Holes In Cephalopod

[Auspex]

So you're saying that the white thing in the middle is the nautiloid and that the dark object is something else?

As I see it, based on the images, that is a fair assessment.

If nothing else, dropping the nautiloid mindset may open the way to better speculation about the dark, holed object on the surface (which certainly seems organic).

[bbrosen]

Croc jaw maybe? the fist pic looks like a croc jaw with the teeth missing

[painshill]

The siphuncle is convincing enough, but I had another thought regarding the uncharacteristic exterior holes. This information comes from Bill Heimbrock on the “Dry Dredgers” website and the pictures below are his too. I don’t think he will mind me sharing them since he was looking for opinions on what he found.

He said he had heard that bryoza of the Spatiopora sp. are found encrusting straight-shelled cephalopods with their monticules aligned in the direction of the cephalopods’ travel and that such encrustation was likely in-vivo rather than post-mortem. The alignment was suggested as offering lower water-resistance.

The pictures above show a cephalopod specimen which he found encrusted on both sides with a Spatiopora sp. bryozoan. One side (second picture) is a partial cast of the cephalopod shell, with the bryozoan encrusting the inside structure but with the monticules still aligned in the direction of travel. The cephalopod was obviously dead when the shell infilled with silt, but did the bryozoan encrust the silty cast of the shell? Or was the bryozoan originally on the outside surface of the cephalopod shell when the animal was alive and continued to encrust the cast after the cephalopod was dead and the shell disintegrated?

Might we be looking at something similar here? A more-heavily bryozoan-encrusted cephalopod, either in-vivo or post-mortem, but with a bryozoan of a genus that has large zooid pores rather than small monticules?

[Tethys]

I have come up with an alternate explanation for this specimen. I think it is a Cretaceous species. There are small, rare, relict patches of Cretaceous strata in SE Minnesota, and it is an excellent match to some of the figures in this PDF. Subprionocyclus percarinatus on plate 15 looks nearly identical.

[BobWill]

I have come up with an alternate explanation for this specimen. I think it is a Cretaceous species. There are small, rare, relict patches of Cretaceous strata in SE Minnesota, and it is an excellent match to some of the figures in this PDF. Subprionocyclus percarinatus on plate 15 looks nearly identical.

Sorry, if you mean specimens 5 and 6 on plate 15 I don't see the resemblance at all.

[Ludwigia]

I have come up with an alternate explanation for this specimen. I think it is a Cretaceous species. There are small, rare, relict patches of Cretaceous strata in SE Minnesota, and it is an excellent match to some of the figures in this PDF. Subprionocyclus percarinatus on plate 15 looks nearly identical.

I agree with Bob. I'm sorry, but I think you're way off base with your assumption.

[Thescelosaurus]

There is an obscure fossil called Cylindrocoelia minnesotensis named for Decorah Shale specimens from Fountain and Minneapolis that seems relevant here. E. O. Ulrich, who described it back in 1889, thought it was a sponge. Another area specialist, Frederick Sardeson, thought instead it represented bored siphuncles of straight-shelled nautiloids; the hard parts rolled around for a while, got eroded, got bored, and so forth. Figures 1-3 on this plate represent this species; Figure 2 is particularly applicable.

[Ludwigia]

Sorry, but your link didn't bring a plate, but just a bit of printed word.

[John K]

There is an obscure fossil called Cylindrocoelia minnesotensis named for Decorah Shale specimens from Fountain and Minneapolis that seems relevant here. E. O. Ulrich, who described it back in 1889, thought it was a sponge. Another area specialist, Frederick Sardeson, thought instead it represented bored siphuncles of straight-shelled nautiloids; the hard parts rolled around for a while, got eroded, got bored, and so forth. Figures 1-3 on this plate represent this species; Figure 2 is particularly applicable.

it took a bit to transfer the image from the Google Book page, but here's what Thescelosaurus talking about:

I can definitely see this

[Ludwigia]

Thanks, John. I can see the possibility, but I'm still not quite convinced The cross section doesn't seem to fit, although it's hard to see any detail.

[painshill]

Although we only have three and a half holes to look at, what I'm seeing is a suggestion that they are aligned in a regular off-set pattern.

The end view of the half-hole (the top one in the above picture) very clearly shows it to be cup-shaped and smooth-walled, which is very odd if that's the original profile. Does anyone buy into the idea that it might have been dead ceph with a thick overgrowth of something else that had large pores. Bryozoan? Sponge even?

[John K]

Although we only have three and a half holes to look at, what I'm seeing is a suggestion that they are aligned in a regular off-set pattern.

post-15171-0-15337000-1406672354a.jpg

The end view of the half-hole (the top one in the above picture) very clearly shows it to be cup-shaped and smooth-walled, which is very odd if that's the original profile. Does anyone buy into the idea that it might have been dead ceph with a thick overgrowth of something else that had large pores. Bryozoan? Sponge even?

I could go along with this, tempered with the thought we're revisiting the same argument(s) outlined in Thescelosaurus's post: "E. O. Ulrich, who described it back in 1889, thought it was a sponge"

It's certainly a weird one.

[Herb]

I don't know what it is either but I don't think it is a ceph.