Discussion in 'Cephalopod Fossils' started by Architeuthoceras, Oct 22, 2006.
What is this a fossil of ? it is cephalopodan.
a few more pics.
no idea....but in that last shot it looks like a ginormous statolith!
Or eye lens... but 11cm would be huge, plus the lenses aren't concave on the inner surface...
Looks more like bone to me, but I'm sure it's not! It's not a huge ammonoid spine base or something like that?
My only thought is that it is a really big protoconch... or maybe an aptychus. Once again, just wildly guessing.
Phil got it!
I think, basically just guessing, that it is a node (can't really call it a spine) on the shell of a coiled nautiloid. It is from the Mississippian Chainman Shale where I find a few small coiled nautiloids. This is the thickest piece of shell I have ever found though. Below are a few pics of some of the small nautiloids showing the nodes running along the flank close to the umbilical shoulder. Doing a few calculations on the ratio of diameter/shell thickness of the smaller ones I come up with a diameter of between 450mm and 1050mm (probably closer to the upper figure, shell thickness was greater on the venter where I had to measure some than on the flanks where the nodes are), making it a pretty big shell.
a few more, and a closeup of something growing on the shell, probably a bryozoan
I agree about the bryos they look very like ones we get over here growing on shells, rock, seaweed.........etc!
Thanks Jean, I guess I really should go and take a good look at the ocean one of these days and see just how some of the things I find as fossils actually live, and how they look alive.
Kinda hard for an old desert rat though.
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