Jadeite possibly ?

Hi Judy! Glad to see you posting! Love your kitty in the basket, I've got one that just can't seem to stay off my keyboard so if I end up posting something like llllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllll that's why LOL!

Ok not to stray too far off topic, I guess I didn't realize that ammonites were extinct. I suppose I'd always assumed they were a form a nautilus but I Googled and I see that they were more closely related to a different modern species. Huh.

 

Kolbert explains that the ammonites had teeny eggs and when the cataclysm hit, the dust fallout had more impact on the water's surface where they were floating. The nautiluses had large eggs and were lower down so survived. At least, that's the theory.

 

I bought these at a trift store. I think they are 2 halves of the same shell (about 5" across), possibly nautilus but could be ammonite:





These things aren't exactly uncommon. You can easily find them on eBay. They mostly seem to come from Madagascar.

The inside cells were partly hollow with a light crystal coating, a bit like a geode:


The patterning on the outsides can be very elaborate:


This one seemed to be opalized. Moving it around in the light gave flashes of bright red:


I've read that ammonites could grow to huge sizes - 10ft across.

 

Those are gorgeous!!

 

I remember when you got those! According to Kolbert, the animal lived only in the outermost chamber. No one knows what they looked like or how they moved because of course the soft tissue did not survive.

 

There are some fossils sites in the world where soft tissues were preserved. The Burgess shale in British Columbia is one of the best know. Other, similar deposits have been found in Iceland and China. The creatures trapped there apparently sank into an anaerobic patch of water - no oxygen, therefore no decomposition, and shale is very fine silt so remarkable detail was preserved. Some of those fossils look like little more than smudges. One was so weird in its reconstructed shape that they named it hallucigenia.

 

Here's a good site on the Burgess Shale. They even show 3D models and animations.

http://burgess-shale.rom.on.ca/en/fossil-gallery/list-species.php

 

Those are cool.