Found in shale rock by Georgian Bay, Ontario Canada. I estimate around 450myo

[Redmania]

I dug this out of the shale rock beach by Georgian Bay, Ontario Canada, and I can't seem to identify this fossil. 450 myo. It seems to have a tail that would have been covered in overlapping shells, which turns into something that looks similar to an abdomen. Quarter for scale.

Edited April 17, 2017 by Redmania
Country and province.

[Peat Burns]

Hard to tell from photo, but maybe orthoconic nautiloid showing the siphuncle.

[Redmania]

4 minutes ago, Peat Burns said:

Hard to tell from photo, but maybe orthoconic nautiloid showing the siphuncle.

I think it must be something similar. Most nautiloids in the area however seem to be one consistent cylinder or cone shape. This starts as a cylinder with scales on top, and then branches into a larger abdomen (seen in the other photos)

[Peat Burns]

6 minutes ago, Redmania said:

I think it must be something similar. Most nautiloids in the area however seem to be one consistent cylinder or cone shape. This starts as a cylinder with scales on top, and then branches into a larger abdomen (seen in the other photos)

Oops.  Didn't see that there was more than 1 photo.  I'll takeep a look at the other three.

[Peat Burns]

@Redmania, after looking at the other photos, I'm more convinced it is a nautiloid.  Hopefully others will come along soon with their input.  Nice find, and welcome to the forum.

 

The constriction is the exposed siphuncle where the phragmacone and chambers are missing.

[Fossildude19]

@FossilDAWG

[Monica]

Hi there!

 

I'm pretty sure that it's an orthoconic nautiloid, with the thinner part being the siphuncle.  There is a very large species that can be found in the Georgian Bay Formation - it's Endoceras sp., with its full name likely Endoceras proteiforme.

 

Super-nice find, by the way!!!!!

 

Monica

 

 

[FossilDAWG]

As Monica says, it is an endocerid nautiloid, and Endoceras proetiforme is the most likely ID.  These nautiloids had a large siphuncle, an internal tube that ran the length of the shell, which is often the only part of the shell that is found.  Around this was a series of chambers, called camerae.  The camerae are filled with sediment and are missing from the middle of your specimen, which is why it looks as if it has an "abdomen" at the tail end.

 

The smaller orthocone nautloids that are commonly found in the Georgian Bay Formation are mainly Treptoceras crebriseptum.  These nautiloids have a much smaller, bead-like siphuncle.  In the black shale one often finds flattened orthoconic nautloids; these are often identified as Geisonoceras but actually belong to a diifferent genus, the name of which I can't recall and will have to look up.

 

Don

[doushantuo]

old,but useful?

[Redmania]

Thanks everyone who commented! I've learned a lot about the anatomy and scale of this animal because of you folks. It's great to finally put a name to the fossil: Endoceras proetiforme
 

[doushantuo]

E Proteiforme is in here

by a very famous name in Paleozoic molluscan paleontology of the US,enjoy!

[doushantuo]

Foerste:colour patterns on cephalopods&brachiopods