Moroccan vertebrae process id help Sauropod?

[jikohr]

Hi everyone!

I'm helping a friend go through a large amount of Cretaceous Moroccan stuff and came across this piece. It measures 6.3 x 6.5 x 4.33 inches (16 x 16.5 x 11 cm).

I know it's the process of a huge vertebrae, but I'm not entirely sure from what. I'm thinking sauropod but I was hoping to get a second opinion.

Any feedback is appreciated as always!

[Troodon]

Maybe these guys can shed some light

@MBL13  @LordTrilobite

[LordTrilobite]

I would say most likely a spinosaurid dorsal vertebra. Very nice piece actually.

Based on the anterior wide bases of neural arch it kinda looks like an anterior dorsal. Which would make it significant, because the neural spine is swept back. That would make it different from the Spinosaurus holotype. But it wouldn't be unheard of. There are other undescribed spinosaur anterior dorsal vertebrae from the Kem Kem beds with similar spines that do not fit the holotype from Egypt.

[jikohr]

3 hours ago, LordTrilobite said:

I would say most likely a spinosaurid dorsal vertebra. Very nice piece actually.

Based on the anterior wide bases of neural arch it kinda looks like an anterior dorsal. Which would make it significant, because the neural spine is swept back. That would make it different from the Spinosaurus holotype. But it wouldn't be unheard of. There are other undescribed spinosaur anterior dorsal vertebrae from the Kem Kem beds with similar spines that do not fit the holotype from Egypt.

Aw SWEET!!! Thanks!

By the way, what's the current deal with the whole multiple Spinosaurids in the Kem Kem thing? I found a paper that I've been reading through that claims that Sigilmassasaurus and Spinosaurus moroccanus are junior synonyms of S. aegytiacus (Sigilmassasaurus is Spinosaurus: A Reappraisal of African Spinosaurines Robert S.H. Smyth, Nizar Ibrahim, David M. Martill 2020). Basically the difference in the length of the cervical vertebrae that was used to define Sigi (you heard that nickname here first!) was individual variation between individuals which you're comment on the slight difference in the position of the neural spine, " The neural spine is swept back. That would make it different from the Spinosaurus holotype. But it wouldn't be unheard of" reminded me of their argument of intraspecific variation. Although they also pointed out that that logic would potentially include this other species from Brazil in S aegyptiacus and I guess I'm wondering how widely accepted it is that there were multiple Kem Kem Spinosaurids vs alot of agyptiacus withindividual variation in the scientific community right now.

This is another Nanotyrannus vs juvenile rex kinda thing isn't it....

[LordTrilobite]

5 minutes ago, jikohr said:

Aw SWEET!!! Thanks!

By the way, what's the current deal with the whole multiple Spinosaurids in the Kem Kem thing? I found a paper that I've been reading through that claims that Sigilmassasaurus and Spinosaurus moroccanus are junior synonyms of S. aegytiacus (Sigilmassasaurus is Spinosaurus: A Reappraisal of African Spinosaurines Robert S.H. Smyth, Nizar Ibrahim, David M. Martill 2020). Basically the difference in the length of the cervical vertebrae that was used to define Sigi (you heard that nickname here first!) was individual variation between individuals which you're comment on the slight difference in the position of the neural spine, " The neural spine is swept back. That would make it different from the Spinosaurus holotype. But it wouldn't be unheard of" reminded me of their argument of intraspecific variation. Although they also pointed out that that logic would potentially include this other species from Brazil in S aegyptiacus and I guess I'm wondering how widely accepted it is that there were multiple Kem Kem Spinosaurids vs alot of agyptiacus withindividual variation in the scientific community right now.

This is another Nanotyrannus vs juvenile rex kinda thing isn't it....

The most recent papers do indeed lump most Spinosaur material from Kem Kem into Spinosaurus aegyptiacus. But I don't think they take everything into account. And here on the forum we've seen a number of vertebrae over the years that simply do not fit with the sail of the Spinosaurus aegyptiacus holotype from Egypt.

Here are some skeletal drawings I made for reference.

 

Holotype.

 

 

 

Two different sail types from the Kem Kem beds. I think your partial vertebra neural arch fits best with this first robust spined sail.

[jikohr]

13 minutes ago, LordTrilobite said:

The most recent papers do indeed lump most Spinosaur material from Kem Kem into Spinosaurus aegyptiacus. But I don't think they take everything into account. And here on the forum we've seen a number of vertebrae over the years that simply do not fit with the sail of the Spinosaurus aegyptiacus holotype from Egypt.

Here are some skeletal drawings I made for reference.

 

Holotype.

 

 

 

Two different sail types from the Kem Kem beds. I think your partial vertebra neural arch fits best with this first robust spined sail.

Oh wow, that's really something. Kinda reminds me of all the crested hadrosaurs were it's basically the same dinosaur just with slightly different "things" sticking out of it and yet there's multiple very similar species living in the same area.

The side by side pics really put it in perspective, thanks!

[MBL13]

Classic Spinosaurine anterior (~D4) dorsal.I find no reason to refer it to other theropod,neither from Bahariya or Kem Kem.

I don't know if it's exactly Spinosaurus, we still lack comparable material and good knowledge on spinosaur neural spine variation after all.

I would say it's a spinosaur,but I cannot say much more.

It clearly does not fit the large neural arch BSPG 1912 VIII 62e from Bahariasaurus ingens.

Other taxa are quite different,such as Carcharodontosaurids and Ceratosaurs(e.g. Noasaurids,Elaphrosaurids and Abelisaurds).

Here's the Bahariasaurus specimen from Stromer(1934) in posterior view,compare it with your last image.