nautiloid(?) I bought at a fossil shop

[monty]

I was in Santa Monica the other day, so I looked for a fossil shop hallucigenia told me about: Jurassic Gallery - Dinosaur Fossil display Specimens for your Home

They had quite an impressive array of fossils of various sorts, including a lot of shelled cephs. Being in Santa Monica, their prices were a bit steeper than the rock seller at the Hilo farmer's market where I got my last fossils, but they made up for it in selection... and they had a few "grab bag" baskets of ammonites and pieces of slate/shale (?) with ammonite impressions (and one thing that looked like a jellyfish; I was wondering if it's some Cambrian thingie...)

Anyway, the guy who was there, Bobby, showed me one that was his "favorite ammonite" because it was cut right through the siphuncle, and is rather nice looking. Since I'm trying to learn a bit of the ID techniques, I was a bit mystified, since it looked a lot like a nautiloid to me. As it turns out, they're not terribly expert at IDing fossil cephs, since neither knew what a nautiloid is or how it differs from an ammonite, so I suspect I'm on the right track... anyway, I decided to buy it (probably unwise until I get a new job, but he suckered me in by discounting it because of my obvious enthusiasm...)

They didn't have any record of where the fossil came from, but they did have a book Ammonites and Other Cephalopods if the Pierre Seaway Identification Guide (by Larson, Jorgensen, Farrar, and Larson) which described some nautiloids found there, and the closest one seemed to be Rutrephoceras dekayi var. montanaensis but I didn't have much to go on... it certainly seems to have a lot of nautiloid characteristics: central siphuncle, smooth septa, apparently simple sutures (although they're not really visible) and no visible ornamentation. I think it's involute, but it's hard to tell.

Anyway, here's some pix, anyone want to take a guess, or tell me I've made a novice mistake?

 

[Architeuthoceras]

Looks like Eutrephoceras to me Monty. There are alot of nautiloids like that coming from Madagascar these days, so I would say it either came from there or the north central US. And I would say it was money well spent.

 

[monty]

Looks like Eutrephoceras to me Monty. There are alot of nautiloids like that coming from Madagascar these days, so I would say it either came from there or the north central US. And I would say it was money well spent.

That's reassuring... I have the impression that the shop really goes for the "rich Hollywood people who want really cool fossils for their living rooms" crowd, so I'm probably priced out of them usually (they had a nice heteromorph for >$2000, for example.) Some of their not-so-prepped stuff seemed quite reasonable, though, so I may get a one or two ammonites and practice my ID skills a bit... then again, it would be somehow more satisfying to dig my own, of course...

 

[cuttlegirl]

Nice nautiloid, looks like you caught the fossil bug...

 

[monty]

Nice nautiloid, looks like you caught the fossil bug...

thanks!

I'm certainly enjoying fooling around with fossils, but I really like coleoids and soft body parts, so I suspect I'm out of luck there... although those vampyromorph fossils someone posted a few months back were really nifty!

Still, I like having a few representative ammonites and nautiloids and nautilus shells, so when I'm yammering about cephalopods to houseguests I can say "see, the ancestral ones were shelled like this, and the animal would be here and probably had 10 limbs since that seems to be the basal configuration and..." and they can nod politely and think "I had no idea he was this weird..."

 

[cuttlegirl]

Still, I like having a few representative ammonites and nautiloids and nautilus shells, so when I'm yammering about cephalopods to houseguests I can say "see, the ancestral ones were shelled like this, and the animal would be here and probably had 10 limbs since that seems to be the basal configuration and..." and they can nod politely and think "I had no idea he was this weird..."

Nice to know that I'm not the only one who does that... You should have seen the looks I got when I was reading that paper on cephalopod development while watching the kids at the pool...

 

[hallucigenia]

"Looked like a jellyfish"?? What, and you didn't buy it? Now I'm going to have to go there and see if they still have it...

 

[monty]

"Looked like a jellyfish"?? What, and you didn't buy it? Now I'm going to have to go there and see if they still have it...

I seem to remember it being an unidentified radial splotch, and maybe rather expensive... And I don't know much about IDing non-ceph fossils (and I'm not so hot even on cephs, although I sometimes know an ammonite from a nautiloid from a hole in the ground...)

 

[Melissa]

Monty, I bought a fossil to match yours while I was in arid, landlocked, mountainous Tajikistan. I'll post a picture when I unpack tomorrow. I like the reminder that it was not always so dry and that the mountains weren't always above water.

Someone in the shop asked me about it as I was carrying the rock around, so I explained that it was a fossil of an animal (no identification offered) and he then explained it to everyone else in Russian. I think half the people there could not believe that central Asia was ever underwater. Monty would have had more to say and required a translator with scientific vocabulary. I didn't have any big words to use.

 

[monty]

Monty, I bought a fossil to match yours while I was in arid, landlocked, mountainous Tajikistan. I'll post a picture when I unpack tomorrow. I like the reminder that it was not always so dry and that the mountains weren't always above water.

Someone in the shop asked me about it as I was carrying the rock around, so I explained that it was a fossil of an animal (no identification offered) and he then explained it to everyone else in Russian. I think half the people there could not believe that central Asia was ever underwater. Monty would have had more to say and required a translator with scientific vocabulary. I didn't have any big words to use.

Cool, I'm looking forward to pictures. I might have had a bit to say, but that's really why I need to go have hallucigenia (or Kevin or Phil or any of the other "fossils and history" folks if they're ever in town) go to the fossil shop with me, to say "that's not a jellyfish, that's a..." and such.

I'm consistently amazed at how my expectations about what people do or don't know often don't match reality... I'd expect fossil shop proprietors to be second only to palaeontologists in arcane knowledge about fossils, but, at least for the weird subfield of cephalopods and possibly for other invertebrate fossils, I was shocked that I knew more than they seemed to. But still, I am also astounded how a lot of folks around TONMO can say "that looks like an upper cretaceous whosawhatsis magnificus from the walla-walla formation" while the best I can hope for is "that's a planispiral involute ammonite with complex sutures and no ornamentation" if I'm lucky.

to all you fossils & history folks, really. I'm just glad I've got access to all you folks' encyclopedic knowledge! to all the octopus ID experts, too, by the way. I may be OK at research and concept memory, but I am in awe of so many folks around here in this regard I feel silly to be called out... of course, I guess you just said I would have a lot to say and it would involve science jargon, and that I can probably admit to even if I don't know a whosawhatsis magnificus from a habeas corpus.

 

[Melissa]

Here are two blurry pictures fo a nautiloid fossil from Tajikistan. I'll try again someday when my hands are steady.

Too-much-coffee Melissa

 

[Melissa]

I have to echo Monty's laudatory post about our fossil fiends. Much as I have admired rocks in the past, I would never have noticed this without the education I've received from TONMOers, especially Phil, who made the fossils in the British Museum palpably relevant rather than simply history.

 

[Architeuthoceras]

Nice fossil Melissa, I believe it is an ammonite, just going by the expansion rate of the shell and the radial orientation of the septa (a simple septa cut in half would be crescentric).

 

[monty]

Nice fossil Melissa, I believe it is an ammonite, just going by the expansion rate of the shell and the radial orientation of the septa (a simple septa cut in half would be crescentric).

My first thought was "that has a very long body chamber, so it's probably an ammonite"-- in the spirit of learning from the fossil fiends: is that a good reaction, or just me showing my ignorance? (I didn't think about either of the criteria you did mention, Kevin, although that may have been part of my "that looks like an ammonite, but I'm not sure why" that preceded my "maybe 'cause of the long body chamber" thought.)

 

[Architeuthoceras]

My first thought was "that has a very long body chamber, so it's probably an ammonite"-- in the spirit of learning from the fossil fiends: is that a good reaction, or just me showing my ignorance? (I didn't think about either of the criteria you did mention, Kevin, although that may have been part of my "that looks like an ammonite, but I'm not sure why" that preceded my "maybe 'cause of the long body chamber" thought.)

The long body chamber is another sign that it is probably an ammonite, maybe that is why I notice the expansion rate, coiled nautiloids seem to have only a few whorls and a short (relatively) body chamber while ammonoids have many whorls with a long body chamber, there are always exceptions. The siphuncle also seems to be ventral which is another mark of ammonoids (if that is the siphuncle I see) of coarse there are always exceptions. The real test would be seeing prochoanitic septal necks on the siphuncle, but again, there are exceptions there too.

One of the fossil fiends being fiendish