Trilobite ?

[larryw]

I am new to this hobby but have always been interested for most of my 68 years ! While wandering the beaches and roadside cuts on Manitoulin Island searching for fossils a month or so ago I came across several interesting finds including this one. This was found along a stretch of shoreline and it appears to be the Cephalon of some type of Trilobite ? I think it is the imprint / image of the actual creature itself not it's protective shell which may be lying upside down beside it ! During molting ? Could some of the more advanced collectors please confirm / comment on these pictures ? I can supply additional pics if required. Thanx !.   LW

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[FossilDAWG]

I don't see a trilobite there.  I do see a nautilod (fossil on the left) and a cross section through some sort of bivalved shell, likely a brachiopod but possibly a clam.

 

Don

[larryw]

5 minutes ago, FossilDAWG said:

I don't see a trilobite there.  I do see a nautilod (fossil on the left) and a cross section through some sort of bivalved shell, likely a brachiopod but possibly a clam.

 

Don

This is the knowledge that I want to here !

[DevonianDigger]

I agree, no trilobite, but nautiloid and bivalves. Neat piece!

[apcsak]

Maybe an ORTHOCERAS or a BACULITES. there is a small one on the last picture, very right side. 

[FossilDAWG]

On 10/23/2016 at 4:13 PM, apcsak said:

Maybe an ORTHOCERAS or a BACULITES. there is a small one on the last picture, very right side. 

Orthoceras is the genus name of a small group of Devonian nautiloids from the Baltic area.  A century ago the name was used for all straight-shelled nautiloids but that use is vastly out of date.  However it is still correct to use the term "orthoconic" as a descriptive adjective to indicate a "straight-shelled nautiloid".

 

Baculites is a genus of Upper Cretaceous heteromorphic ammonite with a straight shell, apart from an initial tiny coil.  It has a typical highly convoluted ammonitic suture line. 

 

Rocks exposed on Manitoulin Island are late Ordovician, including the Georgian Bay Formation, and a couple of Silurian formations.  There is no marine Cretaceous anywhere within almost 1,000 miles of Manitoulin.  On the other hand the Georgian Bay Formation has orthoconic nautiloids, the most common being Treptoceras.  Although the specimen is consistent with Treptoceras, one would have to see a number of other features, especially the siphuncle, to be confident of that ID.

 

Don