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Strange Little Bone


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I found this tiny bone today on the Brazos River in SE Texas. It looks like a small phalanx, but one end comes to a flattened point and is much darker than the rest. Any help with id and an explanation for the weird end of the bone would be much appreciated.

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Ischyrhiza mira sawfish rostral tooth with the tip worn/broken off.

Edited by Boneman007
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Yeah, the dark tip looks tooth like, but the root looks like a toe bone. That's what threw me off. Most of what I find is pleistocene mammal material. Occasionally I get a cretaceous shark tooth that has washed down from older formations. Would this be more cretaceous in age?

Edited by garyc
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Ischyrhiza mira sawfish rostral tooth with the tip worn/broken off.

DOH!

It is so obvious once the idea is planted... :blush:

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Gary, does it look more like bone to you under magnification? I'm not convinced yet by it's similar shape to sawfish (but I'm no expert, either)...that's a long way for a Cretaceous tooth to travel and survive the blender of a couple hundred miles of gravel bars. Eocene teeth are more likely candidates for the others you've found. Higher res photos might help confirm an ID. Interesting find for sure.

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John, you're right about my other finds being eocene. I misspoke.

The root side of this looks very similar to pleistocene aged bones I find around here. The tooth side is very smooth, without the porosity of broken bones I usually find. I will try to get some better pics.

Edited by garyc
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Yes this is a sawfish rostral - very similar to ones found in the Big Brook / Ramanessin Area in NJ.

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Classic sawfish rostral root. We find them often in gmr.

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Uncle Siphuncle

as for ischyrhiza... i tend to find them ozan thru kemp/escondido fms.

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Per request, I am trying to provide some better photos. It's been pointed out to me that it's highly unlikely that I would find a cretaceous tooth in this area. Just trying to see if there are other ideas...

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Maybe an Eocene sawfish?

That would make more sense geologically.

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yeah, the whiskey bridge sight, Stone City Formation is eocene and is about 80 miles north as the crow flies. Not sure how many river miles that is. I've just never found one of these or heard of anyone finding one in "my" part of the river.

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Chas.,

The sawfishes of the Cretaceous died out at the end of the period. The Eocene sawfishes belong to the same family we see today. Their rostral spines don't branch out at the base and they don't have an enameloid cap (crown) as in Cretaceous forms.

I think it is an Ischyrhiza spine and it looks beat up enough to have tumbled a long way.

Jess

Maybe an Eocene sawfish?

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John Hamilton

I'm not aware of any Pristiophorus rostral teeth that large. The only specimen I have is is jusr under 7 mm in length.

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No, there are Cretaceous sawfishes (family Sclerorhynchidae) which died out. There are sawsharks (order Pristiophoriformes), which are actual sharks (unrelated to sawfishes) also appearing during the Cretaceous, and they have survived to the modern day. An unrelated family of sawfishes (Pristidae) appeared during the Early-Middle Eocene. Rostral spines have been found at the "Muddy Creek" site (Fisher-Sullivan site), the Ypresian-age phoshate layers of Morocco (I've seen some unusually large ones from there), Chandler Bridge Formation sites and many others.

Eocene Saw Shark?

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njfossilhunter

Ischyrhiza mira sawfish rostral tooth with the tip worn/broken off.

It sure is......I got dozens of them

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Even the ones from the Late Miocene/Early Pliocene of Chile (the largest Pristiophorus rostrals I've seen), which might reach that length, are not that wide.

Some Middle Miocene rostrals from Peru average around 10mm - same size range for specimens from the Early Miocene of California.

I'm not aware of any Pristiophorus rostral teeth that large. The only specimen I have is is jusr under 7 mm in length.

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I'm not trying to beat a dead horse, but I was asked to provide higher resolution pic. Here they are. I hope these help. So far it sounds like the consensus is leaning toward a cretaceous sawfish rostral tooth that has survived a couple hundred miles of tumbling down the Brazos from the nearest cretaceous formations.

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