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anastasis008

Hello so could someone please explain the situation with sigilmassasaurus and spinosaurus was it the same dinosaur? was sigilmassasaurus bigger? 

Thanks

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Randyw

B83B975A-2C26-4A64-8FF8-4078C5A68070.jpeg

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anastasis008
1 hour ago, Randyw said:

B83B975A-2C26-4A64-8FF8-4078C5A68070.jpeg

So are the teeth from Morocco sigilmassasaurus or spinosaurus and does that mean that only sigilmassasaurus lived in Morocco at this time?

Thanks

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Randyw

Both lived in Morocco. They believe there were 5 theropods over 1 ton in Morocco at about the same time

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anastasis008
1 minute ago, Randyw said:

Both lived in Morocco. They believe there were 5 theropods over 1 ton in Morocco at about the same time

So are the teeth and fossils sold sigilmassasaurus spinosaurus or mixed ?

 

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Randyw

16886C22-0FE5-47A4-861F-242D5C811352.jpeg

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Randyw

So far they only have a few vertebrae from sigilmassasaurus have been found. No teeth. 

so the teeth are probably spinosaurus

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Randyw

I think like 4-5 neck vertebrae are all the material they have

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Randyw

I was just checking it out. They have 1 confirmed vertebrae and 15 possible but unconfirmed 

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anastasis008
1 minute ago, Randyw said:

So far they only have a few vertebrae from sigilmassasaurus have been found. No teeth. 

so the teeth are probably spinosaurus

Yes but I have a theory that both animals looked the same and so we cannot easily see the differences between small bones like teeth, another theory that I have is that there is no sigilmassasaurus to begin with they are both the same dinosaur and this has happened several times in the past.

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gigantoraptor

Spinosaurus aegyptiacus and Sigilmassasaurus brevicollis lived together in Morocco (the Kem Kem Beds). Spinosaurus maroccanus is probably the same as Sigilmassasaurus brevicollis and thus invalid. We can't distinguish teeth from the Spinosaurids so the best label for any Spinosaurid tooth that comes out of Morocco is Spinosaurid indet. 

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Randyw

Studies in 2013, 2015, and 2018 confirmed that sigilmassasaurus was a valid and indeterminate member of the family tetanurae. But things change so who knows what the future will find. More pieces are probably needed before final determination 

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Randyw
3 minutes ago, gigantoraptor said:

Spinosaurus aegyptiacus and Sigilmassasaurus brevicollis lived together in Morocco (the Kem Kem Beds). Spinosaurus maroccanus is probably the same as Sigilmassasaurus brevicollis and thus invalid. We can't distinguish teeth from the Spinosaurids so the best label for any Spinosaurid tooth that comes out of Morocco is Spinosaurid indet. 

He said it better then I could! LOL!

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Troodon

I believe the jury is still out on what and how many Spinosaurid species exist in the Kem Kem.. a growing number of paleontologists, but not all, believe Sigilmassasaurus is a valid species but beyond that is where the debate exists.  Some believe Spinosaurus aegyptiacus is only valid in Egypt and the second  Spinosaurid in the Kem Kem is indeterminate, see chart.

 

Screenshot_20170913-113556.thumb.jpg.36d1a1441bd1c70ed1bdd91cec7ebac4.jpg

 

The only known difference between Sigilmassasaurus and the other Spinosaurid is in their cervical vertebrae but beyond that its a big unknown.  Since we have not found a Sigilmassasaurus dentition/skull its assumed the morphology of their teeth is the same as Spinosaurid but it may not be.   The Kem Kem is a big unknown and views are constantly changing with new discoveries. 

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LordTrilobite
11 hours ago, gigantoraptor said:

Spinosaurus aegyptiacus and Sigilmassasaurus brevicollis lived together in Morocco (the Kem Kem Beds). Spinosaurus maroccanus is probably the same as Sigilmassasaurus brevicollis and thus invalid. We can't distinguish teeth from the Spinosaurids so the best label for any Spinosaurid tooth that comes out of Morocco is Spinosaurid indet. 

Exactly this.

The holotype of Spinosaurus maroccanus has nearly identical features to that of Sigilmassasaurus brevicollis, so yeah, it's been labeled a junior synonym.

 

 

Right now only some cervical and anterior dorsal vertebrae are known for S. brevicollis. These vertebrae can get pretty big but it's unclear as to how big the whole animal was. These vertebrae differ from Spinosaurus aegyptiacus in that all of these vertebrae have a strongly developed ventral keel running along the bottom of the centrum that ends in a triangular rugose/rough plateau. Spinosaurus aegyptiacus doesn't have this feature, though if I'm not mistaking it does have a keel on some of it's posterior cervical vertebrae.

 

Other than that feature it seems like the dorsal spines on the neck vertebrae might be a little shorter than those of Spinosaurus, but it's unclear how much of a sail Sigilmassasaurus had.

It's definitely a spinosaurid though. I think the latest studies placed it within Spinosaurini, which would make it a very close relative of Spinosaurus aegyptiacus.

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Troodon

One of the more recent papers from Lakins and Longrich looks at juvenile Sketal material and supports the argument of how much is unknown.   I think it's a bit early to be drawing conclusions on how many and what species are present in the Kem Kem other than Sigilmassasaurus.

 

Juvenile spinosaurs (Theropoda: Spinosauridae) from the middle Cretaceous of Morocco and implications for spinosaur ecology
Rebecca J. Lakin, Nicholas R. Longrich

 

 

"However, this disparity between Morphotypes A and B does not necessarily support the hypothesis that these belong to distinct species. One possibility is that they represent sexual dimorphism within a single species."

 

"Another possibility is these morphotypes represent two distinct taxa of Sigilmassasaurus, although evidence for a second Sigilmassasaurus species has never been reported from the Kem Kem. A third option is that each morphotype could represent cranial material from the only two spinosaurs known from the Kem Kem, cf.Spinosaurus aegyptiacus and Sigilmassasaurus brevicollis (Russell,1996), as suggested by Hendrickx et al. (2016). Despite this, we contend there is not sufficient evidence to assign either morpho-type to either cf. S. aegyptiacus or S. brevicollis."

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LordTrilobite

Though some Kem Kem material differs from the known Spinosaurus aegyptiacus material from Egypt, as in the Sigilmassasaurus brevicollis material, there is also material that does match very closely with the holotype of Spinosaurus aegyptiacus. I think it's still fairly safe to say that if Sigilmassasaurus is a valid genus, then we're also looking at least a second Spinosaurid that's very closely related to Spinosaurus aegyptiacus or even in the same genus and possibly species.

 

 

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Troodon

What's important for everyone to recognize is that we are still learning with new discoveries and don't be surprised if a new named spinosaurid is described.

 

Here are comments from the latest 2019 paper

(Aquatic adaptation in the skull of carnivorous dinosaurs (Theropoda:Spinosauridae) and the evolution of aquatic habits in spinosaurids: Thomas M.S. Arden , Catherine G. Klein , Samir Zouhri, Nicholas R. Longrich)

 

"This conclusion is consistent with other studies of the Kem Kem assemblage; two spinosaurids appear to be present in the Kem Kem. Evers et al. (2015) recognized two distinct vertebral morphologies, which were identified as Sigilmassasaurus brevicollis (including Spinosaurus maroccanus) and Spinosauridae indet. The second spinosaurid vertebral morph, Spinosauridae indet., tends to be smaller than Sigilmassasaurus (Evers pers. comm. to NRL, 2018) and may represent the same taxon as the Spinosaurus neotype"

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