Is This A Nautilaidea Cephalopod?

[Magicman]

Today's find was this pyritized fossil (see attachment). Sorry about the colour, it's a nice golden colour but shows silvery in the phote. The size is 3" in length and 1/2 inch wide.

Question: Is it unusual to find the fleshy parts preserved like they are in this fossil?

Bob

[JustPlainPetrified]

I am thinking more of a crinoid.

[Auspex]

...Question: Is it unusual to find the fleshy parts preserved like they are in this fossil?...

To what fleshy parts are you referring?

[mikeymig]

Looks like a straight shelled cephalopod or nautiloid. I find pyritized (Devonian) specimens here in NY.

mikey

[caldigger]

I believe he is seeing the left side of the fossil as being tentacles and thus that being the soft tissue issue.

[Magicman]

Thanks Mikey, I found a good description of it in GB07 - Geology and Fossils, Craigleith Area, Ontario on page 36. It's classified as Geisonoceras tenuistriatum, a Nautiloid. This piece was found on the shores of Lake Ontario.

Auspex, the straight spiral cone comprises the rightmost two inches. The leftmost inch appears to be the fleshy tentacles. I have read that finding the fleshy material fossilized is not common but I'm not sure how uncommon. Is this a real find or somewhat common?

Thanks

Bob

[Auspex]

I think what we see is the crushed remains of the shell's living chamber:

[FossilDAWG]

Where was this specimen collected, and what is the age?

I see no "fleshy parts". The pyrite is eroded from the living chamber, leaving streaks of pyrite in parts. And yes it is a nautiloid cephalopod.

Don

[Magicman]

I found it today on the shores of Lake Ontario, south of Courtice, Ontario. This is part of the Whitby Formation which dates to about 450 million years ago.

The pyrite shell is the right side of the specimen. To the left is what I believe might be the fleshy tentacles, simply because it matches the artist sketches that were on several sites I visited today.

From searching on how fossils are pyritized, it seems that soft tissue can be preserved because the process occurs quickly. From a geolgical POV, pyrite doesn't leach.It's too hard once formed.

Thanks again all,

Bob

[Jeffrey P]

I'm also thinking straight-shelled nautiloid. The top portion (left) I think is a crushed portion of the shell. The pieces just don't don't look like tentacles. Cephalopod shells, by the way, are composed of aragonite which is more fragile than other shell material and thus more subject to crushing. I rarely find cephalopod shells that aren't flattened. Yours looks like a fairly typical example. Congratulations on a great find.

[Tethys]

"The pyrite shell is the right side of the specimen. To the left is what I believe might be the fleshy tentacles, simply because it matches the artist sketches that were on several sites I visited today."

I"m sure there is a technical term for this, I call it priming. I start seeing fossil crinoids everywhere if I spend a lot of time researching them. If there was soft tissue preservation, I would expect it to be a different in color and texture from preserved shell. It is a nice fossil nautiloid shell, but I don't see any preserved soft tissues.

"From searching on how fossils are pyritized, it seems that soft tissue can be preserved because the process occurs quickly. From a geolgical POV, pyrite doesn't leach.It's too hard once formed."

Iron pyrite is formed of iron and sulfur. In the presence of oxygen and water, it does oxidize and leach. Pyrite oxidized to sandy rust by slightly acidic groundwater is (sadly) a common component of my local geology. (Cambrian/Ordovician) It can also have a microbial component, the science is quite fascinating.

Leaching of pyrite by acidophilic bacteria.

[bethk]

Gorgeous find, regardless! I've found lots of Ordovician cephalopods on the shores of Georgian Bay near Owen Sound and Collingwood, but they're grey and dull (the layer they're in is the Georgian Bay Formation, which is slightly higher up than the Whitby Shale). Need to go south and east to see some of these golden treasures! Thanks for the pic.

[Wrangellian]

I would concur with everyone else.. Whether pyrite leaches or not, it does erode like any other rock (and worse: see 'pyrite disease'!), and this simple erosion accounts for the bits left of the living chamber which just happen to be reminiscent of tentacles. Nice find, anyway.

[MarqusandDad]

Remember right now you are the one with this in hand and excited about finding it, that leads to all kind of things running through the mind. As to your question about soft tissue, yes if what is on the left is soft tissue it would be more rare to find as most soft tissue is destroyed in the natural decomposition process which happens very fast as compared to the fossilization process of the hard surfaces.

[Magicman]

Thank you all.

The picture doesn't do the specimen justice. The shell is 2 inches long and a half inch wide with a 1/16 th inch rise at the highest point. The left side is 1 Inch in length and rises about 3/64" above the matrix at the shell and gradulally thins until the leftmost 1/8" inch of what appears to be the longest tentacle is almost flat with the shale matrix. I'm tempted to use a touch of HydroChloride acid on the pyrite to bring back the silvery finish but I really don't want to do anything to the piece.

It was a thrilling find. We found a few other pyritized fossils at the same location but there's a lot of shale that must be removed to expose the entire tribolites and one that looks like a starfish.

Bob

PS: Yes, pyrite can decay and crumble and the Canadian pyrite almost always does over many years. Some very hard pyrites (from Spain for example) seem to last forever. But pyrite that has leached does not reform into a solid pyrite structure, it becomes granular when leached by bacteria that comsume the sulfur or when sulpuric acid is formed as a byproduct of oxidiation leaving rust granules. The "fleshy" left side is solid pyrite, not affected by leaching yet (and I hope with a little advice on preservation from the geologists/paleontogists at the Royal Ontario Museum, it may last for a few more years.).

Edited April 21, 2014 by Magicman

[Pumpkinhead]

That is a definitely a straight shelled nautiloid. As for the fleshy part in the left hand side, it is possible that that could be the soft parts of the nautiloid. I've only seen that once before though in a display at the ROM. That kind of preservation with soft parts is very rare.

[Wrangellian]

That is a definitely a straight shelled nautiloid. As for the fleshy part in the left hand side, it is possible that that could be the soft parts of the nautiloid. I've only seen that once before though in a display at the ROM. That kind of preservation with soft parts is very rare.

Were the fleshy parts in that one preserved in pyrite, or something else?

[Auspex]

This is the crushed living chamber; note the tell-tale septa in the shell to the right of it, running right up to it. The tentacles would not have been in the living chamber, as the body would be there. Any tentacles, if present, would be well left of this area.

[jpc]

I agree with auspex. Cephalopods like this are made of a bunch of short segments piled on top of each other, as we see in the right half of your specimen, all the way up to the potential tentacles. Then, stacked on top of these is a much larger living chamber. The living chamber is generally more delicate (less structurally sound) so it often gets crushed, and I think that is what we are seeing here. Maybe with partial pyritization, which is also common in pyritized fossils.

[Magicman]

Thank you for the information. My son is studying to become a geologist but we have found a lot of fossils while rockhounding and prospecting. His interest in paleontogy is growing. It's nice to have options.