Moroccan Spinosaurids

[MBL13]

Hello, I'm new to this forum.

In the last months I have been involved in a project regarding North Africa spinosaurids.Because of the reduced data I have, I want to know if anyone could share photos of their specimens.Most of the specimens I need are presacral vertebrae and posterior cranial bones(including,if possible,a braincase). Also, any information in favour of a second morphotype could be really helpful;even though I have already treated this point, I want different opinions on this topic.

Thanks a lot in advance to anyone.

[Top Trilo]

This thread may help

 

[LordTrilobite]

I got a bunch of stuff.

 

I have a bunch of vertebral material, both presacral and caudal. Also a partial braincase. I scan a lot of the fossils I have, including my spinosaur material.

You can find all my spinosaur 3d scans here:
https://sketchfab.com/lordtrilobite/collections/fossil-scans-spinosaurs

This includes a few sacral verts and some dorsal.

 

Spinosaur braincase.

 

 

 

And I do think there seem to be two morphotypes present. The two types of frontal bones seem to be pretty different. One type with low brows, and one with higher brows that would set the eyes at a higher position. I also have a dorsal vertebra centrum with a pronounced keel and rugose plateau that's consistent with Sigilmassasaurus brevicollis, but not with Spinosaurus aegyptiacus. I don't have any good photos of it at the moment though.
 

[MBL13]

Thanks a lot for the braincase,first one I've seen complete, compared to other material from Suchomimus,Baryonyx and Irritator it seems to be similar overall (I'm yet to be familiarised with its anatomy);a complete lateral view could be also useful to compare with some skull reconstructions presented.

Well, I'm yet doubting on the specimens described by Arden et al (2018),it's next on my list,however on the dorsal axis I've detected a few interesting details that help with isolated elements placement:

There seem to be an interemediate morphotype(between Sigilmassasaurus and Spinosaurus) in D4:Moderate keel, slightly wider centrum 1.25/1,laterally placed and elevated parapophyses, accompanied with an elongation and constriction of the centrum,also note the developed hyposphene. More posterior vertebrae (D5-6) have anteroventral processes (intermediate keels) with elongated and pinched centrums,raised parapophyses and facet ratio is around 1/1 for this morphotype. In contrast D7 have very weak processes,more like ridges,very elongated centrums and are extremely transversely compressed at the mid length. Next we have the aegyptiacus morphotype,with variable proportions of the centrums,yet they are clearly distinct by the following: Very tall anterior facets1/ ≥1.15, parapophyses on the anterior spinodiapophyseal lamina and slightly displaced posteriorly.They're elongated and transversely compressed, specially when comparing width/length, these vertebrae have a 1/2(except element "h ", which is a posterior dorsal,in proximity to the sacrum),the other morphotypes (except D7) have a 1/ ~1.6 ratios. So the only specimen that doesn't perfectly fit is element"h" however it still cannot be considered as a D4-7 because of an exceedingly tall centrum,no parapophyses below the suture,and anterior facet taller (1/1.13) than wide,so I concluded that it's just a posterior dorsal. On the other hand, element "I" fits as an intermediate between D7 and D9 in various aspects,so I suspect it's actually a D8, instead of D13 as usually considered. 

To infer significant variation I used Baryonyx to see how vertebrae change in the axial line and found very similar results,yet not as extreme. And also,based on some images of FSAC-KK-11888,it's anteriormost dorsal centrum might have a moderate process or keel in ventral view,might be taphonomic also. 

Nevertheless I have found some vertebrae which show a weakly developed ventroposterior pedestal or platform,yet this occurs almost in small ≤150 mm specimens. I think it's related to ontogeny,with one sex reaching an adult stage at smaller size,thus comparing similar sized specimens might be troublesome. This is based on comparisons between cervical (C9) and cervicodorsal (D1-2) vertebrae,as we have various specimens of different size. This shows the development of the platform and keel (between CMN 41774 and CMN 41856). The first one is 67 mm long,with a smooth keel and almost absent vpt(ventral platform),while the last one is 146 mm,with a strong keel and well developed platform. On dorsal centra,the opposed seems to happen,with small specimens having more,but not deeper, rugosities and sometimes and elevated isosceles triangular surface(especially on D4). On the other hand,D5 and D6 have thinner,more pointed keels,which become wider and lower, meeting the centrum surface uniformly. 

For the mentioned dorsal centrum,does it resemble this condition?

 

Most of those vertebrae have been illustrated and described by Russell (1996) and McFeeters et al (2013). Sadly I still require additional specimens, specially bigger ones(over 250 mm) to understand some potential changes.

I could try to elaborate more on the topic but it's still in development,so I need to recheck some interpretations and new specimens to see if it holds up.

It's also noteworthy that the distinct morphotype,with strong keels and platforms(except C7)are the smallest actually (between 8.5-10 m),as they're clearly smaller than the neotype and holotype,we shouldn't use size as a proxy to infer taxonomy. And because of the "strong" condition, we could considered them to be closer to skeletal maturity. 

Edited January 2, 2021 by MBL13

[LordTrilobite]

No that anterior dorsal you're showing looks nothing like the one I have. Mine looks to be a posterior dorsal. It has a very pronounced keel and the rugose plateau can be clearly seen too. It's not as strongly opisthocoelous as the anterior dorsal vertebrae.

I have it stored somewhere but this is the only photo of it I have at the moment. This was before prepping. This is the right side view.

 

And side view of the braincase. It's slightly anteroposteriorly crushed tho. In anatomy it's closest to that of Irritator. The braincases of Baryonyx and Suchomimus are more robust.

[MBL13]

The dorsal centrum seems very interesting, however,as you mentioned, it doesn't match exactly the typical condition seen on dorsal vertebrae, which normally have only keels and sometimes an elevated surface. Because of the poorly opisthocelous nature of the centrum,and absence of parapophyses,it might be a mid-posterior dorsal, however I still need to know the size,and both anterior width and height to be sure. And also note that for example, the D3 NHMUK PV R 16435 (Evers et al. 2015,see fig.13) and D4 BSPG 2013 I 95(Evers et al. 2015,see fig.14); have smooth keels and underdeveloped platforms, which is quite distinct,at least in lateral view,to your centrum. This specimen might be associated with a new morphotype,not yet recognised;or maybe "Sigilmassasaurus" includes two, unrecognised distinct species.

Thanks for the lateral view of the braincase,and by the way,it's the only one you know,or has any other specimen been reported recently?

Note: Exchanged the names of the laminae on the last comment,it should be the anterior centrodiapophyseal lamina,not the spinodiapophyseal.

Edited January 2, 2021 by MBL13

[LordTrilobite]

That keeled dorsal centrum is around 8 or 9 cm. And I think someone else on the forum had a partial basisphenoid that's twice the size of my specimen. Mine is rather small. Around the size of that of Irritator. The only other examples I know of are from composite skulls that are known from photos on the internet.

There's this skull that seems to show at least some part of the braincase. But it's a composite and some parts are reconstructed in a weird way. The braincase area also doesn't seem to match the jugal and rostrum very well.

[MBL13]

Really interesting,a basisphenoid two times bigger should have come from a large adult,I'll search for that particular specimen, specially to see any allometry-dependant variables. And also,any changes in ecology, compared with other spinosaurids,might be present in some cases,so it should help a lot.

So the centrum is quite small, at least 1/2 the size of subadult/young adults of Spinosaurus aegyptiacus. One thing that comes to my mind is that,while large theropods get a lot of attention,there might be some small-sized species yet to be found;as it happens with some small (≤2m) specimens,with possible noasaurid affinities. Other possibility is that it comes from a young individual,however I think this as unlikely,from the image,both keel and platform are quite pronounced,a condition only seen in large specimens.An heterochromic pattern for the vertebrae could be possible, nevertheless I don't have enough data to be sure.

Sure the skull is badly arranged,I suppose that at least two-three specimens are mixed,I've seen similar ones partially reconstructed. I think it was primarily reconstructed to have some kind of "appealing",but in terms of anatomy it seems really off.

[LordTrilobite]

Here's a photo of that partial basisphenoid when it was being sold on the internet. Top middle.

[MBL13]

So this one, right?

And also,it should be my last question,I've found in this forum a very interesting specimen:

I think this is either the posteriormost dorsal vertebrae,or a mid sacral one(I'm inclined towards the later). It matches the size and the neural spine morphology of the sacral vertebrae from BSPG 1912 VIII 19 (Stromer,1915;see plate 1),albeit it's slightly more caudally displaced. Compared with dorsal neural arches,the laminae are less distinguishable(even absent?),and the transverse process are first anteposteriorlly compressed and then widened, forming a "teardrop".In ventral view it has a strange " webbing " connecting the process and both facets. The specimen seems to have flat facets(indicative of a posterior position),and has a pronounced posteroventral lip,with a wide posterior facet. Do you have any additional information,or specimens, about this morphotype?

 

Edited January 2, 2021 by MBL13

[Troodon]

On 1/2/2021 at 7:50 AM, MBL13 said:

So this one, right?

And also,it should be my last question,I've found in this forum a very interesting specimen:

I think this is either the posteriormost dorsal vertebrae,or a mid sacral one(I'm inclined towards the later). It matches the size and the neural spine morphology of the sacral vertebrae from BSPG 1912 VIII 19 (Stromer,1915;see plate 1),albeit it's slightly more caudally displaced. Compared with dorsal neural arches,the laminae are less distinguishable(even absent?),and the transverse process are first anteposteriorlly compressed and then widened, forming a "teardrop".In ventral view it has a strange " webbing " connecting the process and both facets. The specimen seems to have flat facets(indicative of a posterior position),and has a pronounced posteroventral lip,with a wide posterior facet. Do you have any additional information,or specimens, about this morphotype?

 

 

I just saw this post and I'm the one holding the spine since it was broken.   This was at the 2020 Tucson show.    I tried to purchase it but it already been sold and I do not know the buyer.   Here are a couple of additional photos.