Differences between teeth of Spinosaurus aegyptiacus

[LauraMedea]

Hello everyone, I have a question to ask the experts on the forum regarding the teeth of the Spinosaurus.

I was wondering what caused the presence or lack of the common vertical grooves on the crown of the tooth.

I have seen that some teeth, described by the sellers as natural and having intact enamel,  have these grooves very marked, in others they are practically absent (e.g. pics below). Does this depend on the state of preservation, the age of the animal, the position of the tooth within the mouth or what?Thanks to anyone who can give me the infos

[Kikokuryu]

Smooth crown versus striated/ridged crown is likely just a difference in genus or species. As of right now, we don't know if the teeth of Kem Kem cf. Spinosaurus aegyptiacus (Spinosaurus maroccanus), Sigilmassasaurus brevicosis, and possibly a third species can be distinguished or not. A similar situations with Carcharodontosaurus and Sauroniops.

 

If we look at what was described in the original Stromer's Spinosaurus aegyptiacus from the Bahariya Formation. We see that it is described as having enamel that usually smooth, and only ridged/wrinkled at the base under magnification. This would suggest that the heavily ridged morphology may not belong to an animal closely related to the original Spinosaurus.

 

The big problem then comes, did paleontologists make a mistake in assigning the wrong animal as the neotype of Spinosaurus in Morocco if those heavily ridged ones are now assigned to Spinosaurus. I recall the ridges of Ichthyovenator and Siamosaurus have sometimes been compared to those of Spinosaurus, but I assume those referred to the Moroccan material.

 

I think if you want a tooth that is as close to the original, you would go with the smooth crown morphologies.

 

And if we look at what was available with the original holotype, there's quite a bit of tooth material. So it's possibly also not just a matter of, well, the few tooth positions they had only gave a limited view of their morphs. I think it's safe to assume smooth crown was the norm for the species of Egypt.

Edited August 19 by Kikokuryu

[LauraMedea]

2 hours ago, Kikokuryu said:

Smooth crown versus striated/ridged crown is likely just a difference in genus or species. As of right now, we don't know if the teeth of Kem Kem cf. Spinosaurus aegyptiacus (Spinosaurus maroccanus), Sigilmassasaurus brevicosis, and possibly a third species can be distinguished or not. A similar situations with Carcharodontosaurus and Sauroniops.

 

If we look at what was described in the original Stromer's Spinosaurus aegyptiacus from the Bahariya Formation. We see that it is described as having enamel that usually smooth, and only ridged/wrinkled at the base under magnification. This would suggest that the heavily ridged morphology may not belong to an animal closely related to the original Spinosaurus.

 

The big problem then comes, did paleontologists make a mistake in assigning the wrong animal as the neotype of Spinosaurus in Morocco if those heavily ridged ones are now assigned to Spinosaurus. I recall the ridges of Ichthyovenator and Siamosaurus have sometimes been compared to those of Spinosaurus, but I assume those referred to the Moroccan material.

 

I think if you want a tooth that is as close to the original, you would go with the smooth crown morphologies.

 

And if we look at what was available with the original holotype, there's quite a bit of tooth material. So it's possibly also not just a matter of, well, the few tooth positions they had only gave a limited view of their morphs. I think it's safe to assume smooth crown was the norm for the species of Egypt.

Thanks so much for the explanation. This is all very interesting. In fact, for both types the tooth is always classified as Spinosaurus aegyptiacus, which is why I had doubts about it. This is a big gap that perhaps will be resolved and officially clarified over time. In the meantime, thank you for giving me these informations. It will mean that if I ever purchase a Spinosaurus tooth for my collection with clearly visible ridged surface till up to the tip, I will mark Spinosaurus sp. on the tag. while for the tooth with the smooth crown I can be confident in identifying it as S.aegyptiacus.