Discussion of the Reconstructions of Nautiloids and Ammonoids

Goodness me. An aerial nautiloid? That one never made it's way into the scientific literature (yet). I suppose if it filled its chambers with helium and lost the heavy mineralised deposits then it could potentially fly, using its syphon for jet propulsion. However, there may be a stability problem without wings on the shell.

I wouldn't like to be on a plane flying through a swarm of those things though, the conic shape of the shells would act like bullets embedding the airframe.

On a slightly more serious note, here is a fantastic painting of an Ordovician nautiloid snacking on trilobites:

http://www.karencarr.com/gallery_ordovician.html
 
What are the prevailing opinions regarding the coloration and markings on ammonite/nautiloid shells? Is this simply one of those situations where nobody really knows? Over the years I've seen endless imaginings, some of which make the shells look like they're covered in zig-zag "dazzle" painting like WWI warships, or like childrens' party hats. I'm trying to figure-out paint schemes for prehistoric cephalopod shells over the next week and so far the most likely plan is to use modern mollusk shells as inspiration, but if any of the experts could point me in the proper direction it would be greatly appreciated!
Thanks!

Erich
:ammonite: :nautiloi: :nautilus: :party:
 
Hi Erich,

No time right now, but I do have an image somewhere of an ammonite with striped pigment bands still showing. I'll see if I can scan it tonight for you. In truth, no-one really knows how they were decorated; I suppose guesses can be made simply from the environment that species lived in (e.g camoflage in reef systems). It's possible lappets, only seen on some male ammonite species, may thave been brightly coloured as they were effectively for display purposes, probably to attract a mate.

As for depictions of nautiloids with reddish-brown striped patterns I'm sure they are just extrapolated from Nautilus.

Will post the image later for you.
 
Here you go Erich.

I shouldn't really be posting this as it is scanned from Neale Monk's excellent 2002 book 'Ammonites' but as Neale has on occasion contributed here, I am hopeful that he would not mind.

The upper image is of the Jurassic ammonite Liparoceras and one can make out clear banding pattens. The lower image is of the Miocene nautiloid Aturia and one can make out a trace of patterning very similar to Nautilus. With the ammonite the patterning resembles a snail rather than the familiar Nautilus patternation. Of course ammonites were a diverse bunch with many differing forms living in varied habitats so it's quite possible that was a wide variety of colouration and patterning.


I'm not aware of any more examples, but if I can find any I'll drop you a line.

Thanks!
 

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Orthocones have been found with a diversity of pigmented shells including longitudinal and transverse stripes, irregular dark blotches, cresent shaped bands, and chevron patterns. Coiled shells have been found with longitudinal stripes, transverse bars, and revolving stripes. Aturia, an Tertiary coiled nautiloid, has a pattern much like that of Nautilus.

Look in the Treatise on Invertebrate Paleontology, Part K, Mollusca 3, "Nautiloids", 1964, and Mollusca 4, Ammonoidea, 1957.
 
Thankyou Segmoria,

When I discovered those illustrations they were just too good not to borrow. The accompanying research was mine though.

Unfortunately I don't speak or type in Japanese, so I couldn't ask for permission to borrow them. Still, best keep this a secret between us two!

Thanks again!

Phil

PS, What is your avatar, I've been wondering?
 
Thanks for that, Segmoria. I had thought it was a background alien from Attack of the Clones or some such! That image is very cleverly made indeed.
 
I've just added Endoceras to the list.

Luckily it predated the others, it would have been a nightmare to have to rearrange that thread to keep in chronological order.

There is a nice little animation of Endoceras available here.
 
Below is a section of an Endocerid showing the endocones in the large siphuncle. The siphuncle of endocerids could be as large as 2/3 the shell diameter and was located on the ventral (bottom) portion of the shell. The calcareous endocones are thought to be used as counterweight to keep endocerids oriented ventral down and the shell horizontal in the water column. You can also see the septa dividing the chambers and the shell wall. I would need a transverse section thru this specimen to see if it was like Rossoceras or Cameroceras for specific ID, but it is in a large ledge of limestone and would be impracticle to remove and section. The section shown is about 50mm wide, and the length is a part of the 600mm long fossil.
From the outside it looks like a regular orthoconic nautiloid, all the neat stuff is on the inside. :smile:
 

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