Miocene marine insect?

[Gmack]

Is this an insect? Marine spider?  

[ynot]

Welcome to TFF!

This is not an insect or spider.

Hard to say what it is unless We can see the whole thing. (from different angles.)

Also, where was it found?

 

Tony

 

[Gmack]

Thanks tony.  Found in mudstone from Miocene seabed in New Zealand 

[Gmack]

Thanks tony.  Found in mudstone from Miocene seabed in New Zealand     The shape is like a piece of lobster tail 

[FossilDAWG]

Nothing about this specimen resembles any arthropod, to my eye.  There is nothing I can see that suggests exoskeleton, segmented legs, a cephalothorax joined to an opistosome by a narrow pedicel, or any other feature that would be expected of a spider.

 

Just what the specimen actually is, is not obvious to me.  It might be a section through a somewhat crushed gastropod, but that's a low-confidence guess.  It's clearly a section through something.

 

Don

[ynot]

Can You post pictures of the bottom and the broken edge?

Tony

[FossilGuy1024]

Hello Gmack,

     Basically the whole piece itself is an internal cast of a shell. After the animal died and before it became filled with sediment serpulid worms began living inside the shell and created their tubes. Eventually the surrounding and filling muck became stone and the original shell dissolved or fell away leaving the internal cast. The worm tubes  are still contained in the internal cast and the curving parallel lines are the two sides of the tubes where they attached to the inside of the original shell.

 

Welcome to TFF and keep up the good work.

[jhw]

Interesting looking piece. My first thought would be bivalve or gastropod cross section.

[ynot]

1 hour ago, FossilGuy1024 said:

Hello Gmack,

     Basically the whole piece itself is an internal cast of a shell. After the animal died and before it became filled with sediment serpulid worms began living inside the shell and created their tubes. Eventually the surrounding and filling muck became stone and the original shell dissolved or fell away leaving the internal cast. The worm tubes  are still contained in the internal cast and the curving parallel lines are the two sides of the tubes where they attached to the inside of the original shell.

 

Welcome to TFF and keep up the good work.

Great call!!

I agree with this.

Tony

[Gmack]

Thanks.  You guys are awesome. Appreciate the detailed answer. Makes sense that it is a cast.  Where it is from is mostly shell with some crab bits. People report whalebone as well.