Please post any comments or ideas about the Reconstructions of Nautiloids and Ammonoids (http://www.tonmo.com/forums/showthread.php?t=3684) thread here.

Thanks,

Phil

DAG-NABBIT PHIL! I'm supposed to be WORKING :shock:

Great collection of illustrations Phil. Thanks for compiling them.

In your amazing joining text, you mention that some of them are believed to be bottom dwellers. My question is: How do we "know" where they lived within the water collum?

I know all paleontological theories are based off of scant evidence and some are pure conjecture, but I am wondering if there is "special" evidence for these fossils that can distinguish the swimmers from the bottom dwellers?

I know some fossils are found within the skeletons of free swimming animals (Icthyosaurs, Plesiosaurs, etc..) which suggests the Nautiloids and Ammonoids were taken mid-water; but this could also be explained by bottom hunting.

And maybe this is my own lack of experience with these fossils, but I am having a hard time seeing an Ammonoid with a shell over 2m across swimming freely.

Anyway, great post!! I'm always salivating over iformation like this. :smile:

These are very nice reconstructions, most are just as I have had them pictured in my minds eye.

Only one, Pravitoceras, could be fixed, and I dont have a clue as how to fix it :hmm: The early whorls are coiled normally so the venter would be towards the outside (or the convex side) of the shell. At maturity it coils the opposite direction so the venter would now be on the inside (or the concave side). Most ammonites (according to a Nautilus model) are oriented with the funnel ventral, and the eyes dorsal (? is this the same with squid & octopuses), just the opposite of the reconstruction, unless the animal twisted 180 degrees in it's shell. Of course if you drew it that way it would look upside down. Anything that grew a weird shell like that was bound to be peculiar to start with.

Anyway, Thanks for posting these Phil, I did get a little work done today :wink:

Hmm....I see what you mea Kevin. It would be interesting to see a Pravitoceras sectioned so that the path of the siphuncle could be traced. Unfortunately, the only source of information on Pravitoceras I had to go on was Google and almost all of the 25 or so sites that mentioned it were in Japanese, mostly offering specimens for sale. Hence my pitiful two sentences!

My question is: How do we "know" where they lived within the water collum?

I know all paleontological theories are based off of scant evidence and some are pure conjecture, but I am wondering if there is "special" evidence for these fossils that can distinguish the swimmers from the bottom dwellers?

Hi Arthur, thanks for the kind words!

I took the environmental conditions for the ammonoids and nautiloids from a combination of Neale Monk’s book “Ammonites”(2002), Cyril Walker and David Ward’s “Eyewitness Handbook: Fossils” (1992) and Blackwell Publishing’s PaleoBase 2 (2003). From what I’ve read in these sources and others, I think fossil cephalopod depth estimates and environmental conditions are based largely on the following combination of factors:

1) Type of rock they are deposited in.
2) Shape of shell, thickness and complexity of sutures.
3) Angle of the living chamber aperture.
4) Associated animals
5) Flotation experiments using actual and computer models.

Type of rock

I have read that most ammonoids were not supposed to be able to withstand depths of deeper than 200m at maximum, any deeper then they would implode, though it is possible that a few particularly tough-shelled species such as Lytoceras may have been able to reach a depth of 800m (this depth seems to vary with which book one picks up, Lytoceras’ depth was apparently suggested by Westerman in 1996 but it does seem excessively deep). Most, of course, are thought to have lived in much shallower water than this. If, for example, deposits of ammonoid shells of a specific species are found in deep water anoxic black shales, as is the case with some of the Clymeniina and goniatites, then it follows that these animals probably lived higher in the water with the shells drifting down after death. Otherwise they would be living in conditions that were clearly unsuitable for.

On the other hand, other goniatites and some ceratites are common in limestone deposits which are thought to originate from coral reefs, this would indicate that they preferred shallow-water continental edge environments. Similarly, the Jurassic deepwater limestones of the Western Mediterranean are particularly rich in ammonites of Phylloceratina and Lytoceratina.



Shell form

Ammonites have a stronger shell form than nautiloids as in most species the septa are much more tightly packed together with complex suture patterns, but the shells tend to be much thinner. One would think that they could have colonized deep water habitats easier than nautiluses but this does not seem to the case and deep water fossils are rare. Two possible theories about this are that they were therefore able to produce shells much quicker than nautiluses using less shell-material giving them a faster growth rate, alternatively, the complex sutures could have been in response to predation as a complex ammonoid shell would be harder to break than a simple nautiloid shell.

Streamlining is obviously important in consideration of lifestyle, thin disc-like shells would clearly cut the water easier than a glob-shaped ammonite or one covered in spines due to increased drag. That not necessarily imply that all globular ammonoids were bottom dwellers though! Some may have buried into the sediment, possibly the bizarre triangular Solicylmenia may have done this.

The very shape of the odd heteromorphs does not seem to indicate a creature capable of swimming and it is thought these may have simply drifted on the tide. Even if they had a siphon (doubtful) the miniscule jet of water they could produce would have simply made them rock or spin in circles! Unable to control their direction, if at all, it is unlikely that they would have been active predators and probably just drifted about hunting plankton.



Angle of aperture/floatation studies

The angle of the aperture is very important in considering where in the water the animal would have lived. Using computer modelling, many ammonites have been reconstructed to determine exactly how they would remained buoyant in the water. Most heteromorphs have the aperture angled upwards as can be clearly seen in the nice drawing of Scaphites, this would indicate that these animals would not be capable of hunting in the sediment. Most more conventionally shaped ammonites were orientated in a similar manner to Nautilus.

There were exceptions, for example the Late Cretaceous ammonite Baculites is thought to have been orientated vertically with the head downwards and probably resting on the sediment; although it resembled an orthoconic nautiloid it lacked the counterbalancing mineralising deposits in the shell that orientated the nautiloids horizontally, thus the shell would have floated above the animal.

Many studies have been done on heteromorph ammonite orientation; here is a great link should you wish to read further:

http://palaeo-electronica.org/1998_1/monks/text.pdf


Associated animals.

Other fossils can help to indicate whether the animal lived in the water column or not. A mixture of corals, crabs or bivalves may indicate a bottom-dwelling lifestyle for example.

In short, researchers use a combination of the above factors in trying to determine habitats for these creatures. As you say, much is speculation but quite a lot can be inferred from rock-type alone!

(Hope that is of some interest. It took 2 hours to write as my computer crashed half-way through and I lost half of it!)

All the best,

Phil

WOW!! :shock:

Ask and Ye shall receive!! Thanks for the detailed answer Phil.

For some reason, the rock type never came to mind when I was thinking of these fossils. Which is silly of course, as the matrix something is found in is as important as the fossil itself.

This fact should have kicked me in the teeth as I use it when I do any acheology work. It's all about context and Matrix = Environment.

Anyway, before I go hide my head from scholarly shame, Thanks so much for the detailed answer and your willingness to spend the time typing it out. Lots of info there and well written.

Cheers,

WOW!! :shock:

Ask and Ye shall receive!! Thanks for the detailed answer Phil.

Ditto :notworth: :notworth:



(Westerman in 1996) also has a few reconstructions that are thought provoking. Some with tentacles and clubs reaching behind the shell to grab (or fetch) a fish, and a gyrocone akin to Crioceratites hanging on a sprig of seaweed like a seahorse with a large transparent umbrella like net between its arms. All copywrited (in that pricey book "Ammonoid Paleobiology") so I don't dare scan it.

great info Phillipo ! & images as I'm sure we've all got millions of glossy pics of empty shells.
you've been bathing in Omega 3 again !

Archy, as you're obviousy an info Hoover I can strongly recommend "Ammonites" by Neal Monks as essential to your library, it's a great read.

Kevin, get back to work !

Keef

Archy, as you're obviousy an info Hoover ...

Hehe, you've noticed? :smile:

When I find a source of information on a topic that is immensly interesting to me, I tend to go digging for the answers to questions in my mind.
I can be a bit overzealous though. Just ask those I have PM'ed. :roll:
I just wish I could provide more to the topics than endless questions, and half-baked theories. :oops: Anyone have questions about sub-arctic archeology or cooking? :smile:

Anyway, Thanks for the book suggestion Spartacus and I will most assuredly be looking it up.

Cheers,

no sweat, just passing on what was passed on to me being a fellow hoover !

Keef

I've added Kosmoceras to the list as I missed it off by mistake when I originally posted the details. It took a while to rejig the posts as only three attachments can be posted at a time so I couldn't simply add it without messing up the chronology. Still, it's an interesting and somewhat bizarre ammonite so was worth it.

that was shoddy Phil ! spit spot

Keef

I've had a tinker with the thread, hopefully it looks better and more interesting now. I still think these reconstructions should have ten arms, not the eight as they mostly depict, but there you go. No-one really knows either way.....

If anyone finds any good reconstructions, please drop us all a line in this thread!

Thanks in advance!

Phil

Here is a peculiar reconstruction

Nautiloid (http://www.besse.at/sms/evolutn.html)

Scroll down to the Birds section :shock:

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

very VERY curious !

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!

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.

The original orthoconic nautiloid! (http://www.geocities.co.jp/NatureLand/5218/tyukinnoserasu.html)

:lol:

:roll: Phil, some people have too much spare time;
still amazes me how you locate this stuff, just gifted I guess ! 8-)

Keef

Welldone Phill. The nautiloid illustrations are just amazing!

Thanks for putting this together

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?

PS, What is your avatar, I've been wondering?
It's "My uncle Cthulhu" :)
A 3d model by Fred Bastide. You can see the full rendering here:
http://www.texwelt.net/images/galleries/cthulhu_final_petit.jpg
I think it's quite funny, though at the moment I'm contemplating about switching it with one of those nautiloid illustrations!

:lol: :notworth:

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. (http://www.notam02.no/~oyvindha/graphics.html)

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:

Thanks ever so much for the picture Kevin. The endocones are really clear. I'm flabbergasted at exactly how wide the siphuncle is, I certainly did not expect to see that. All the pictures of the siphuncle I've seen in ammonoids tend to be much, much smaller in ratio to the diameter of the shell, so this was a surprise.

What an interesting solution to the problem of counterbalancing weight and bouyancy whilst maintaining stability.

Is it possible that the siphuncle was just a flat tissue like the siphuncular membrane of cuttlefish (it lies just ventral to the cuttlebone)? Then it would appear wide in a fossil.

See This Thread (http://www.tonmo.com/forums/showthread.php?t=3772) for some views of the shape and eccentric siphuncle position of endocerids.

Thank you for that, I learnt something significant, which doesn't happen every day! :thumbsup: :cheers:

Following the addition of Belemnotheutis, I have now updated all the entries to provide links to images of the species listed, and a few related research papers.

Phil, you've been a very busy boy!

I would just like to take this opportunity to thank you for all the hard work you do putting stuff like this together, I really appreciate it.

:notworth: :notworth: :notworth: :notworth: :notworth:

Cheers Kevin!

There may be better links out there to some of the species listed, so if you find any, please just shout and I'll add them.

Much appreciated.

Hi everyone,

Sorry for popping in to the thread this late, but......

Some sources say that aptychi are elaborate lids, while others say "jaw apparatus". By that word, are they actually parts of ammonite's beak, or even analogous to coleoid beaks?

I have seen that some of them (those preserved in place) are simply too big to the point almost blocking the living chamber - but not quite lids either. If they really are jaws, I think that would be pretty awkward (beside being scary) with jaw that big :hmm:

Thanks everyone !

-agha.]

I think the aptychi are generally believed to be the beak nowdays.

This issue was discussed in this old thread (http://www.tonmo.com/forums/showthread.php?t=627), a pic of radular teeth filling the body chamber of an ammonite to the apparent exclusion of any soft tissue, unfortunately the photos are missing, some of the same observations were made. :smile:

still no answers :wink:

hmmmmm, yeah, the subject itself is a great debate until now :hmm:

I wonder if this link (http://www.calfrye.com/aptychi/morphological_terminology.htm) actually says something. Sorry, but I find it rather difficult to understand. It even mentions crustacean carapaces as a possible identity of the aptychus. Why crustaceans ? :confused:

thanks,

-agha.]

hmmmmm, yeah, the subject itself is a great debate until now :hmm:

I wonder if this link (http://www.calfrye.com/aptychi/morphological_terminology.htm) actually says something. Sorry, but I find it rather difficult to understand. It even mentions crustacean carapaces as a possible identity of the aptychus. Why crustaceans ? :confused:

thanks,

-agha.]

One of those references (about crustaceans) is from 1882 - not that I am saying that the work isn't still relevant today, but maybe there is more information about aptychi today.

There are some small crustaceans (like ostracods) that have two paired "shells."

The following is from the Link (http://www.calfrye.com/aptychi/index.html) provided:

The principal purposes of this study are to examine and describe the "spathiocarids" of the Cleveland and Chagrin shales, investigate their relationships with similar Devonian taxa, and attempt to provide solid identification of their nature, if possible. This latter goal was not fully realized, but two of the most likely alternatives have been eliminated. It is probable that these fossils should be referred to the Cephalopoda.

It seems alot of thin carbonaceous films have been referred to Spathiocaris, a phyllocarid crustacean, and a few other taxa, but this report puts them in synonymy and refers them to 7 species of Sidetes Giebel, 1847, and interprets them as cephalopod jaw elements.

A few crustaceans have been found in fossil cephalopod shells, the radular teeth in the missing photo on the other thread looked like crab legs, so these all have to be taken into account. :grin:

I've just added Cameroceras. Not much info to go on out there in net-world so the details are a little vague I'm afraid.

Cameroceras looks like it was the ruler of the Ordovician sea.
Phil, did you add the figure used for scale or did it come with the reconstruction? Have you stopped using the London bus?

The figure was already there Kevin. If I'd made the image I would have used a London Transport bus conductor instead of a Japanese Manga warrior.

8-) A cool reconstruction from 1916 (from this (http://www.copyrightexpired.com/Heinrich_Harder/index.html) site, ...check out the funky diplodocus :wink:) These resemble most of the reconstructions I have seen in the last year or so, the artist may have been way ahead of his time (not).

I've just added Polyptychoceras. Not much info to go on as most of it seems to be restricted to Japanese websites and research papers one can't access for free.

I tried to keep the entries roughly chronological, but it's getting difficult to manage as sometimes they have to be inserted into a block which has reached it's image capacity.

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.

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


Actually, older nautiloids have been found with color-patterns surprisingly similar to modern Nautilus (don't ask me for details, I read this years ago). Coincidence? More likely that the group was very conservative. I'd bet the ammonoids were far less conservative, but have only heard of the one (early Triassic, Nevada) with color bands... was it Subvishnuites welteri? Preservation is all when it comes to color... the specimen must be original shell. Maybe some of those nice Pierre Shale, Fox Hills Sandstone, Hornby Island or southern Alberta specimens might respond to UV or other methods of checking for color patterns?

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.
Thanks!

The apparent "color pattern" on the Aturia is actually not. It is something to do with the shell structure; I have seen it on various Miocene specimens, and it can be seen to be the shell surface located between the septa. It may be due to translucence of the thinnest part of the shell allowing the matrix within to show through. None of the New Zealand Eocene or Oligocene specimens I have seen show this, but their preservation differs from the NZ Miocene ones.

:welcome: to TONMO

I thought I remembered that part of the lack of patterns was that the actual shell material is rarely preserved, but I know that occasionally even proteins in the shell have survived, which doesn't seem consistent with a loss of the shell patterning... hmmm...

Some sources say that aptychi are elaborate lids, while others say "jaw apparatus". By that word, are they actually parts of ammonite's beak, or even analogous to coleoid beaks?


Aptychi are found in Jurassic-and-later ammonoids. They are 2-piece and close the aperture nicely. Anaptychi are one-piece and are found in phylloceratids and Triassic-and-older ammonoids, and are the lower mandibles of these beasts. They may well fit over the aperture, with the tip against the early part of the whorl (where the "black band" in Nautilus ends). Whether they had a dual function (operculum and biting) I don't know.

:welcome: to TONMO

I thought I remembered that part of the lack of patterns was that the actual shell material is rarely preserved, but I know that occasionally even proteins in the shell have survived, which doesn't seem consistent with a loss of the shell patterning... hmmm...

Shell matter being recrystallized or replaced (or just dissolved and left as empty space) is common enough with ammonoids, but in some horizons the original shell is preserved (beautifully nacreous). I have been through my own collection and the local university's geology department, with both normal light and UV, and have found that a significant but small proportion of specimens of Cenozoic gastropods, all original shell, show at least faint hints of color-pattern, most only under UV. Some of the best examples were badly leached. But specimens of a single species from the same horizon at the same locality are inconsistent; one may show a pattern clearly and another partially or not at all. A student doing a master's has shown that the pattern is not organic, but some inorganic chemical which replaces the pigment or is a result of pigment breakdown.

I am a fossil preparator at the University of Otago, Dunedin, New Zealand. A few years ago I worked with an artist who was painting scenes from 4 periods for a major fossil display at the regional museum. One was a specimen of an Eocene Aturia cruising along. As the color-patterns (if any) of the members of the genus are unknown, I decided that spiral bands would be a nice contrast to its ancestor, Nautilus. There is one problem with reconstructing the animal of Aturia. If you look at a shell in good condition, you may not something that is never mentioned in the literature. Look at the growthlines. They tell you that either the shell has a huge hyponomic (siphonal) sinus or it has big lappets. I would say that it's the latter, as I doubt that it had a huge hyponome... unless it was the boy-racer of the Cenozoic nautiloids. This raises the question of eye location; there is no ocular sinus, so, unlike Nautilus, there is no hint in the shell as to where the eyes were located. In front of the lappets? Wierd. Behind? Above... on long stalks?

:welcome: to TONMO vw1,

Dieneroceras from the Triassic in Nevada have spiral color markings while paranannites and owenites have radial color bands. The radial bands may be explained much like the dark bands found on modern captive nautilus, see this paper (http://www.blackwell-synergy.com/doi/abs/10.1111/j.1475-4983.2007.00722.x).
The spiral color pattern seems to me at least to be an actual color pattern.

Some pictures of these Triassic ammonoids can be found in

Triassic ammonoids: A photographic journey
James F. Jenks, Justin A. Spielmann and Spencer G. Lucas
Pages 33–80 PDF (http://paleo.cortland.edu/globaltriassic/Bull40/08-Jenks%20et%20al%20(ammo%20comp).pdf)(30. 9 MB)

plate 1 for Dieneroceras, plate 3 for Paranannites.

The Treatise on Invertebrate Paleontology, Part K, Mollusca 3, Cephalopoda "Nautiloids" 1964, University of Kansas Press and Geological Society of America, has a page (K23) showing some of the color markings on fossil cephalopods.