Ray or shark denticle

[old bones]

Here is another unusual find from the Cookie Cutter matrix. Years ago I found a similar on from a different location. Is it possible to narrow this down to shark or ray?

[GeschWhat]

Cool find. 

[old bones]

On 4/19/2020 at 9:46 PM, GeschWhat said:

Cool find. 

Thanks, Lori

[siteseer]

I'm not sure but It does look like a dermal denticle.  The last time I saw one like that it was identified as coming from the tip of the snout of a shark.  Marco Sr. has looked at a lot of dermal denticles.  Maybe he can take a look.  Marcel needs something to do too.

 

@MarcoSr  @isurus90064

 

[Troodon]

Agree looks like a shark denticle

https://www.researchgate.net/publication/311957637_Dermal_denticles_as_a_tool_to_reconstruct_shark_communities

 

 

[MarcoSr]

10 hours ago, siteseer said:

I'm not sure but It does look like a dermal denticle.  The last time I saw one like that it was identified as coming from the tip of the snout of a shark.  Marco Sr. has looked at a lot of dermal denticles.  Maybe he can take a look.  Marcel needs something to do too.

 

@MarcoSr  @isurus90064

 

 

I feel that the specimen is a ray dermal denticle based upon size and specimen features.  The vast majority of shark placoid scales (some researchers use the term dermal denticles) are less than 1 mm in size.  However,  there are some species of shark like Brambles that can have much larger dermal denticles and Brambles can also have fused dermal plates up to 25 mm.  The 2 mm size of this specimen would eliminate the vast majority of shark species.  Also the specimen features, especially the basal plate, look much more ray like.  Even shark abrasion strength placoid scales (dermal denticles) have a thinner, more delicate basal plate.  Ray dermal denticles (rays can also have much smaller, less  than 1 mm, placoid scales) usually along mid-lines, by the eyes, etc. can be very large in size. Also ray dermal denticles are mostly for protection and abrasion strength and can be very sturdy looking in features like this specimen.

 

Marco Sr.

 

 

 

[siteseer]

13 hours ago, MarcoSr said:

 

I feel that the specimen is a ray dermal denticle based upon size and specimen features.  The vast majority of shark placoid scales (some researchers use the term dermal denticles) are less than 1 mm in size.  However,  there are some species of shark like Brambles that can have much larger dermal denticles and Brambles can also have fused dermal plates up to 25 mm.  The 2 mm size of this specimen would eliminate the vast majority of shark species.  Also the specimen features, especially the basal plate, look much more ray like.  Even shark abrasion strength placoid scales (dermal denticles) have a thinner, more delicate basal plate.  Ray dermal denticles (rays can also have much smaller, less  than 1 mm, placoid scales) usually along mid-lines, by the eyes, etc. can be very large in size. Also ray dermal denticles are mostly for protection and abrasion strength and can be very sturdy looking in features like this specimen.

 

Marco Sr.

 

 

 

 

Marco Sr.,

 

I have a bramble specimen from the STH Bonebed that is a fused group of denticles.  It's tiny.  A friend says he has the set-up to photograph it.  I'm going to bring that and a couple of scyliorhinid teeth and maybe a couple of oddball symphyseals the next time I go to Houston.

 

Jess 

[MarcoSr]

2 hours ago, siteseer said:

 

Marco Sr.,

 

I have a bramble specimen from the STH Bonebed that is a fused group of denticles.  It's tiny.  A friend says he has the set-up to photograph it.  I'm going to bring that and a couple of scyliorhinid teeth and maybe a couple of oddball symphyseals the next time I go to Houston.

 

Jess 

 

Jess

 

Your specimen must be from a very young shark.  If you can get some pictures, please post them here on TFF.

 

Marco Sr.

[old bones]

On 4/22/2020 at 4:19 AM, siteseer said:

I'm not sure but It does look like a dermal denticle.  The last time I saw one like that it was identified as coming from the tip of the snout of a shark.  Marco Sr. has looked at a lot of dermal denticles.  Maybe he can take a look.  Marcel needs something to do too.

 

@MarcoSr  @isurus90064

 

Thank you for your input on this specimen. I don't see many of these. I found a similar one in Peace River matrix a few years ago.

22 hours ago, Troodon said:

Agree looks like a shark denticle

https://www.researchgate.net/publication/311957637_Dermal_denticles_as_a_tool_to_reconstruct_shark_communities

 

Thanks for looking at this, and thanks for the excellent reference!

16 hours ago, MarcoSr said:

 

I feel that the specimen is a ray dermal denticle based upon size and specimen features.  The vast majority of shark placoid scales (some researchers use the term dermal denticles) are less than 1 mm in size.  However,  there are some species of shark like Brambles that can have much larger dermal denticles and Brambles can also have fused dermal plates up to 25 mm.  The 2 mm size of this specimen would eliminate the vast majority of shark species.  Also the specimen features, especially the basal plate, look much more ray like.  Even shark abrasion strength placoid scales (dermal denticles) have a thinner, more delicate basal plate.  Ray dermal denticles (rays can also have much smaller, less  than 1 mm, placoid scales) usually along mid-lines, by the eyes, etc. can be very large in size. Also ray dermal denticles are mostly for protection and abrasion strength and can be very sturdy looking in features like this specimen.

 

Marco Sr.

 

It is very thick and sturdy looking. Thanks so much for having a look at this, Marco Sr..

2 hours ago, siteseer said:

 

Marco Sr.,

 

I have a bramble specimen from the STH Bonebed that is a fused group of denticles.  It's tiny.  A friend says he has the set-up to photograph it.  I'm going to bring that and a couple of scyliorhinid teeth and maybe a couple of oddball symphyseals the next time I go to Houston.

 

Jess 

I would very much like to see those photos Jess.

 

[digit]

Thanks for the info, Marco!

 

I find these little squarish dermal denticles with the fluted enameled surface fairly frequently in micro-matrix from Cookiecutter Creek. Haven't picked through enough of the really fine micro-matrix from the Peace River to have seen any there (yet). These are always found while picking with the aid of my camera-microscope (viewing on a nice large flat-screen TV monitor). They turn up in the size class of matrix that passes through my 1/12" screen and is held back by my 1/20" screen (so they tend to be in the 1-2 mm size class). Sometimes I can go for days without seeing one and then I run into a streak with several appearing on my picking plate--had 2 nice ones last night.

 

I've been assuming these were shark denticles but haven't had the time (yet) to investigate these further--thought that is in the works. Here is a gallery of a number of specimens from CC Creek along with an oddity for comparison (upper left). Turns out the oddball is the smallest hexagonal myliobatid tooth plate I've ever found.

 

Cheers.

 

-Ken