Tough one Kevin. I'm having trouble determining the structures symmetry (if it has any at all), exacerbated by focus/resolution problems. If it is a hook then it is almost certainly incomplete (no prize there). Whoever collected/photographed it (?Mike Everhart) must recollect and look for further material, hopefully series of them, hopefully some of which will be more complete (and more revealing).
I know of one squid type only (extant squid) that has a single hook on an arm (two hooks in total on the intact animal; all other suckers carry conventional sucker rings) .... tiz a 'secret squid' .... All other squid that possess hooks, with which I am familiar, possess many of them, in two rows, either along the arms or arming the tentacle clubs (this is not to say the fossil 'cephalopod' shared the same body plan). Nevertheless, if this structure was a hook, or part of a hook, then more than likely there'll be many more of them locked in that matrix.
My guess is that those are teeth, rather than hooks, perhaps "baby teeth" from a ray-finned animal equipped with plate-like, crushing teeth. At first, I thought they might be dermal denticles (in part because of their small size), but most denticles I've seen have a flared ring around the base.
oceansofkansas.com has some photos of Ptychodus teeth, here:
You are correct, the webmaster of that site has changed the content of that page, it used to show a small "glob" of something that really didn't resemble anything, he thought it might be a squid hook. Those small teeth look alot more like hooks than the "glob" ever did! Sorry for the confusion.
The Peachnet.edu site notes that many of the fossils shown are "floor tiles" from Atlanta's Fernbank Museum. If those tiles are castings from the originals (seems likely: wouldn't want to tromp on the real thing), that could explain the mysterious reversal of the image Kevin provided.
It was not really the picture being reversed I was worried about; it was why one site had Acanthoteuthis listed as a belemnite and another site as a squid. Obviously they both could not be right.
After having done a little digging around (pardon the pun), it transpires that strictly neither is correct, depending on how pedantic one wants to be with the terminology. Acanthoteuthis appears to be a member of an obscure extinct order of coeloids known as belemnoteuthida which existed from the mid-Carboniferous to the Cretaceous(?). Despite the name, it seems that were a completely seperate order from the belemnites and were distinguished by a well-developed phragmacone and a very thin and delicate guard. With the belemnites the phragmacone is apparantly much shorter but the guard much more robust.
I'm sure it's much clearer with a diagram!
Other members of this order were Phragmoteuthis from the Triassic and Belemnoteuthis from the Jurassic and Cretaceous.
With many internet sources, including many fossil shops, confusing belemnites with squids and with an order name of belemnoteuthidae, it's no wonder there is some confusion! It certainly had me scratching my head.
Since I'm not really qualified to worry about species designations, I left that issue alone, wondering instead if the reversed image (produced as a "female" mold of the original fossil) might have led the good people at peachtree.edu to mis-label their "fossil." I sometimes drop in on various millitary aviation sites, where reversed photographs can lead fellow enthusiasts to believe that they've found a "new" variant of an aircraft: supercharger intakes on the starboard side of a nacelle become port-side intakes, and the next thing you know, someone's found a long-lost prototype. Happens a lot, even in books.
The TOL page refers the picture to a Belemnoid not a Belemnite, a Belemnite (Order Belemnitida) is a Belemnoid as are Belemnoteuthids. alot like the difference between a Ammonite and an Ammonoid. An Ammonite (Orders like Lytoceratida, Ammonitida, and Phyloceratida) is an Ammonoid (members of the ?Subclass Ammonoidea) as are Goniatites (Order Goniatitida) and Ceratites (Order Ceratitida). But I am only confusing myself, so I will leave taxonomy to the toxonomists
have the latest (several) classification of coleoids and nautiloids, and a nit-picking page (I knew I read that before). I guess if there were more than just empty shells to study classification would be more stable.
I've just read the debate...most interesting . I have not got a clue what it is, but it is flipping big to be a belemnite hook if you ask me, and too rounded. Still, I am probably wrong as usual. Anyone have any opinions?
i have alot of hooks from belemnites that i have found here in peterborough. they are hard to keep complete but they are rare aswell. let me know if you would like a link to see 1 of mine that i have for sale on my website. but i dont want to advertise it i just want to show it.