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Today's Mystery Find


PJ68

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If I'm correct the larger fossil is a sawfish rostral tooth root? What has me stumped is the second item.

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is this a section of jaw?

It's funny the first pic looks like a crab leg. Then the underside looks like fish material.

JP, does that wide spacing look right for a fish mandible?

~Charlie~

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The "jaw" might be a finger of a Hoploparia lobster claw. Also the "sawfish rostral tooth root" has the look of an Enchodus palatine fang to me. No idea on the "mystery item".

Don

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FossilDAWG - You're close on the T-shaped specimen: it's a fang of the sabre-toothed fish Enchodus petrosus Cope, 1874, but it's the lower (ant. dentary) fang (attached to a bit of the dentary), not the upper (palatine) fang.

I agree with PJ68 that it's a jaw frag. of a bony fish, and not a sm. lobster claw. A lobster claw wouldn't have the tiny row of lat. teeth that this rt. dentary jaw frag. has (also, it looks like bone, and not calcified chitin). You know, just for grins, PJ68, you might try to see if the narrow (ant.) end of the jaw frag. fits with one end of the dentary part of the lw. fang (stranger things have happened).

By the way, the specimen above the shiny Everglades quarter (nice as it is, a ruler would be easier to use for scale), is an isolated toothplate tooth of the pycnodont bony fish Anomoeodus latidens, seen in basal view.

On to the more obscure mystery item. It's two cylindrical shipworm (Fam. Teredinidae) boring fillings filled with phosphate. The V-shape's fortuitous - the little clams chew through driftwood parallel to the grain of the wood, to make it easier to bore, and two just came very close. The trace fossil name is Teredolites longissimus, and it's considered a feeding trace. There's a fuller discussion of the two main types of feeding and dwelling traces made by small boring clams here:

http://www.thefossilforum.com/index.php?/topic/54798-need-help-on-a-few-finds-from-yorktown-and-surry-va/

Generally, when you see Ter. lon. in the Lt. Cret., it's cylindrical borings (often with a rounded end) made in wood which was later phosphatized (permineralized with phosphate, like fluorapatite). These two, however, just have a coating of more phosphate, I don't know why. Frankly, there aren't that many common trace fossils in the NJ Cret., so they're worth knowing.

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Thank you for all the info Diceros! I made the mistake of comparing the one piece to a sawfish rostral I already had and just assumed it was the same just supersized :blush: I still have much to learn. Thanks again, Pete

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Thank you for all the info Diceros! I made the mistake of comparing the one piece to a sawfish rostral I already had and just assumed it was the same just supersized :blush: I still have much to learn. Thanks again, Pete

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It is a large Ischyrhiza rostral fragment. I think the first photo of it didn't show much detail but the other photos do.

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1. Enchodus tooth with jaw fragment

2.Ischyrhira (sawfish) rostral fragment. The free-matrix aspect of Big Brook fossils can make it tough to ID but it's definitely that.

3. Awesomeness! Really nice bony-fish jaw frag!

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Two small clarifications. First, you have to be careful calling a fossil, like this rostral denticle of Ischyrhiza mira, a "sawfish", because there are the true pristid sawfish of the Tertiary (and still swimming around today), and the extinct sclerorhynchid sawfish of the Lt. Cret. (which this is). Both have long rostra hardened by prismatic calcified cartilage, with rostral denticles either sitting on the edge of the rostrum or embedded in the edge (Fam. Pristidae), or just straddling the edge (Fam. Sclerorhynchidae). When you look at the top two photos, of the base of this rostral denticle (I refuse to call them teeth, because they aren't in the mouth - the true teeth of sclerorhynchids look entirely different), you can see that the top was on one side of the edge of the rostrum, and the bottom on the other. Which brings me to the second point, this is a rostral denticle, not a frag. of the rostrum itself. Only recently, partial I. mira rostra with associated rost. dents. have finally been found in both Ala. and Tenn.

Abyssunder - the FF Gallery is awesome.

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The last picture of a fish jaw section and it's properly from a Enchodus.

Tony
The Brooks Are Like A Box Of Chocolates,,,, You Never Know What You'll Find.

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