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Two more interesting micro teeth from the Mesaverde


fossilsonwheels

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That little vial of micros from the Mesaverde formation is the gift that keeps on giving. I dissolved some of small bits of matrix in vinegar. Still no batoid teeth but a couple of shark teeth did emerge. 

 

Mesaverde Formation, Rollins Member

Colorado

 

The first is a candidate for the smallest shark tooth in my collection. At most it is 1mm and I think it is another possible Cat Shark tooth. Quite similar to some NJ teeth I found on line. I am open to other possibilities as far as an ID goes. Regardless, it is one very cool looking micro tooth

8542F75F-E799-401F-A4E2-E00BD57DBE37.jpeg

F53A863E-5EAA-474F-B169-165DFF4C2762.jpeg

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So this is an interesting one and I will not even speculate on an ID. 4-5mm and with an interesting root structure even though much of it seems to be missing. It appears to have had quite a nutrient groove. I will take photos of the other side and from different angles. 

 

I really have no clue but it is pretty interesting I think. 

B57F4781-304E-4B99-BAB1-E9C0DB8E8D70.jpeg

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The second elongated one may have most of the root broken off but it may also be a symphyseal tooth (from the centerline of the jaw where the left and right halves join). Many shark species have very different shaped teeth in this region--elongated, twisted, smaller. the symphyseal teeth from the snaggletooth species Hemipristis serra that are reasonably common in Florida fossil sites have small, almost two dimensionally narrow symphyseals that end up in my micro-matrix because of their size. Always fun to come across one of those.

 

I can't tell if the first tooth pictured (with the side cusps) might be something in the catshark family or is more likely to be some species of sand tiger shark (though at 1 mm catshark is a good possibility). If sand tiger teeth are common in this matrix, then possibly the long skinny tooth may be a sand tiger symphyseal. Not stating anything for the record (the matrix you are searching is out of my bailiwick) but suggesting ideas for possible research into their identities.

 

 

Cheers.

 

-Ken

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12 minutes ago, digit said:

The second elongated one may have most of the root broken off but it may also be a symphyseal tooth (from the centerline of the jaw where the left and right halves join). Many shark species have very different shaped teeth in this region--elongated, twisted, smaller. the symphyseal teeth from the snaggletooth species Hemipristis serra that are reasonably common in Florida fossil sites have small, almost two dimensionally narrow symphyseals that end up in my micro-matrix because of their size. Always fun to come across one of those.

 

I can't tell if the first tooth pictured (with the side cusps) might be something in the catshark family or is more likely to be some species of sand tiger shark (though at 1 mm catshark is a good possibility). If sand tiger teeth are common in this matrix, then possibly the long skinny tooth may be a sand tiger symphyseal. Not stating anything for the record (the matrix you are searching is out of my bailiwick) but suggesting ideas for possible research into their identities.

 

 

Cheers.

 

-Ken

Hi Ken

 

The first tooth may not even 1mm. It is really tiny. Possibly smaller than the Chiloscyllium I have. Likely the smallest in my collection. For that reason I think a Cat may be more likely but it could be a Sand Tiger. 

 

So many of the larger teeth were partials so I had difficulties identifying them but Sand Tiger was what I thought several of them were so I would think they are common in the formation. I will look into symphyseal teeth for sure. I appreciate the suggestions very much !

 

Kurt

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I too thought of cat shark for the top one

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'Those who cannot remember the past are condemned to repeat it.'

George Santayana

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41 minutes ago, hemipristis said:

I too thought of cat shark for the top one

I just can not see a Sand Tiger tooth being THAT small.  Thank you

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Indeed! Sharks do start out small but there has to be a lower limit to the size of the teeth that they are born with. I brief check online for the Mesaverde Formation turned up a thesis paper mentioning the larger species of Cretaceous sharks found in that formation which listed the goblin shark Scapanorhynchus as being present so that may possibly be a lead for the second tooth. I have exceedingly little experience with Cretaceous shark teeth (only having visited Green Mill Run in NC once so there are many others here with infinitely more experience with teeth of this age. @sixgill pete @Al Dente

 

If you can relocate the first little mystery tooth and toss it back up on the scope, it might be informative to see the reverse (labial) side of that tooth. I'm assuming that face may show some plications (wrinkles) at the base of the enamel.

 

 

Cheers.

 

-Ken

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4 hours ago, digit said:

Indeed! Sharks do start out small but there has to be a lower limit to the size of the teeth that they are born with. I brief check online for the Mesaverde Formation turned up a thesis paper mentioning the larger species of Cretaceous sharks found in that formation which listed the goblin shark Scapanorhynchus as being present so that may possibly be a lead for the second tooth. I have exceedingly little experience with Cretaceous shark teeth (only having visited Green Mill Run in NC once so there are many others here with infinitely more experience with teeth of this age. @sixgill pete @Al Dente

 

If you can relocate the first little mystery tooth and toss it back up on the scope, it might be informative to see the reverse (labial) side of that tooth. I'm assuming that face may show some plications (wrinkles) at the base of the enamel.

 

 

Cheers.

 

-Ken

Ken

 

I am going to take some additional photos of both teeth today. I was looking at symphyseal teeth yesterday and I did see a publication on the teeth of Scapanorhynchus texanus from the Eutaw formation that did include a symphyseal tooth.

Mitsukurinid-shark-teeth-Scapanorhynchus-texanus-from-the-Eutaw-Formation-at-Luxapalila.png

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  • 1 month later...

Hi Kurt,

 

I agree that the first tooth is a cat shark and perhaps undocumented.

 

I've looked at the second tooth several times.  At first I thought it was a cat shark though 4-5 mm seems unusually large for that.  However, I have a Protoscyliorhinus tooth from the Early Cretaceous of France that's about 3mm. 

 

At 4-5 mm your tooth seems too small for a Scapanorhynchus (lower) symphyseal because teeth at that position, while smaller than the first anterior, they are not as small and reduced in morphology relative to the symphyseals of other genera.  In fact, Jim Bourdon (elasmo.com) considers this tooth an anterior tooth rather than a true symphyseal because it was in place within the anterior hollow (as a tooth of similar shape is in the jaws of the related Mitsukurina) rather than on or close to the symphysis.  However, like a symphyseal, this tooth might not always present in the jaws - perhaps in the process of becoming vestigial-absent.  It's a rare find as a fossil perhaps because it is a little more fragile (a more slender tooth that can't take too much water wear) and it might not have been present in all individuals.  It's hard to say with extinct forms because that tooth position could be rare just because the teeth are more fragile.

 

Given that the root is incomplete so the original tooth was likely at least a millimeter larger, I would say that it is that lower symphyseal (Bourdon's A0) of Scapanorhynchus.

 

Jess

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3 hours ago, siteseer said:

Hi Kurt,

 

I agree that the first tooth is a cat shark and perhaps undocumented.

 

I've looked at the second tooth several times.  At first I thought it was a cat shark though 4-5 mm seems unusually large for that.  However, I have a Protoscyliorhinus tooth from the Early Cretaceous of France that's about 3mm. 

 

At 4-5 mm your tooth seems too small for a Scapanorhynchus (lower) symphyseal because teeth at that position, while smaller than the first anterior, they are not as small and reduced in morphology relative to the symphyseals of other genera.  In fact, Jim Bourdon (elasmo.com) considers this tooth an anterior tooth rather than a true symphyseal because it was in place within the anterior hollow (as a tooth of similar shape is in the jaws of the related Mitsukurina) rather than on or close to the symphysis.  However, like a symphyseal, this tooth might not always present in the jaws - perhaps in the process of becoming vestigial-absent.  It's a rare find as a fossil perhaps because it is a little more fragile (a more slender tooth that can't take too much water wear) and it might not have been present in all individuals.  It's hard to say with extinct forms because that tooth position could be rare just because the teeth are more fragile.

 

Given that the root is incomplete so the original tooth was likely at least a millimeter larger, I would say that it is that lower symphyseal (Bourdon's A0) of Scapanorhynchus.

 

Jess

Hi Jess 

 

I sure appreciate your input as always. I am satisfied with Cat Shark on the first one and possibly undocumented sure has a cool ring to it lol 

 

Your opinion on the second one confirms what I came up with so I’m more than happy to agree. I didn’t find many examples of Scapanorhynchus symphyseals when I researched it so I would agree they seem fairly rare. I ended up finding some really cool stuff in this matrix. Several Cat Shark teeth, the Chiloscyllium and the Goblin. I can not wait to find some more Cretaceous micro mix to go through. 

 

Thanks again 

 

kurt

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