Colour banding in ammonoids

Hajar

Haliphron Atlanticus
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#1
I just noticed that this little basal Triassic ammonoid has very distinct (when wet) orange colour bands spaced at about 2 mm apart, close to, but crossing, the very fine growth lines. First time I see this, though I know it has been recorded from Triassic ammonoids elsewhere. Does anyone else have examples?
 

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DWhatley

Cthulhu
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#8
I know you (Kevin) are kind of against messing with fossils but is there something non-destructive you can put on them that will allow them to show the colors like that (like an oil) without having to wet them?
 

Hajar

Haliphron Atlanticus
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#9
I wouldn't coat this D. It could be an important specimen.

Does anybody know of pre-Triassic examples of ammonoids showing relic colour patterns?
 

Architeuthoceras

Architeuthis
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#10
Hajar is correct, it may be important, wetting it once in a while to photograph is enough. You never know how some coating will react with the fossil, or color in this case.

I did find some Mississippian Goniatites with a dark pattern on a light calcite replacement, looked kinda like the pattern on Nautilus shells. Then I found another with the plant roots still in place and saw what really formed the pattern. :oops:

Klug et al, have something to say, especially about the radial color bands, whether this applies to all radial bands I don't know.
 

Hajar

Haliphron Atlanticus
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#11
Thanks Kevin. I have that paper, but it does not discuss true colour patterns, rather black (primarily conchiolin) structures located at terminal or former apertures. They write "formation of all of the structures presented herein has the same underlying cause, i.e. some kind of stress, but with varying results: injury (black stripe), adverse conditions at any growth stage (black aperture), interim growth stops (megastriae; ‘false colour bands’) and terminal growth (black band)."
 

Hajar

Haliphron Atlanticus
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#14
Here's a later update on the Crittenden Springs ammonoids, from Revue de Paléobiologie Vol. spécial 8 (2000):

"The relationships of color patterns and habitat for Lower Triassic Ammonoids from Crittenden Springs, Elko County, Nevada
Glen E. GARDNER, Jr. & Royal H. MAPES

Abstract
The Lower Triassic Crittenden Springs ammonoid fauna from Nevada is extremely diverse, with thirty-two species. Of the twenty-nine taxa represented in the Ohio University collection, fifteen show evidence of having color patterns or some kind of shell coloring in life. There are three types of color patterns exhibited in the ammonoid fauna. These three types are as follows: 1) monochromatic (Preflorianites toulai, Arctoceras sp., Flemingites russelli), 2) transverse bands (Owenites koeneni, Paranannites aspensis, P. mulleri, Prosphingites slossi, Juvenites septentrionalis, and J. thermarum), and 3) longitudinal stripes (Dieneroceras knechti, D. spathi, D. subquadratum, Kashmirites sp., Wyomingites whiteanus, and Xenoceltites sp.). After the color pattern documentation, all the Crittenden Springs taxa were integrated into the WESTERMANN (1996) paleoecological ammonoid habitat model.
After integration, all of the ammonoid taxa having transverse color patterns (six taxa) clustered in the planktonic-vertical migrator habitat of the basin biofacies at depths of less than 450 meters. With one exception, all of the ammonoid taxa having longitudinal color bands (six taxa) clustered in the planktonic-drifter habitat of the inner slope and platform biofacies at depths of less than 125 meters. And, all three of the monochromatic taxa clustered in the nektonic and demersal-nektonic habitats of the inner slope and basin at depths no greater than 125 meters. The taxa without observed color patterns also clustered in these latter two habitats.
Thus, within our limited data set, the consistent distributions of species with and without color patterns provide independent support for the habitat divisions within the WESTERMANN Model. Also, the consistent similarities in coloring pattern distribution as compared to shell form and habitats indicate that type of color pattern and habitat are closely related paleobiological phenomena for Lower Triassic ammonoids."
 

Hajar

Haliphron Atlanticus
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#16
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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Architeuthoceras

Architeuthis
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#17
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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Hajar

Haliphron Atlanticus
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#19
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?
 

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