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Help me ID some POC bones! (Reptile or Mammal?) + Bonuses


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Hello again forum! 


Remember that bucket “goodie bag” I took home from the torn up Post Oak Creek a few months ago? I finally went through it and found some excellent stuff! (Im actually wow’d with some of this stuff because I’m just an amateur!) Surprisingly- I found tons of other stuff that ARENT shark teeth for once! :P  I grabbed a 5 quart bucket and took a big shovel scoop of gravel/mud from various parts of the entrance of the creek where the construction was and some from the first sandbar. Im working on an educational frame display I might actually eventually donate (there IS a massive park being built there for tourism !) and wanted to label found bones correctly. You’d think because I come here SO often I’d be an expert at the finds here but I’m not a real paleontologist or biologist, just an outdoorsy lass who can find fossils and loves learning about ancient animals. I tried my best to ID some of these finds myself, however I just found myself stuck and not very confident with IDing these bones. Because there’s so many mammal remains found here as well I wanted to ask you guys for help- and give me pointers how to ID cretaceous reptile bone, fish bone, and mammal bones.  (Teach this woman to fish metaphorically. ) Unfortunately my bone finds are worn and some are tumbled fragments which make it harder for a novice like me. Any help appreciated, and happy to learn!

Post Oak Creek is in Sherman, Texas. Cretaceous, Eagle Ford and theres also “Ice Age” fossils and even more recent fossils found here too. Everything here I can confirm is fossilized and very much stone.


I also added in 3 bones from last trip than need ID’d plus a few other cool things. 

***I took a TON of pictures and have to load them on seperate posts-please be patient! I will add captions to them all as well so wait until I post “Done!” :D Sorry for super dry hands. 

The process! 





Of course I DID find lots of baby shark teeth for my crafts! I make little coin displays with them to trade for other fossils with my friends! Yes you can really find THAT many in just a BUCKET. POC still has plenty of sharks! I prefer the small ones over the big ones. 

Post Oak atm is being torn up! A park is being built, and they are making an official parking lot & ramp to access the creek. This means lots of stuff is being uncovered! 


Also I just wanted to show off my cute little crustacean friends. I love finding these! 


The Finds: all spread out! Ruler is in MM (milimeters). I labeled them by letters and there’s some bonus things in there to ID! 



These are the bones Im most curious about! (More photos below)



These are more recent fossils, I feel confident at least that G, I, & J are turtle shells. No idea about H or K but might also be turtle? M & L look and feel lighter but are still very much stone- maybe mammals. 


Someone already helped me ID that N and O are fragments of mammoth teeth but what the heck is P!? Could it be a pig tooth or even…human!? 


* Bonus Round! * 

?1 I think is the tiniest ptychodus tooth ever! I have no idea of the species however it’s probably one of the tony teeth in the outtermost bottom part of the jaw (the teenie long ones!) ?2 I think is some sort of spine? It almost reminds me of a belemnite or sea urchin spine. Its definitely organic and not man-made. ?3 I THINK I FOUND A NATIVE AMERICAN CLAY BEAD! 

I find a few of these every once in a while there, usually small. Are these little Cretaceous sponges? 



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I took most of these photos with my phone macro lense attachment, hoping this will help with ID’ing! 

(sorry for the gross dry hands!) 



A: So at first I think this could be a Cretaceous marine reptile, but turning it over it also reminds me of the underside of a turtle shell (plastron). It reminds me of the mosasaurus bones I found at NSR with the white minerals inside the “pores”. It was a cool find! I have a photo above of my finding it in my wash. 





B: I have no idea! It does feel Cretaceous “reptilian” but I could be dead wrong. 



My imagination of childish delight makes me think it looks like a stone alligator’s head in this picture! There was a tiny pebble stuck inside. 



C: When I saw this I had to look at it to make sure it wasnt petrified wood. It definitely looks like a bone! But is it a reptile or mammal? 






D: I was wondering of this is a big Cretaceous fish rib! Someone on here said Cretaceous fish bone looks “splintery” and this one has lots of shine to it! Almost iridescent. 




E: Not sure if this is a reptile, fish, or mammal. Very weighty for a small specimen. 


(Accidental picture of D posted out of order) 




F: I was wondering if this is another fish rib! Its very similar to D. 


Photo of B that was posted out of order:


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F: (continued) Hopefully this is fish bone and not a piece of pet wood!



H: ID UPDATE- turtle carapace! 

I have no idea who this belonged to! Its light colored, so maybe something more recent, but definitely stone. It sort of reminds me of a turtle? The “tooth” part is so bizzare! I’m desperate to know what this is! (Additional picture at bottom of my final post)


K: Is this a turtle femur? Its definitely fossilized to stone. I think this is a more recent freshwater turtle.







L: This is a big piece of bone, and much lighter that some of my other stuff for its size. Someone at the creek told me they think its “pig bone” and to chuck it. It’s definitely stone/fossilized. I have a gut feeling its a mammal of some sort. Thoughts? 




M: Someone also at the creek told me “pig bone” for this one. I actually found this sieving during my last trip. This almost looks mammalian. Thoughts? 






P: I’m dying to know if this is a human tooth. I know there’s mammals out there with human-like teeth and lots of wild pigs but this looks almost like a molar! Should I put it under my pillow and see if I get a quarter to rule out if its a human tooth or not? :P 








?1: ID UPDATE- Ptychotrydon tooth


So this is probably the smallest ptychodus ever!  Since I’m passionate and weirdly lucky about these shark finds I wanted to share! My spouse thinks its crazy I spotted that in the sieve because its SO tiny! It strikes me as one of the long tiny ones on the bottom outer part of the plate! If not-let me know! 





?2: I found this tiny cool thing! Its hallow and not a perfect cylinder. It’s definitely organic and not man-made! It sort of reminds me of a hollow belemnite (I have some larger orange clear ones from a river) but also possibly a broken sea urchin spine? Ive never tried to hunt for urchin spines but stumbled on this. Its got these “lines” or “etches” in the light that remind me of fingernail-like growth so it’s not perfectly smooth. 






?3: This was the coolest find in my bucket! A CLAY BEAD! It has to be! It’s definitely striking me as man-made and it looks like when I made clay beads in art class. The hole isnt perfect in diameter either, like a twig was used. The edges look imperfect like it was finger-rolled over a twig. SO COOL! I always donate my native american finds so Im trying to look up what tribe lived here and if there’s a way to give them part of their culture back.  :) 









DONE! Thanks to all who are reading this! It was a long post but hopefully my pictures were helpful enough. Please give me a walkthrough how to tell the difference between Cretaceous marine reptiles and mammal bone fossils (fish possible too if possible!) so I can help others in the creek! 


Photo of H posted out of order:


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3 hours ago, AmmoniteDelight said:

So this is probably the smallest ptychodus ever! 

More likely to be Ptychotrygon than Ptychodus.

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3 hours ago, AmmoniteDelight said:

So this is probably the smallest ptychodus ever!  Since I’m passionate and weirdly lucky about these shark finds I wanted to share! My spouse thinks its crazy I spotted that in the sieve because its SO tiny! It strikes me as one of the long tiny ones on the bottom outer part of the plate! If not-let me know! 

Agree with @Al Dente, it's Ptychotrygon, a sawskate, likely P. triangularis.


Most of the bone chunks are indeterminate; the ones with infilled porous bone are usually marine reptile, the ones that aren't infilled are usually much more recent mammals.

3 hours ago, AmmoniteDelight said:

H: I have no idea who this belonged to! Its light colored, so maybe something more recent, but definitely stone. It sort of reminds me of a turtle? The “tooth” part is so bizzare! I’m desperate to know what this is! (Additional picture at bottom of my final post)

This does look like part of a turtle's shell, if I'm not mistaken, I believe the "toothy" projection is part of a rib.


Glad your goodie bag is yielding some goodies. Be sure to sift it down to finer gravel size and use a magnifying glass (or microscope if you have one) - there are plenty of microfossils, even down to the scale of sand grains.

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Yes, H is part of a turtle carapace. It is the end of a pleural bone and the pointy part inserts into the peripheral bone at the edge of the shell. 

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Ooo thank you all so much! I will have to do some reading on ptychotrygon! :) It never crossed my mind it could be a skate, I’m learning! So fascinating. I will definitely have to get another bucket to bring home and see if I can find more of those! 


Glad to know that H is a turtle and that my instincts on it are correct. I can totally see it how! 

Im actually saving for a microscope and slides right now, uncanny! Ive always been SO curious about what kind of microfossils are there. 

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7 hours ago, Al Dente said:

More likely to be Ptychotrygon than Ptychodus.


6 hours ago, ThePhysicist said:

Agree with @Al Dente, it's Ptychotrygon, a sawskate, likely P. triangularis.

Thank you both SO much! After comparing it with pictures online thats 100% it! I think thats even cooler than a tiny ptychodus tooth and I feel confident labeling it as P. triangularis. I will definitely keep its shape on my radar next time Im fine sifting! I use a flour sieve for the finer stuff and thats how I even spotted it. :) 

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My 2 cents :


• P isn't a human tooth, we do not have such great roots or this form of tooth.


• What intrigues me about two is the facets, I don’t know what it is. The sea urchin spines are very rarely hollow, and those that are much finer.


Ptychotrygon is a skate while Ptychodus is a shark. Agree with what was said earlier.



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I think you have some neat finds here mixed in with several un-identifiable chunks of bone.  It may help to group these in smaller batches and make more than one post in the future.  Maybe it's just me. I'm just having a little trouble keeping track between the pictures of all the different items.

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