Yet another Mosasaur jaw

[snolly50]

Here is another jaw. It is offered as Halisaurus  and is reportedly from Oued Zem of Morocco. It is 10.2" in length.

 

Jaws are a common inquiry here and several members are frequently kind enough to give their experienced opinion of the posted fossils. I would find it interesting and perhaps instructive to the general Forum; if experienced respondents would provide as much detail as they can as to how they formulate their opinion (e.g. common responses such as "teeth may be added," "matrix is not original, etc.") The question I am posing is how are these opinions reached? What clues are utilized?  The following photos are the sellers. I realize that any conclusions reached in this section of the Forum are impacted by the quality and completeness of the provided images. Please respond to this fossil with as much "detective" detail as you care to provide. Thanks.

 

 

 

[Manticocerasman]

the difference of color and structure ( very smooth and almost pink ) between the teeth and the jaws are a good indicator that the teeth were added.

[snolly50]

I am adding cropped images of the teeth, as these are usually a prime area to be scrutinized. Unfortunately, the resolution of the crops is obviously reduced. It is hoped they are helpful nonetheless.

 

 

 

 

[snolly50]

1 hour ago, Manticocerasman said:

between the teeth and the jaws

Thank you for the observation. I assume you mean between the crown and the root, where some of the teeth seem to display a whitish colored band?

[Manticocerasman]

6 minutes ago, snolly50 said:

Thank you for the observation. I assume you mean between the crown and the root, where some of the teeth seem to display a whitish colored band?

yes indeed, I've marked them on this picture:

[LordTrilobite]

Yeah, at least some of the teeth have been added.

[snolly50]

1 hour ago, Manticocerasman said:

marked them

Thanks for the additional comment. So, you are suspicious of not just a narrow seam, as expected if a loose crow was glued to an existing root; but of the area of the root from crown base to insertion point of the jaw?

 

1 hour ago, LordTrilobite said:

teeth have been added.

Thank you! Do you judge the tooth pictured below to be a natural tooth? It is one of the clearer close-up images. Also, please point out one that you identify as typical of the appearance of added teeth. I wish the photos were higher resolution, it would make for a more instructive post to be able to clearly see the red flag indicators.

Again thanks to all those who respond with their opinions.

 

[LordTrilobite]

33 minutes ago, snolly50 said:

Thank you! Do you judge the tooth pictured below to be a natural tooth? It is one of the clearer close-up images. Also, please point out one that you identify as typical of the appearance of added teeth. I wish the photos were higher resolution, it would make for a more instructive post to be able to clearly see the red flag indicators.

Again thanks to all those who respond with their opinions.

Yes I would say that tooth has been added. My previous answer was very brief, so I'll give a more in depth analysis here.

 

The photos are barely adequate but yeah that particular closeup is just detailed enough to tell me that this tooth at least has been added.
If I would have to hazard a guess I would say that all the teeth are added in except for the tooth on the left floating outside the jaw bone. The other teeth have a different colour and the joins between de crowns and roots look kinda suspect.

So anyway, what gives this tooth in the above photo away is that the join between the crown and root looks too homogeneous and the wrong colour. It also looks to be slightly too tall, raising up the crown too much. The surface of the join looks a bit grainy and it lacks the vertical striations I'd expect from an original. Notice the colour of this whole area seems to be the same dull beige colour. It's similar to the bone below it. But the beige colour on the bone is really just remnant of dirt from the matrix. The actual colour of the bone can be seen at the bottom. It's an off white. While I'd expect some beige between the crown and root, some areas should be fairly smooth. Especially right below the crown. And smooth areas hold dirt less. So I would expect some white peaking in here and there. As I said before, I think the one floating tooth might be original. Notice that it has more white in various places around the base of the crown.

There is also the matrix around the teeth that make most of them look suspect. Teeth that are added in often have a kind of moat around them, since holes had to have been dug out of the matrix to later insert new teeth. Most of the time if you see a bone directly beside a tooth crown, chances are that the tooth is original. But here we see most of the teeth do have some dug out areas around them. The various bone fragments in the matrix block also seem to stop near the teeth. So that's very suspicious.

 

Here is an example of original teeth from my collection. Note that the one side in the first photo kinda looks a bit weird and almost suspicious even though there's absolutely no tampering here. This is because there's still a little bit of matrix left in the groove where the root starts. But on the other side we can clearly see that the whole of the crowns and roots smoothly transition from crown to root. The length of this area can vary. As you can see the tooth on the left has a bit of a taller middle area. The colour on these is somewhat homogeneous but there are a number of imperfections and cracks running along it. It's also pretty typical to see the cracks running horizontally. And note the vertical striations of the root meeting the crown which I mentioned were missing on the teeth you posted.

[snolly50]

@LordTrilobite Excellent! thank you for the detailed observations regarding the appearance of an original tooth. I think your explanation (and photos) will be helpful to myself and other Forum members as we face this frequently occurring puzzle.