Colour banding in ammonoids

Thanks all. Yes D, I think I'm going to leave it alone for a while!

Here attached is a typical roadside encounter on the way to that mountain. They don't look very impressed.
 

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Sooo cool! Are they wild or domestic without fence? If they are wild, it is an unusual replacement for our deer (and I 'd guess moose or elk in the northwest) .
 
Here is a Russian Jurassic ammonite Funiferites allae (family Cardioceratidae), 60 mm, from Ryazan region, Middle Jurassic (callovian). This is a macroconch without living chamber. This specimen demonstrated alternating light and dark colour bands. These bands are visible only on outer layer of the shall. But I don't know, this is a true colour pattern or a false colour pattern. Specimens like this are very rare, as usually we find ammonites Funiferites without colour bands.

 

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I don't know. If I was able to do the chemical analysis of a small part of the shell, I could to determine is there pigments (for instance, the melanin) or not. There are no information about Cardioceratidae's color pattern in the literature, but true color patterns of others ammonites have similarity to what we can see on my photo. There are color bands at the top layer of the shell and these bands can fade away because of the sunlight. I think, it may be true colour pattern.

Here is a another specimen Funiferites sp., 30 mm. Light part of the ammonite's shell on the top of the image hanged out of Jurassic clay before it was found and colour bands faded away because of the sunlight.

 

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It looks a lot like the color pattern of the Triassic ammonoids at the start of this thread. I don't know if they fade in sunlight like yours do, but they are rare, and from different areas of the outcrop will either have the patterns or not.

Very nice fossils. :cool2:
 

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