Help identify fossil.

[Gemdaddy1331]

This is in my buddy's backyard, we know nothing of the type of rock we are in Jefferson county, Missouri. We noticed this on the side of a bluff. I think it's a about 1meter  long vertebrae almost like an alligator or some kind of big lizzard like a komodo dragon though I don't know if or when alligators would have been in Missouri. Appreciate your time

[Kane]

Jefferson County is mostly Ordovician, so too old for lizards or alligators. This is most likely a nautiloid, would be my guess. 

 

 

[Fossildude19]

I agree, this is likely an orthocone nautiloid.

 

What you are seeing as vertebrae are actually called camerae.

 

[Mark Kmiecik]

Orthocone nautiloid is what came to my mind first also. Some of them grew to lengths of "Holy cow, that's big!" Google it and read the Wikipedia listing.