Colour banding in ammonoids

but not an ammonoid amongst them. Did you look at the Turek paper? Apparently there are more than 40 specimens of the Tarphycerid Peismoceras pulchrum showing colour patterns and about 20 specimens of "Cyrtoceras" parvulum.

Here's a quick sketch of the growth lines and colour bands on the little Griesbachian beast.
 

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Some ammonoids from Crittenden Springs showing preserved color patterns:


Owenites koeneni, showing transverse bands.


"Dieneroceras subquadratum", showing longitudinal stripes.


Dieneroceras spathi, showing a dark stripe on the umbilical wall and on the venter (not very visible in this photo).

Photographed under water, hence all the bubbles.

From the collection of Jim Jenks (with gratitude for permission and help), you'll notice his name in the acknowledgments of both the Gardner & Mapes and the Mapes & Sneck papers.
 

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These are beautiful specimens Kevin. Thanks for posting them!

How large are they?

Interesting to see the bunching together of transverse bands on parts of the Owenites.

Did I read somewhere that only about 1 in 500 has colour patterns preserved?
 
Really lovely.

Is it true that the transverse bands are parallel to the growth lines (unlike my Griesbachian example)?

Browsing a bit further on preserved colour patterns I came across this full body rendering of the reconstructed pigmentation in a Chinese Cretaceous dinosaur. Amazing!

I made a page showing some invertebrate examples here.
 

a closer look (click image for full size), yes, they follow the growth lines. They seem to have taken the easy way as opposed to nautilus, that knows when to stop so the top of the shell is patterned and the bottom white, or some of them old orthocones with zig-zag patterns. Probably a lot of different ways for these things to create a pattern on the shell. :smile:
 

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I don't know. Fossil ammonoids from Crittenden Springs are probably the best preserved Early Triassic fossils in the world. Even so, like Hajar says, only about 1 in 500 have the color pattern preserved. Fig 1 in This paper (pdf) (from This page), shows a stratigraphic section from Crittenden Springs, all fossils with the color pattern preserved come from the 25-50mm bed with "D. subquadratum" (about the middle). So this preservation is rare even in the bed it occurs in.
 
but as I draw this and notice the sulcate venter (as seen in this Jurassic Paracenoceras) indicated by the fine growth lines I wonder if this might be a nautilid and not an ammonoid at all.
 

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