Pennsylvanian Shark Cartilage? Brownwood, Texas

[Cantab91]

Help with details and ID please -

Went out with DPS to Brownwood, Texas this past weekend - Pennsylvanian - Missourian and Virgilian Stages. Had a great time - found my first 2 trilobites so I was doing the happy dance. Found a very small 1/2 inch piece of what I thought was coral because of the unusual pattern at Wilson's Clay Pit. Filed it with my corals for that day. The next day we hunted a road cut that seemed to be older material than Wilson's. Found three more larger chunks of this - 1 1/4 inches, 2 5/8 inches and 3 inches wide that had the same unusual pattern and some curvature. Still thought it was a coral. Before we went home, took one of the chunks to an expert to ask what it was and he said that it was Shark Cartilage. When I got home, looked at all of the pieces under a microscope - they are the same stuff. Anyone know more details? Don't have a good camera (dropped it in the Trinity on a previous trip) so this is from my iPad.

[Bullsnake]

The two middle pictures, in the second row, look like crusher shark tooth to me.

I've found a few (Deltodus, Campodus, and Sandalodus) with that texture.

I learned that diagnostic from Missourian. Check out his Pennsylvanian shark teeth thread.

http://www.thefossilforum.com/index.php?/topic/27428-some-pennsylvanian-shark-teeth/?hl=%2Bpennsylvanian+%2Bshark+%2Bteeth

[Cantab91]

Those photo's are just close ups of the two larger pieces. The magnification is about 20X. So is this a part of the palate with lots of very small crusher teeth?

[Bullsnake]

This is an example of what I based my 'best guess' on.

I will concede to your expert's analysis, though.

Really cool find, btw!

Closer shot:

Even closer:

[BobWill]

OK since I found out your pieces actually fit together I can't wait to see pictures of them assembled. I'll settle for a picture of them just laying in place, no need for the glue yet

[Missourian]

For comparison, some shark cartilage:

Fin:

Jaw:

Cranium?:

The honeycomb-like structure superficially resembles that of certain crusher teeth.

[Missourian]

A close-up of the fin shows a variety of appearance of cartilage:

Around Kansas City, at least, cartilage is limited to carbonaceous and phosphatic deposits.

[Cantab91]

Reply from Dr. John Maisey

Hello Kerri,

Many thanks for your e-mail and photos. I agree with the identification, this is calcified cartilage from some kind of shark. My best guess, based on the relatively featureless, flat surface, and the slightly sigmoidal cross-section, is that it is a piece of lower jaw cartilage. From the cross section, the cartilage appears to have several layers of tesserae (tiny individual calcifications forming each layer), which (along with the size of the fragment) indicates an adult individual, possibly a big ctenacanth shark.

I suspect that there are a lot more bits of shark cartilage in the Texas Carboniferous. Right now I have some pieces that were kindly donated by other collectors there, of the back ends of two really huge braincases (things were bigger in Texas, even in the Carboniferous!) I should have the description finished soon and hope to get it published, maybe in JVP. I suspect that these big sharks had Cladodus teeth, as some pretty big ones have been found there.

If you go back to that site, it would be very worthwhile to poke around and see if there are other cartilage fragments. Congratulations, you are one of the few paleontologists who can now recognize fossilized shark cartilage! (even many pro's don't have a clue). If only more people knew what to look for...

Best wishes

John Maisey

[BobWill]

Yea! If Dr. John says it's cartilage, it's a good ID. Very exciting to hear his descriptions of Texas mega-sharks is close to done.

[fossilized6s]

Wow!!! Such great info from such a small chunk of "whatsit". Awesome on the confirmation, congrats! Now get back out there, it's Dr's orders.

Edited August 26, 2014 by fossilized6s

[RyanNREMTP]

Very cool.