Jacksboro cartilege?

[BobWill]

I found this yesterday at Lost Creek dam, Finis Shale member of the Graham Formation. The darker parts might be shark cartilage. Any ideas?

[Uncle Siphuncle]

Looks like prismatic structure to me.  Here's a piece of Pennsylvanian shark stuff from my collection for comparison.  Also, a shark/ray rostrum from the Campanian.

[BobWill]

Thanks Dan. This has a distinctive shape too. I just heard from Dr. John Maisey and he thinks it's either from a gill arch of a big shark or the pectoral girdle from a smaller shark. I'll see if he wants a hands-on look.

[Missourian]

I would say the regular, cellular structure does indicate cartilage.

[BobWill]

7 minutes ago, Missourian said:

I would say the regular, cellular structure does indicate cartilage.

Then you join Dan W. in some good company. I just sent it off to the nations leading Paleozoic shark expert. Dr. John Maisey is convinced too and asked if I would donate it to the American Museum of Natural History for their collection so it's now on it's way to Ney York. Not exactly an important fossil but he said it could help add to our knowledge by exposing "histological features that provide clues" about some little-known sharks. I'll pass along whatever he decides about the suggestions he offered in my other reply.

[Missourian]

For reference, some shark cartilage from Pennsylvanian phosphatic concretions....

 

 

[BobWill]

I heard from Dr. Maisey about the cartilage today. Below is a quote from his email. He was happy to add it to the museum collection.

 

"Yes, your piece of cartilage arrived and I was just looking at it under the microscope. I'm pretty sure now that it is from one of the gill arches; the process at one end looks like where it met the next element in the arch, and in cross section it is convex on one side and concave on the other. That is a characteristic of fish gill arches, because one arch fits in the groove on the one behind it (I think I have that the right way round!). The groove also deepens as it approaches the process, in order to accommodate the blood vessels as they pass around the joint. "

[ynot]

38 minutes ago, BobWill said:

I heard from Dr. Maisey about the cartilage today. Below is a quote from his email. He was happy to add it to the museum collection.

 

"Yes, your piece of cartilage arrived and I was just looking at it under the microscope. I'm pretty sure now that it is from one of the gill arches; the process at one end looks like where it met the next element in the arch, and in cross section it is convex on one side and concave on the other. That is a characteristic of fish gill arches, because one arch fits in the groove on the one behind it (I think I have that the right way round!). The groove also deepens as it approaches the process, in order to accommodate the blood vessels as they pass around the joint. "

WOW, What a great find!

Congratulations!

Nice that You donated it to the museum.

 

Tony