Triangular, Tapering Bone(?).

[Fossiholic]

Found recently on Edisto Beach, where Miocene and Holocene marine fossils are found mixed in with Pleistocene land vertebrate specimens.

Would like to know what this piece is.

[Auspex]

It has the look of a hyperostotic ("Tilly") fish bone.

[Al Dente]

It is a hyperostosed pterygiophore from a fish. The bone on the right of this picture shows a modern one found on the beach in Louisiana.

[RichW9090]

You're spot on, Al.

[Fossiholic]

Thanks for the feedback guys!

So now a few questions to further satisfy my desire to learn more:

Are the two smaller bones on the left "normal" pterygiophores? I found this sketch which indicates that pterygiphores are comprised of three parts, with the one looking most like mine being the "proximal" piece.

Are hyperotosed bones more apt to mineralize? What portions of fish tended to fossilize, and what didn't? I've seen plenty of posts of fish skulls, and the inner round section of vertebrae, but thought the rest was cartilage, and didn't fossilize. ???

Again, thanks for the quick ID, and the wealth of knowledge that you guys, and the other members of this awesome site provide. !!!

[Al Dente]

I found this sketch which indicates that pterygiphores are comprised of three parts, with the one looking most like mine being the "proximal" piece.

Are hyperotosed bones more apt to mineralize? What portions of fish tended to fossilize, and what didn't? I've seen plenty of posts of fish skulls, and the inner round section of vertebrae, but thought the rest was cartilage, and didn't fossilize. ???

Again, thanks for the quick ID, and the wealth of knowledge that you guys, and the other members of this awesome site provide. !!!

Different fish must have different number of pterygiphore parts. Before looking at the sketch you posted I had always assumed there was a single pterygiphore attached to each fin spine. I think all the fish bones are likely to fossilize but hyperostosed bones are more likely to be found because of their shape and size and they are less likely to break apart while tumbling around in the surf or stream bed.

[Indy]

Tilly on a catfish? spine Link

Specific identification of Tilly bones is a problem

because one must study fossilized fish with a Tilly in tact.

I know a few fossilized fish with Tilly bones have been found.

However, I can't recall any images of the fossil fish with Tilly bone(s).

Anyone know of any web images ??

Edited October 6, 2013 by Indy

[Fossiholic]

That's not a Tilly Indy . . . that's a super Tilly. Now I get it, and recognize the hyperostosis. And now that I've taken another look at mine, it's very obvious in that piece too. I hadn't even noticed the lack of symetry (in my fossil) caused by the hyperostosis until now. Much more obvious/exaggerated in the catfish bone.

Learned a lot through this find, and for that I am truly grateful. Also glad to have this piece to add to my ever growing collection.

[Indy]

Fossilholic ...

Want to see a Tilly that resembles a brain ??

Click Here

[Diceros]

I don't know if there's any point to commenting on a thread from 2013, but I'd like to correct some misinterpretations.

In the drawing Fossiholic refers to, several posters incorrectly wrote that the ptyerygiophore had three parts. In the drawing, only d, the bones below the fin are the pterygiophores. The elements above them are the dorsal fin rays (b & c) of the dorsal fin. The slender bones below the pterygiophores are the neural spines (a) of the vertebrae (e) of the bony fish's spine. By connecting the dorsal fins to the spine, the pterygiophores give the dorsal fins far better support.

By the way, the original large marine bony fish pterygiophore shown in the post, to me, doesn't look hyperostotic (having an extra lump of bone added) at all.

About fish vertebrae - sharks and ray (cartilagious fish, with no bones) vertebrae only calcify the circular or oval part below the spinal cord, the centrum, so that's the only part found as fossils (many have two holes in the top of the rim for the uncalcified cartilage of the neural arch, and two holes in the bottom for the haemal arch). Bony fish have bony skeletons, so their entire vertebra (neural arch, transverse processes, centrum, and haemal arch) can be preserved as fossils, if the environment of deposition isn't too rough. Fossils of shark vertebral centra can be easily distinguished from bony fish vertebrae.

[RichW9090]

I think sometimes we conflate hyperostic with pachyostotic. The bone in the OP, and the example Al Dente provided in the third post have a pachyostotic appearance to me - the bone is dense, shiny and enamel-like. Most Tilly bones are both pachyostotic and hyperostotic, but they are different things entirely.