What is that thing?

[David in Japan]

Good evening TFF friends.

 

I have found the following fossil few time ago in amakusa, japan.

It is a cretaceous formation (santonian) called himenoura formation.

 

 

It is a small round fossil of only 2 to 3mm. It has a conical shape with kind of regular growth circle. On the picture you cannot see it but it is covered with enamel.

 

It is kind of common fossil in the part of the formation where cretalamna' s tooth are abundant. Could it be a kind of dermal dentical or is it something else? 

 

Thank you very much for your help.

 

David

From above. 

There is still some matrix on the upper part but the fossil is perfectly round.

Edited December 12, 2017 by David in Japan

[David in Japan]

Here you can see the same kind of fossil still inside the matrix but still covered with enamel.

[Tidgy's Dad]

Can't help but very interesting! 

[Peat Burns]

Cast of shark or bony fish vertebra , I think

[Innocentx]

What appears to be round may instead be coiled. Removal of remaining matrix would tell.

[izak_]

+1 for fish vertebra cast 

[abyssunder]

Fist picture tells that it might be a little curvature related to the main axis, but the second picture makes me think there is a symmetry which continues up in the matrix, revealing that it might have a biconical geometry, so I think the vertebral centrum could be a good guess.

 

[David in Japan]

And I think you are all right about it! thank you very much!

 

I feel so dumb... In fact following your comments I remembered I still have some of the original Fossil's matrix in a bag, so I search it to see if by any miracle I could find something and It happened that I found fragments of vertebra.

 

Thank you very much for your help.

[kerrimarie805]

21 hours ago, David in Japan said:

Here you can see the same kind of fossil still inside the matrix but still covered with enamel.

Covered with enamel, like our teeth or formed during fossilizing process?

[David in Japan]

 

14 minutes ago, KraZshardLady said:

Covered with enamel, like our teeth or formed during fossilizing process?

I do not know if it is really enamel you can see on the third picture. However it is really similar to the enamel you can find on teeth from this formation.

 

At the beginning i thought the mysterious fossil was dermal denticle.

 

Concerning the shark teeth or denticles, they are made of enamel however this enamel is slightly different from mammal enamel. I even think that there is an other word for shark enamel (there is 2 different word in japanese).

 

When we find fossil tooth enamel has been replaced by minerals during permineralisation but keeps its characteristics wich make it so different from bones for exemple(not an expert so if i am wrong please correct me).

[kerrimarie805]

The enamel in that third pic looks so much like the enamel that is found on old dishes and decorative household items! I often see it in the sherds I find, but my husband has a few pieces that just look like broken pieces of milk glass or enameled dish stuck to a piece of iron. I guess I'm done laughing at him for prepping them just to find out for sure!

[Plax]

any number of things can get phosphatized (black and shiny) in the fossil record; particularly in lags. It doesn't look like half a vert to me but guess it would have to be if one saw a complete one.