Is this a Baby Mosasaur or some other species

[Biotalker]

I acquired this fascinating fossil at the recent show. My first reptile bones. The dealer said it is from Morocco and of the same age (and matrix) as the mosasaur jaw sets he had next to it. But he wasn’t sure if it was a baby mosasaur or a different species of smaller aquatic reptile. I’m pretty sure TFF can answer these questions I have.

1) Is this a baby mosasaur or a different species (if so what species)?

2) Can you identify the visible bones?

3) Is it worth it or feasible to attempt to reveal more of this fossil?

4) If so, what special procedures/tools would be necessary to prep this fossil to reveal more skull?

[Gareth_]

@pachy-pleuro-whatnot-odon This has got to be one for you

[Rockwood]

First step; scrutinize the matrix by probing with a heated tip to be sure it's real. As opposed to a mixture of auto body filler (bondo) and dust.

[pachy-pleuro-whatnot-odon]

I'll have to come back with a more detailed answer later, but this is indeed mosasaur, which you can tell by the shadow if the skull bones. Going by the teeth, it's a specimen of Halisaurus arambourgi, a rather small-sized mosasaur - the smallest, in fact, currently known from the fauna found in the Maastrichtian phosphates of Morocco. It is certainly possible that there may be some more bone material stuck in the matrix, but I wouldn't count on finding too much. With the Moroccan pieces it's typically what-you-see-is-what-you-get, with the possible exception of some superfluous fish bone.

 

3 hours ago, Rockwood said:

First step; scrutinize the matrix by probing with a heated tip to be sure it's real. As opposed to a mixture of auto body filler (bondo) and dust.

 

Looks real enough to me (at a quick glance), anatomically correct too. But since some bone mite rather far apart, it could be that some of them have been placed in the matrix.

 

@Praefectus @LordTrilobite

Edited August 26, 2021 by pachy-pleuro-whatnot-odon

[LordTrilobite]

I'm seeing maybe 50% of a complete skull here. I agree that this is Halisaurus arambourgi.

Much of the forehead is complete. I'm seeing the premaxilla, left maxilla, right dentary and also one side of the back of the jaw as well as some scraps of the braincase area.

Everything here looks real based on just these photos. No red flags that I can see.

[snolly50]

31 minutes ago, pachy-pleuro-whatnot-odon said:

 Halisaurus arambourgi,

 

Yes, this appears a well applied ID.

 

31 minutes ago, pachy-pleuro-whatnot-odon said:

wouldn't count on finding too much.

 

With a goal of improving the display appeal of the piece, it seems that little will be revealed that is at least not already mostly visible. However, with small effort and simple tools the aesthetics of the piece might be improved. Below is a link to a brief exposition on akin material. If the matrix is as I suspect, its granular nature will make for a relatively easy "clean-up." Good luck, have fun.  

 

 

[Praefectus]

+1 for Halisaurus arambourgi. 

 

I'm seeing a frontal and right maxilla in what is exposed. Probably more under the matrix. 

[pachy-pleuro-whatnot-odon]

I agree with the analyses given above as to the skull elements present. We're looking at the inside of the skull from below, the ventral side. The bit of jaw towards the bottom of the block therefore corresponds to the left maxilla, whereas the jaw-section at the top exhibits the typical morphology of a dentary and can thus be identified as part of the right mandible. The single tooth next to the bit of bone directly underneath the dentary seems to suggest the bone corresponds to the premaxilla, another element of the snout. The "rocket"-shaped bone central to the block consists of the frontal and prefrontal, whereas it is overlain by what might be part of pterygoid bones. Various other bits and pieces are strewn around...

 

As we're looking at the skull from the vertebral side, it's unlikely they'll be more bone to be found in the matrix, although a bit of additional prep-work may makes those bones present more visible. As @snolly50 suggested simple tools suffice for this: just some dentists' tools and may be a sharp knife. The matrix, though covered in white glue to consolidate the specimen and therefore feeling quite hard to the touch, is actually quite soft and can be softened even further by applying water (either by inundation or using a plant spray). Similarly, the glue can be removed using either water or acetone (take care when working with acetone however as the substance is toxic and its fumes are highly inflamable) if needed, but keep in mind that this does weaken the fossils and that subsequent application of another consolidant is recommended (cleaning off the old glue can help reveal the bright white colour of the bone underneath; replacement can be found in products like Paraloid B72 or an acrylic crafts seal). I personally don't use water when prepping bones out off these blocks, as I don't think it's necessary, and believe it generally weakens the bones as well, as they would also absorb some of the water. In the end, though, you'll need to find what works best for you...

[Biotalker]

On 8/26/2021 at 8:12 AM, snolly50 said:

with small effort and simple tools the aesthetics of the piece might be improved. Below is a link to a brief exposition on akin material. If the matrix is as I suspect, its granular nature will make for a relatively easy "clean-up." Good luck, have fun. 

Thank you for that jolly snolly adventure back to your Halisaurus prep of four years ago. That is a fun thread to read! Duly inspired for at least a clean up of my mosasaur skull parts this winter (secretIy, I would love to get a sense of the brain case within this skull, though perhaps unlikely it will be revealed).

Michael