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Spinosaurus aegyptiacus skulls. by Franoys Spinosaurus aegyptiacus skulls. by Franoys
The skulls of the enigmatic semi aquatic theropod; Spinosaurus aegyptiacus, one of the biggest predators to ever exist.

The skull was revised in depth for Ibrahim et al 2014. FSAC KK 11888, which preserves both quadrates in good conditions, most of the surangular, and part of the lacrimal in articulation with the premaxilla;  was estimated to have a skull length of 1,12 meters premaxilla to quadrate condyle. After the cross scaling of both the bombed holotype dentary and the skull remains of FSAC kk 11888, it becomes obvious that the rostrum don't fit with the skull proportions suggested at Dal Sasso et al, and the team including Dal Sasso himself proposed this new proportions for the skull, in which the rostrum is proportionally longer, as Andrea Cau has been suggesting for a while. This is the skull that was finally used for the 3D model and to reconstruct the mount, which you can see today at Berlin's museum fur narturkunde.

The result, is the referred specimen MSNM v 4047 having a skull 31,666% bigger than that of FSAC KK 11888; and 1,477 meters premaxilla to quadrate, the universal measurement used to compare the length of theropod skulls from different species. As in a big number of other theropod species, other metrics are considerably longer. As a consequence, the most likely result is for MSNM v 4047 to have a body length of about 15 meters in length, rather than the 17 meters that were proposed in Dal Sasso et al (2005)

MNHN SAM 124 is a partial rostrum, very similar to MSNM v 4047, that was referred to the species Spinosaurus marrocanus, but Ibrahim et al 2014 and Hendickx et al 2016 consider this skull as belonging to Spinosaurus aegyptiacus, and as such was included in the chart.
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:iconyty2000:
yty2000 Featured By Owner Jan 24, 2017
Didn't Ibrahim lump every spinosaurine from north Africa into S. aegypriacus?
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:iconfranoys:
Franoys Featured By Owner Edited Jan 28, 2017
Yes. The team working at Ibrahim et al lumped the holotypes of S.marrocanus and Sigilmassasaurus into S aegyptiacus, which resulted of the lumping of the species. Both Sigilmassasaurus and Spinosaurus marrocanus (Russel 1996) holotypes are presacral vertebrae, which they considered to be identical, and also similar enough to the cervicals/anterior dorsals preserved in Spinosaurus C (FSAC kk 11888). Later on as you surely know Evers et al recovered Sigilmassasaurus and proposed the existance of a second Spinosaurine taxon in north Africa, with S. marrocanus still being invalid and lumped into Sigilmassasaurus, instead of Spinosaurus. S marrocanus has been proposed to be nomen dubium several times, for example in Sereno 1998 and Dal Sasso 2005, and every paper afterwards lumps it's remains in either Spinosaurus (Ibrahim 2014) or Sigilmassasaurus (Evers 2015)

However, if this comment is because of the inclusion of the rostrum referred to S.marrocanus, keep in mind it is not the holotype of marrocanus, just a remain incorrectly referred to it, with very little basis. The range of S.aegyptiacus could have reached the location in which the rostrum was found if FSAC kk 11888 is anything to go by.  And based on comparisos with material referred to Spinosaurus ( MSNM v 4047) and if you asume  MSNM v 4047 to be Spinosaurus, there is no reason to split MNHN SAM 124 from it, that's why Hendrickx et al 2016 considers it to be Spinosaurus aegyptiacus instead of marrocanus (or a Spinosaurid different to Aegyptiacus), despite their work further reinforcing the pressence of a second Spinosaurine taxon in north Africa.

Citing Hendrickx et al (2016): 

The morphology of the fused premaxillae and maxillae referred to Smaroccanus are extremely similar to those ascribed to Saegyptiacus, and the main difference lies in the premaxillary tooth count (Fig 11). In Smaroccanus, each premaxilla bears seven alveoli whereas the premaxilla of the specimen MSNM V4047 referred to Saegyptiacus, only has 6 teeth. This difference is, however, negligible given the fact that tooth count can vary during ontogeny in some basal tetanurans (e.g., [98,99]), between individuals of the same species (e.g., [100103]), and even between left and right premaxillae of a same specimen 
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:iconthedinorocker:
thedinorocker Featured By Owner Jan 23, 2017
A bird told me you're really work on Spinosaurus...
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:icongrisador:
grisador Featured By Owner Jan 10, 2017
That guy was definetly big :o
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:iconpeteridish:
PeteriDish Featured By Owner Dec 22, 2016  Hobbyist Photographer
now that is a real chomper! :D
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:iconspinosaurus14:
Spinosaurus14 Featured By Owner Dec 18, 2016
As usually, good work, but is there a reason to portray the skull as 1,58m, which is smaller than the skull reconstructed by Ibrahim?
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:iconfranoys:
Franoys Featured By Owner Edited Dec 18, 2016
No, it is not smaller, it is the same exact size. I used to believe it was longer but it isn't. The skull follows their reconstruction to the milimeter. I did some small tweaks to the depth to better fit some of the fragments described into the composite and of course scaled the fragments and drew the bones but it is mostly their own model. The newer reconstruction of the skull is much more compact than the older one (see the description).

And thank you!
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:iconthedinorocker:
thedinorocker Featured By Owner Dec 18, 2016
Good chart...
Are you working on Spinosaurus skeletal?
I ask because I work a lot on it and I am pretty confident with Ibrahim measurament of Neotype material
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:iconfranoys:
Franoys Featured By Owner Edited Dec 18, 2016
For the most part, me too. I don't think they will turn out to be massively wrong and of course the 27,7% bigger hindlimbs was suggested by some authors due to a missinterpretation (which was also fault of those who wrote the SM because they didn't specify the landmarks used to measure the vertebrae).

About the skeletal, we will see. Perhaps...
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