Preserved fossil shark “skin”

[Doctor Mud]

Hello everyone,

 

I was recently looking at one of our local beaches. I didn’t have a lot of time so went where most people go. Sometimes even though it is picked over you might still find something special. I often think, there could be just a few mm of sand covering up something special! 
 

I saw this sitting there waiting for me and thought. That’s cool. Level of excitement maybe a 6 out of 10? I hadn’t seen associated verts like this at this site and was thinking “shark or fish” 

 

(p.s. photos are at home after finding it in better light. But pretty much what saw on the beach)

 

 

I was leaning towards shark and then flipped it over. Excitement went to 9/10!!

 

I couldn’t believe what I was seeing. This looked like preserved shark “skin” or at least in situ dermal denticles. A first for me at this site. 

If you’d like to join me down a wormhole on learning about shark dermal denticles. Read on! This is a normal journey I take as I learn as much as I can about each fossil. Every fossil has something to teach. About the environment the animal lived in or the creature itself. I’ve learnt a lot about biology/ecology this way. 

 

if you zoom in under the scope, there are 2 layers of denticles. The top one most visible in the above photo seems to be looking at the base of the denticles from underneath, like a skin has folded on itself 

these look like the “roots” of the denticles.

In the photo below. Each one about 1-2mm across

 

 

In the photo below is the underside of the top of some denticles A tricuspid type. A few mm across. So zoomed in more than the above photos. 

 

 

these look like the “drag reduction” type tricuspid denticles top left in the figure below. This figure shows that sharks will have different types of denticles on different parts of the body. The proportions and types differ depending on ecology. Pelagic (requiring drag reduction) vs bottom feeding (demersal) requiring protection from abrasion. 

 

 

I searched around the specimen and found a few examples looking at the top of the denticles. Below. Unedited Photo above with red sketch to highlight features below. 

 

 

denticle is a couple of mm across. You can see the crests typical of the drag reduction type.

 

 

below: looking side on at an individual denticle. The “root” at the bottom and tricuspid denticle on top. 

so how to move forward? The matrix isn’t acid soluble. But I’d like to be able to clearly see some complete denticles. Gentle air abrasion? 
 

I’m not sure if an ID to family will be possible. I have shown a shark tooth/denticle expert (from Japan) and he thought we could narrow it down to Triakidae (hound sharks) or Pentanchidae (deep water cat sharks). 
 

The age range is Miocene- Pliocene for the coast in this area.  I think Late Pliocene for this based on lithology. 
 

So now…..where is the rest of the shark? 
 

Thanks for following along!

 

 

 

Edited March 26 by Doctor Mud

[Doctor Mud]

Thought you might find this funny. One of the most common sharks caught by people here surf casting belongs to Triakidae. Locally called “rig” (Mustelus lenticulatus).

I thought maybe it could be a candidate?

 

I saw a head someone had left behind and took it home to look at the denticles.

 

I froze it first so it didn’t smell (much)

 

mouth showing teeth and denticles. This shark feeds on crustaceans. 

 

 

Zooming in on denticles (above) They are all the “abrasion strength” type. Which makes sense as it is demersal. 
I didn’t have a body available but perhaps it has some other types on the body. 
 

 

 

 

Edited March 26 by Doctor Mud

[rocket]

1 hour ago, Doctor Mud said:

Hello everyone,

 

I was recently looking at one of our local beaches. I didn’t have a lot of time so went where most people go. Sometimes even though it is picked over you might still find something special. I often think, there could be just a few mm of sand covering up something special! 
 

I saw this sitting there waiting for me and thought. That’s cool. Level of excitement maybe a 6 out of 10? I hadn’t seen associated verts like this at this site and was thinking “shark or fish” 

 

(p.s. photos are at home after finding it in better light. But pretty much what saw on the beach)

 

 

I was leaning towards shark and then flipped it over. Excitement went to 9/10!!

 

I couldn’t believe what I was seeing. This looked like preserved shark “skin” or at least in situ dermal denticles. A first for me at this site. 

If you’d like to join me down a wormhole on learning about shark dermal denticles. Read on! This is a normal journey I take as I learn as much as I can about each fossil. Every fossil has something to teach. About the environment the animal lived in or the creature itself. I’ve learnt a lot about biology/ecology this way. 

 

if you zoom in under the scope, there are 2 layers of denticles. The top one most visible in the above photo seems to be looking at the base of the denticles from underneath, like a skin has folded on itself 

these look like the “roots” of the denticles.

In the photo below. Each one about 1-2mm across

 

 

In the photo below is the underside of the top of some denticles A tricuspid type. A few mm across. So zoomed in more than the above photos. 

 

 

these look like the “drag reduction” type tricuspid denticles top left in the figure below. This figure shows that sharks will have different types of denticles on different parts of the body. The proportions and types differ depending on ecology. Pelagic (requiring drag reduction) vs bottom feeding (demersal) requiring protection from abrasion. 

 

So now…..where is the rest of the shark? 
 

Thanks for following along!

 

 

 

wow, incredible find...

Rest of the shark, go in the field with some sausages, might be it will come 

[RJB]

Holy Cow Dr. Mud.  Thats incredible!  Purty dang cool too.   First time I've ever seen something like this. 

 

RB

[Coco]

Hi,

 

Your find is incredible and so rare ! There is no doubt !

 

I have some interesting shark skin pics :

 

Centrophorus squamosus

 

Centroscymnus coelolepis

 

Mustelus asterias

 

 

I don't have more close-up, perhaps I have to do more...

 

Coco

Edited March 27 by Coco

[MarcoSr]

This is an incredible find.  Fossilized shark skin with placoid scales is extremely rare.  I think it is clear that the scales are indeed placoid scales from your pictures.  The below picture shows different fish scales.

 

 

 

 

Are you certain about the scale dimensions?  The vast majority of extant shark placoid scales are less than 1mm and most are less than .5mm.  If they are as large as you have stated, their size and shape should really help to ID the specimen.

 

One extant shark with larger than 1mm placoid scales is Centrophorus squamosus (Leafscale Gulper Shark).  Below are pictures of 3 Leafscale Gulper Shark placoid scales (2mm size) that I received from @Coco.

 

 

Scale 1

 

 

 

 

Scale 2

 

 

 

Scale 3

 

 

 

 

 

 

Marco Sr.

[pachy-pleuro-whatnot-odon]

2 hours ago, Doctor Mud said:

Hello everyone,

 

I was recently looking at one of our local beaches. I didn’t have a lot of time so went where most people go. Sometimes even though it is picked over you might still find something special. I often think, there could be just a few mm of sand covering up something special! 
 

I saw this sitting there waiting for me and thought. That’s cool. Level of excitement maybe a 6 out of 10? I hadn’t seen associated verts like this at this site and was thinking “shark or fish” 

 

(p.s. photos are at home after finding it in better light. But pretty much what saw on the beach)

 

 

I was leaning towards shark and then flipped it over. Excitement went to 9/10!!

 

I couldn’t believe what I was seeing. This looked like preserved shark “skin” or at least in situ dermal denticles. A first for me at this site. 

If you’d like to join me down a wormhole on learning about shark dermal denticles. Read on! This is a normal journey I take as I learn as much as I can about each fossil. Every fossil has something to teach. About the environment the animal lived in or the creature itself. I’ve learnt a lot about biology/ecology this way. 

 

if you zoom in under the scope, there are 2 layers of denticles. The top one most visible in the above photo seems to be looking at the base of the denticles from underneath, like a skin has folded on itself 

these look like the “roots” of the denticles.

In the photo below. Each one about 1-2mm across

 

 

In the photo below is the underside of the top of some denticles A tricuspid type. A few mm across. So zoomed in more than the above photos. 

 

 

Wow! What an amazing find! I've seen pieces like this being advertised online as from the Early Cretaceous Waldhurst Formation in Britain, but have seen very few outside of that. And this one is in much better and more recognisable condition that those specimens! I'm not generally overly interested in shark remains, but this is just really, really cool! Absolutely crazy!

 

Since finds like these are so rare, however, I'd be very careful in prepping the fossil further, whether by chemical means or mechanically. For, if the matrix is unresponsive to acid, it might respond better to a base, such as kaliumhydroxide. Yet, I'd say the risk of damage to the fossil is just too high. Even with an abrasive, it's often not recommended using this technique on teeth, due to it causing damage to the enamel. And since these scales are pretty much made of the same material, I wouldn't risk it...

[Coco]

@MarcoSr your pics are marvelous, as usual.

 

I agree with @pachy-pleuro-whatnot-odon this fossil is too important to risk preparation by someone other than a great expert.

 

Coco

[Doctor Mud]

1 hour ago, rocket said:

Rest of the shark, go in the field with some sausages,

Sausages for me?  Or to lure out the lurking shark. I’ve been known to enjoy a few cooked sausages on the beach in the field for sure! 

[Doctor Mud]

49 minutes ago, Coco said:

I have some interesting shark skin pics :

Thanks for the kind words.

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

[Doctor Mud]

35 minutes ago, MarcoSr said:

Are you certain about the scale dimensions?

This is an estimate I’ll get some accurate measurements. I need to get a camera set up so I can calibrate and use digital software to take measurements. But I’ll easily be able to compare with a ruler for now!

 

wonderful photographs of the Centrophorus scales. As always great photographs of tiny treasures. I’ll check those dimensions and get back to you 

[Doctor Mud]

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

Since finds like these are so rare, however, I'd be very careful in prepping the fossil further, whether by chemical means or mechanically.

Very wise words indeed.

I’m scared to do anything more at this stage. I did a freshwater soak just in case to get rid of salts (coastal site) and applied a very very dilute consolidant.

 

The first thing I’d like to do is get it micro CT scanned. It might be possible to digitally isolate some denticles? We can get < 10 micron resolution these days with neutrons. 
 

And thanks for sharing my excitement! I didn’t dream of finding something like this. I have always wanted to find associated shark teeth. But associated denticles with vertebrae will do nicely as well 

[Doctor Mud]

26 minutes ago, Coco said:

I agree with @pachy-pleuro-whatnot-odon this fossil is too important to risk preparation by someone other than a great expert.

Me too!

one of the great things about this site (TFF) So much experience and expertise. I’m sure all will be revealed and the story of this piece told. 

[Frightmares]

Wow, what an awesome find!

[Jaybot]

Wow!  Goes to show, you never know what you will come back home with.

[Fin Lover]

Amazing find!  Definitely should be a FOTM entry.  

[JamieLynn]

thank you for posting all that fantastic (Fintastic?) information! I find tiny denticles in my micro matrix and have found a small section of Cretaceous shark cartilege a while back in North Texas and have not really done much research beyond that. So this is very helpful. 

 

 

[North]

Congratulation for your find.

Must have been great feeling when you realised what you found.

[JBkansas]

Definitely looks like there's another layer of skin beneath the surface. I would think this is worth publishing if you can find an interested paleontologist.

[jpc]

What a great find.  I agree that this should not be prepped any more, except with a microCT.  Might be a good candidate for a museum donation, if that suits you. 

 

I had planned to go fossil hunting this weekend just to find an entry for Fossil of the Month.  but now I will stay home and do other things. 

[Fin Lover]

19 minutes ago, jpc said:

I had planned to go fossil hunting this weekend just to find an entry for Fossil of the Month.  but now I will stay home and do other things. 

I wish I could just will myself into finding a FOTM! 

[rocket]

6 hours ago, Doctor Mud said:

Sausages for me?  Or to lure out the lurking shark. I’ve been known to enjoy a few cooked sausages on the beach in the field for sure! 

I thought to attract the shark. But sausages work for me too 

[jpc]

2 hours ago, Fin Lover said:

I wish I could just will myself into finding a FOTM! 

It usually doesn't work  : )

[Doctor Mud]

14 hours ago, Fin Lover said:

Definitely should be a FOTM entry.  

 

12 hours ago, jpc said:

I had planned to go fossil hunting this weekend just to find an entry for Fossil of the Month. 

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 so others can enjoy it.

 

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

 

Thanks everyone!

Edited March 27 by Doctor Mud

[Doctor Mud]

8 hours ago, JamieLynn said:

thank you for posting all that fantastic (Fintastic?) information! I find tiny denticles in my micro matrix and have found a small section of Cretaceous shark cartilege a while back in North Texas and have not really done much research beyond that. So this is very helpful. 

Glad the information is useful. There are many papers out there looking at dermal denticles. There are a few recent ones looking at more recent (Holocene) changes in shark communities in response to fishing too. Being so small I guess you might get denticles more often in a random sediment sample than larger teeth.