Preserved fossil shark “skin”

[Doctor Mud]

7 hours ago, North said:

Must have been great feeling when you realised what you found

It was. Literally stunning  Took the whole trip to process it. Still in disbelief until I looked under the scope at home. I hope it’s also a preview of what is possible at this site. A fully articulated shark with teeth! Gotta dream!!!

[Doctor Mud]

7 hours ago, JBkansas said:

I would think this is worth publishing if you can find an interested paleontologist

I hope we can publish this. I was in touch with a Japanese scientist, but I think he only works part time on paleo. I like to put in the work reaching out and networking with scientists to find the right connection.

It can be hard to maintain momentum on these projects though since it’s a part time thing for me. 
 

So no official collaborator yet on this piece 

 

[Coco]

On 3/26/2024 at 12:44 PM, Doctor Mud said:

Thanks for the kind words.

Wonderful pictures! Did you take these? 
Incredible what it looks like up close.

Yes. About ten years ago, I had a fishmonger who sometimes had whole sharks, I could recover the jaws and skin. Unfortunately these sharks of the depths must be rarefied now, it’s been years since I saw any more.

 

I have a new camera, I should try to take pictures of other skins because for example in Mustelus asterias dermal denticles are very small and we do not see much in my photos except the white spots...

 

Coco

Edited March 27 by Coco

[Doctor Mud]

I just came across this paper that looks quite relevant to the question: "can we ID shark species based on their dermal denticles"

 

Seems like the answer is: sometimes.... Not abrasion strength denticles, but some drag reduction denticles. 

 

Can denticle morphology help identify southeastern Australian elasmobranchs? (wiley.com)

 

Elasmobranchs are covered in scale-like structures called dermal denticles, comprising dentine and enameloid. These structures vary across the body of an individualand between species, and are frequently shed and preserved in marine sediments.With a good understanding of denticle morphology, current and historical elasmo-branch diversity and abundance might be assessed from sediment samples. Here,replicate samples of denticles from the bodies of several known (deceased) sharkspecies were collected and characterized for morphology before being assigned morphotypes. These data were used to expand the established literature describing denticles and to investigate intra- and interspecific variability, with the aim of increasing the viability of using sediment samples to assess elasmobranch diversity and abundance. Denticle morphology was influenced more by life-history traits than by species, where demersal species were largely characterized by generalized function and defense denticles, whereas pelagic and benthopelagic species were characterized by drag-reduction denticles. Almost all species possessed abrasion strength or defense denticles on the snout, precluding their utility for separating species. In a separate manipulative experiment, samples of denticles were collected from sediments in two aquaria with known elasmobranchs to determine their utility for reliably separating species. Visual examination of denticles, morphometric measurements, scaled photographs, and reference collections allowed for some precise identification, but not always to the species level. Ongoing work to develop denticle reference collectionscould help to identify past and present families and, in some cases, species.

[rocket]

we have some complete sharks with dentition, Jurassic and cretaceous (attach an upper jurassic one)

I can try to do pics of the denticles if you need some, but it would take some days

 

[pachy-pleuro-whatnot-odon]

2 hours ago, rocket said:

we have some complete sharks with dentition, Jurassic and cretaceous (attach an upper jurassic one)

I can try to do pics of the denticles if you need some, but it would take some days

 

 

Wow! That's an impressive specimen!

[digit]

13 hours ago, Doctor Mud said:

I’d love to enter it in FOTM, but found it last month. I had been sitting on it while I did some background research. But then thought I should share this do others can enjoy it.

 

The buzz of finding it and sharing the excitement with you all is just like winning FOTM anyway 

Thanks for sharing! I think the excitement and encouragement to study further by the awestruck members participating in this conversation is worth more than any little digital badge.

 

To be honest when I saw the first photo of the concretion with the patterned texture I thought it would turn out to be nothing more than a fenestrate bryozoan colony which it very much resembles. Color me impressed when I saw the micro photographs and could make out the unmistakable structure of chondrichthyan denticles. I do have some contacts (no, not the ones I'm wearing) who deal with sharks and one in particular who studies dermal denticles--she calls them "shark dandruff" as they are shed and replaced throughout their lifetimes.

 

Though my contacts are rather antipodal to your location, let me pass your images around and see if I can find you any leads for potential research of this novelty. I bet you'll be picking up any concretions with this pattern on them from now on.

 

 

Cheers.

 

-Ken

[Doctor Mud]

21 hours ago, Coco said:

Yes. About ten years ago, I had a fishmonger who sometimes had whole sharks, I could recover the jaws and skin.

That was a great relationship to have! 
they are great photos! I see a lot of sharks washed up in my travels. I saw a 6 gill last week which is rare here. How do you preserve the skins? 

[Doctor Mud]

12 hours ago, rocket said:

we have some complete sharks with dentition, Jurassic and cretaceous (attach an upper jurassic one)

I can try to do pics of the denticles if you need some, but it would take some days

 

I would love to see photos when you get a chance!

[Doctor Mud]

10 hours ago, digit said:

Thanks for sharing! I think the excitement and encouragement to study further by the awestruck members participating in this conversation is worth more than any little digital badge.

 

To be honest when I saw the first photo of the concretion with the patterned texture I thought it would turn out to be nothing more than a fenestrate bryozoan colony which it very much resembles. Color me impressed when I saw the micro photographs and could make out the unmistakable structure of chondrichthyan denticles. I do have some contacts (no, not the ones I'm wearing) who deal with sharks and one in particular who studies dermal denticles--she calls them "shark dandruff" as they are shed and replaced throughout their lifetimes.

 

Though my contacts are rather antipodal to your location, let me pass your images around and see if I can find you any leads for potential research of this novelty. I bet you'll be picking up any concretions with this pattern on them from now on.

 

 

Cheers.

 

-Ken

Thanks Ken,

 

I totally agree it’s nice in FOTM to see all our best finds in one place, and it’s a really great way to summarize a months collection for TFF folk. The find and this awesome and insightful discussion is a win in my book. 
 

I still had reserves until I got it home and looked under the scope. It was on my mind for the rest of that trip! It looked different to how bryozoans normally preserve, but I needed to see under the scope to be sure. I was very happy when I saw denticles. 
 

I think I might have come across her work online while researching shark denticles. I remember smiling while reading about shark dandruff. Lucky there isn’t a “head and shoulders” shampoo for sharks. Really appreciate you checking around with your contacts. 
 

 

 

 

[rocket]

12 minutes ago, Doctor Mud said:

I would love to see photos when you get a chance!

I try to do some good ones next week

[Doctor Mud]

On 3/27/2024 at 12:09 AM, MarcoSr said:

Are you certain about the scale dimensions? 

I actually measured rather than estimated 

Hard to do it turns out on an average ruler with lines that look humungous under the scope. One denticle is spans the inside of 1mm lines on the ruler. Presuming 1mm spans the center of each line, one scale is less than 1mm long, greater than 0.5mm. Let’s say roughly 800 microns. 

[MarcoSr]

47 minutes ago, Doctor Mud said:

I actually measured rather than estimated 

Hard to do it turns out on an average ruler with lines that look humungous under the scope. One denticle is spans the inside of 1mm lines on the ruler. Presuming 1mm spans the center of each line, one scale is less than 1mm long, greater than 0.5mm. Let’s say roughly 800 microns. 

 

With the vast majority of extant shark placoid scales less than 1mm, 800 microns is a more expected dimension.  If the measurement had been above 1mm, that would have greatly reduced the number of possible species that your specimen could be.  The vertebrae look pretty eroded in your picture, so their features probably won't be useful in a family/genus/species ID unless the portions in the rock are much better preserved.  However, their size should help to eliminate a number of possible species that wouldn't get that big.  The features of the placoid scales along with the 800 micron size would provide the best chance for a family/genus/species ID.  However, you definitely need a shark expert/researcher with lots of shark placoid scale knowledge, and who is familiar with the different sharks present in the time period of your rock specimen for a possible ID.  Probably time to take the specimen to your local museum for an opinion and to try to contact some authors of papers on shark placoid scales.

 

Marco Sr.

[Doctor Mud]

Thanks @MarcoSr

I’ll definitely be reaching out to connect with some specialists. I’ve mostly had good experiences doing this. 
Getting this micro CT. Scanned will help to see the uneroded sides of the verts. It might help with the denticles but only if we can get high enough resolution. 
 

I’ll definitely post any updates on here. 

[R0b]

On 3/26/2024 at 11:42 PM, Doctor Mud said:

I hope we can publish this. I was in touch with a Japanese scientist, but I think he only works part time on paleo. I like to put in the work reaching out and networking with scientists to find the right connection.

It can be hard to maintain momentum on these projects though since it’s a part time thing for me. 
 

So no official collaborator yet on this piece 

 

@mamlambo might be able to point you in the right direction 

 

congratulations on the find

[pachy-pleuro-whatnot-odon]

3 hours ago, Doctor Mud said:

I actually measured rather than estimated 

Hard to do it turns out on an average ruler with lines that look humungous under the scope. One denticle is spans the inside of 1mm lines on the ruler. Presuming 1mm spans the center of each line, one scale is less than 1mm long, greater than 0.5mm. Let’s say roughly 800 microns. 

 

Some software packaged with digital microscopes actually includes a feature that allows you to accurately measure the size of an enlarged object by dragging a line between two points on the screen...

[Doctor Mud]

2 hours ago, pachy-pleuro-whatnot-odon said:

Some software packaged with digital microscopes actually includes a feature that allows you to accurately measure the size of an enlarged object by dragging a line between two points on the screen...

I keep meaning to get myself I digital microscope camera so I can connect it to my computer.  I think it might be time to upgrade from taking photos down the eyepiece with my smartphone! 

[Tidgy's Dad]

Great find.

[FossilNerd]

Thanks for the great read and discussion! I can't contribute much (being a invertebrate guy), but I thoroughly enjoyed watching from the sideline. I'll just be content to sit here on the bench and hold onto this bucket to catch all of the drool!

Congrats on the EPIC find!