekadion.
Origin: Thailand.
Size: Up to 90cm.

Quote:Name: Harlequin shark.
Scientific name: Labeo cyclorhynchus.
Origin: Democratic Republic of the Congo (DRC) and Gabon, Africa.
Size: 15cm.

-And for a dual disproving, Mystus bocourti belongs to the same genus as Mystus bleekeri (making them even more closely related to each other than Carcharodontosaurus is to Tyrannotitan). But it is much larger and has a very differently proportioned dorsal fin+caudal fin.


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Quote:240mm SL


https://www.planetcatfish.com/common/spe...ies_id=967


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Quote:155mm SL

https://www.planetcatfish.com/common/spe...es_id=4006

So when looking at what we see in modern animals, literally no reason at all exists to believe Carcharodontosaurus' phylogeny had anything to do with its size or proportions.

That is not all - there is in fact evidence that Franoys' 12.5% best fit (and therefore their size estimate) is likely an underestimate, as the mean of all the listed best fits (19.5%) is very close to SpinoInWonderland's and very different from Franoys'. The average of these multiple best fits from several different authors therefore supports larger sizes.
Because of this, I would argue that SpinoInWonderland's estimate and using thedinorocker's best fit on Franoys' skeletal are both more likely to be correct than Franoys' original estimate despite being so much larger. 
This should be an important consideration for anyone who thinks SpinoInWonderland's size estimates and/or my size estimates are 'too large', 'inaccurate', 'older estimates', or 'outdated' because they are so much greater than the estimate from Franoys. If anything, like stated above, Franoys' estimate is not very accurate compared to SpinoInWonderland's/my estimates because it does not take into account factors (eg: what phylogeny actually means for proportions/size and the most probable best fits) that they do.

*Even when using Franoys' best fit, it's very possible to get a result right on par with the estimates derived from more plausible best fits (ergo: the femoral length estimate based on Greg Paul's Giganotosaurus). So it still does not exclude a quite large size.

I would also extend the premise of the above large paragraph to the well-known estimates in the literature, specifically Seebacher et al. (2001), Greg Paul (2016), and Molina-Perez & Larramendi (2016). These estimates tend to be among the most well-known due to being cited on Wikipedia, and subconsciously embed themselves into many's minds as the most reliable.
However, given that they are much, much smaller than the estimates outlined above (12-12.8 meters and 6000-7800 kg compared to 13-13.7 meters and 9000-9800 kg), and I am not aware of any way to get them that take into account all the above factors, my and SpinoInWonderland's estimates above are very likely the more accurate ones.

Important Sidenote: SGM-DIN 1 isn't our only giant specimen for Carcharodontosaurus. The other is a cervical vertebra (CMN 50792) that is larger than the largest estimated cervicals in SpinoInWonderland's skeletal, as was gone over here. So this specimen appears to be further support for Carcharodontosaurus reaching sizes of over 9000 kg.

Important Sidenote 2: SGM-DIN 1 (and possibly CMN 50792, we do not know its age), as per page 3 of Canale et al. (2015), doesn't seem to be an adult.

Quote:Some of the cranial elements of C. saharicus show apartial fusion between them, such as the lacrimal-prefrontal (SGM-Din 1), which sheds doubt about the full-grown condition of these materials.

For that matter, there is no reason to assume IPHG 1922 X 46 was so either. It is often said to be an adult based on fused neurocentral sutures, but as Jaime Headden points out, this really isn't a reliable proxy for whether a dinosaur is or is not an adult. We see both unfused sutures in adult animals and fused sutures in very young animals, so that really gets us nowhere.

Quote:We’ve recently begun to realize that fusion of the neurocentral suture in vertebrates is not a perfect proxy for age. In birds, all centra fuse very early in life, even before the vertebrae cease growing. In crocs, centra can remain open beyond sexual maturity. We’re finding some dinosaur skeletons presenting so-called signs of “immaturity” or lack of secondary adult characters while presenting medullary bone, suggesting they can attain sexual reproductive age before some skeletal systems finish fusion. Adulthood, then, seems complex. The Egyptian carch material is much smaller than the Moroccan material, which is nominally why it’s deem “immature.” 

Given the unreliability of the method with which IPHG 1922 X 46 was determined to be an adult, as well as the fact that we don't exactly see adults 12.5-26% smaller than subadults in other dinosaurs, there's not a single reason I can think of to assume IPHG 1922 X 46 wasn't a juvenile or subadult. So although this is not certain until more specimens are found, the fact that even the gigantic neotype doesn't seem to have been an adult most likely means Carcharodontosaurus was an extremely large theropod on average.
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Canada DinoFan83 Offline
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#7
( This post was last modified: 05-07-2021, 02:23 AM by DinoFan83 )

Carcharodontosaurus skeletal from Ibrahim et al. 2020 (about 13.5 meters).

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Carcharodontosaurus skeletal by Paul Sereno (about 13.7 meters).

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Carcharodontosaurus and Spinosaurus interactions by IllustratedMenagerie: https://www.deviantart.com/illustratedme...-842456927.

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Canada DinoFan83 Offline
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#8
( This post was last modified: 11-08-2021, 12:42 AM by DinoFan83 )

Just as in the Giganotosaurus thread, I have finally found time to add this information to WildFact.

Recently a skeletal reconstruction of Carcharodontosaurus by bricksmashtv/Gunnar Bivens has become fairly popular among the dinosaur community. And, in all fairness, I do think it is a top tier skeletal for the most part (anatomy of known parts, choice of animals to fill in gaps, etc).

However, that is not to say it doesn't have any issues, as it does appear to. Those issues being the best fit between the holotype and neotype and the resulting size estimate (12.1 meters).
More precisely, the best fit between the holotype and neotype was not replicable - and even demonstratably erroneous - on SpinoInWonderland's part.
 

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And this makes sense, considering how far a best fit of only 7% is from the listed best fits in post #6.

When correcting for this with a more replicable best fit, the size of the skeletal is increased substantially. For example, with SpinoInWonderland's best fit.
19.3%/7% (12.1 meters) = 13.5 meters

So, while Bivens has a well done skeletal, I do think its size could use some revision.
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