Jump to content
TqB

Fish fragment? Lower Jurassic, Whitby, England.

Recommended Posts

minnbuckeye

DSC_0366.thumb.JPG.c549016247a322e13126db664a869597.JPG 

 

I love the crab claw or urchin possibility but my eye keeps going back to this spiral like thing. Does not seem like it would be a projection from these possibilities.

Share this post


Link to post
Share on other sites
Fossildude19

Maybe foramenifera? :shrug:

This piece is definitely a headscratcher. :headscratch:

Share this post


Link to post
Share on other sites
TqB

Thank you all so much for the replies - they've all made me think! Thanks especially to @ynot for marking up all the dimples!

 

One thing to consider is that there was practically no bottom fauna at the time - too anoxic - so gastropods, echinoids and benthonic arthropods just don't occur.

The fauna is pretty much all nektonic - reptiles, fish, coleoids, ammonites.

 

I'm still favouring fish ( @GeschWhat Lori - would love it to be a bit of odd coleoid or nudibranch but the shape doesn't match anything I can think of!)

 

I've taken some more photos, under water this time which is revealing.

 

I think this shows that:

 

1)  It is a definite, single structure - I'm sure it's not a coprolite or tar. See the regular, denticulate/knobbly protrusions along much of the margin.

 

2)  I'm pretty sure the white things are part of the structure and that most of the dimples, even the small ones, represent missing inclusions of similar form and size.

The specimen is worn and the smallest dimples are just the bottoms of much larger ones . (This is clearer under a microscope than in the photos I'm afraid.)

 

3)  @minnbuckeye - the apparent spiral is really just a dimpled, grooved surface, like an asymmetrical heart. See last photo below (as close as I can get with my camera, it's only 1mm across).

 

IMG_3107.thumb.jpg.59996bbe52a36ab603bc4525f1e62f2f.jpg

 

Closeup of the denticulated/knobbly margin:

IMG_3110.thumb.jpg.8005875d05a44f5ef5e4a9b35649253a.jpg

 

Showing dimples worn to various depths. I think all these were occupied by the white spheroids:

5b47480c1e785_IMG_31132.thumb.jpg.f7950097b89bdf43c2adeb557bf343b0.jpg

 

Showing that this bit isn't actually a spiral. (1mm diam)

IMG_3113.jpg.6008d4223f29274d1940f12c55a906c4.jpg

 

 

     

 

Share this post


Link to post
Share on other sites
westcoast

Really looks like crustacean.....? Maybe carried in by scavanger/predator from more oxic area...

Share this post


Link to post
Share on other sites
fossilized6s

20180712_101042.jpg.a275153ba20258e204e3548bcb606b30.jpg

 

These bumps scream crab/loster claw to me. Even though certain arthropods didn't exist on the ocean floor at the time doesn't mean it couldn't have been eaten from somewhere else and regurgitated there. 

Share this post


Link to post
Share on other sites
ynot
8 minutes ago, fossilized6s said:

These bumps scream crab/loster claw to me.

I agree.

Share this post


Link to post
Share on other sites
TqB
1 hour ago, westcoast said:

Really looks like crustacean.....? Maybe carried in by scavanger/predator from more oxic area...

 

2 minutes ago, ynot said:

I agree.

 

2 minutes ago, ynot said:

I agree.

 

Thanks - I'm certainly prepared to be persuaded of this. :) But what about the little white beads which are definitely part of it?

Share this post


Link to post
Share on other sites
westcoast
13 minutes ago, TqB said:

 

 

 

Thanks - I'm certainly prepared to be persuaded of this. :) But what about the little white beads which are definitely part of it?

Do a Google (or other) search for Kaiparowits crustacean cuticle image. I think if you find the same figure h you will see a similarity, even if yours is a lot more eroded or worn..

Share this post


Link to post
Share on other sites
doushantuo

 

 

 

seepf566655tyyy774ett77archime44e5tmedtr2m35pltwillist.jpg

 

source:

 

seepf566655tyyy774ett77archime44e5tmedtr2m35pltwillist.jpg

Share this post


Link to post
Share on other sites
doushantuo

Tanaidean decapoda are known from the Swiss Opalinuston,which is somewhat of a "black shale"

(dysoxic to anoxic claystone,perhaps)

edir:seasonal anoxia.

 

Share this post


Link to post
Share on other sites
TqB
29 minutes ago, westcoast said:

Do a Google (or other) search for Kaiparowits crustacean cuticle image. I think if you find the same figure h you will see a similarity, even if yours is a lot more eroded or worn..

Thank you, there is certainly a similarity.

I haven't seen anything like it in other Lower Jurassic arthropods from the area (lobsters are quite common in nodules above and below the Jet Rock) so it would be something unusual. :)

Share this post


Link to post
Share on other sites
fossilized6s
1 hour ago, TqB said:

 

 

 

Thanks - I'm certainly prepared to be persuaded of this. :) But what about the little white beads which are definitely part of it?

Possible Gastroliths as @doushantuo suggests. A crab eating fish that swallows rocks to help it break the shell apart. Then regurgitates the shell after the soft tissue is broken down. Just a fun guess. 

Share this post


Link to post
Share on other sites
Carl

I think I'll move over to the decapod camp. I can now easily see that as a squashed claw missing the dactyl. 

Share this post


Link to post
Share on other sites
TqB

UPDATE :)

 

I've just tested the hardness of the white spheroids (under a microscope) and it comes out as 5 (scratches fluorite, scratched by quartz, apatite and the spheroid just burnish each other).

(Should have done this first of course.:blush:)

Also, there's no acid fizzing.

 

So it's presumably apatite bone/tooth material, not calcite. (The black material is softer though, about the same as calcite).

 

Over on a Facebook page (Yorkshire Fossil Hunters), Dapedium (ganoid fish) head armour is the preferred suspect. Arthropod was the second contender but the chemistry seems to rule that out.

Share this post


Link to post
Share on other sites
TqB

Here is part of a mashed up Dapedium that I have from the Lower Lias of Lyme Regis. I hadn't realised before that the tubercles are quite discreet, hard enamelled elements within softer bone face plates. I tested the hardnesses here too and they're the same as the specimen in the thread.

Different colour preservation but I think it's convincing.

 

IMG_3116.thumb.jpg.e2298c75a5d5f3bffc5f1606eeb87ae5.jpgIMG_3117.thumb.jpg.f8cca77c7fdf62c756b3b52ccf384e43.jpgIMG_3115.thumb.jpg.bb340e82a23985694cc5ad752675f5fe.jpg

 

Share this post


Link to post
Share on other sites
Auspex

I would call the margin here 'variably amorphous' (as oxymoronic as that may sound).

~~.jpg

 

Rather chaotic for a hard organic material, no?

Share this post


Link to post
Share on other sites
Mike from North Queensland

Just a thought on some of the suggestions that I would like logically argued out even if for my own benefit as I do not have a clue what the object is.

The specimen is distorted with several areas having overlapped other sections.

Some areas are close to, as in life as I assume there was once some curvature in the surface. 

 

Crustacean - would not the hole exoskeleton be made of the same material and thus fossilise the same colour and density.

Fish external - same material with scales and head armour.

Fish teeth - the dimple size indicates that the crushing teeth would vary in size from row to row.

Isolated seep blob with secondary objects on - blob spacing too uniform and only on object.

 

Echinoid - the photo I used earlier would fossilise the same throughout but may be viable if the specimen had spines that were made from a different material than that of the body but unsure.

 

Skin with dermals may be best and the edge of interest be interpreted as margin near the mouth.

 

Mike

Share this post


Link to post
Share on other sites
Auspex

Excellent discussion!

The subject is so obscure that resolution hinged on deep knowledge of the site, by experienced local collectors.

I love it when the magic works!

Share this post


Link to post
Share on other sites
doushantuo

the fossil seems to be outlined "stylolitically" as well,at least partly.

Tarq, fig 7b from the Palaios article I posted clearly show spheroidal cuticular fragments

 

Share this post


Link to post
Share on other sites
TqB
2 hours ago, Auspex said:

Excellent discussion!

The subject is so obscure that resolution hinged on deep knowledge of the site, by experienced local collectors.

I love it when the magic works!

Thanks to all who have contributed!  

I have learned a lot from this. The byways are just as interesting as the main thread. :) 

 

2 hours ago, doushantuo said:

the fossil seems to be outlined "stylolitically" as well,at least partly.

Tarq, fig 7b from the Palaios article I posted clearly show spheroidal cuticular fragments

 

I think it's oxidised pyrite veins - there's a lot of pyrite in the formation. It could well be stylolitic solution and migration.

Yes, the spheroids look similar and may have a comparable strengthening function. I gather they're calcitic while the fish ones are shiny apatite.

Share this post


Link to post
Share on other sites
doushantuo

The fossil seems to be surrounded by small-scale polygonal faults ,outlined by (Possibly) larger grainsizes?

Thanks to everyone for rekindling an old fascination with the Jurassic of Yorkshire.:P

Still very, very fond of my (way too little) collection of the PYGS

Share this post


Link to post
Share on other sites
TqB
7 minutes ago, doushantuo said:

The fossil seems to be surrounded by small-scale polygonal faults ,outlined by (Possibly) larger grainsizes?

Thanks to everyone for rekindling an old fascination with the Jurassic of Yorkshire.:P

 

I think they're relatively recent desiccation cracks filled with pyritic sulfate crystals.

Yorkshire geology rocks. :P

Share this post


Link to post
Share on other sites
doushantuo

tell me about it:ninja:B)

2f77588t4ee44e5tmedtr2m35pltwillist.jpg

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Recently Browsing   0 members

    No registered users viewing this page.

×