Large Turtle Piece?

[Brandy Cole]

I found this partially covered in sand and very shallow water at the edge of a sandbar in a local stream.  I cleaned it up with vinegar and a toothbrush when I got home.  The fossils in the river near me are supposed to mostly be Pleistocene, but I've also heard that there may be some Cretaceous period marine fossils.  I tagged this as a possible turtle piece because that's what it resembled to me, but I couldn't really find anything like it when I searched the internet and this site.  

 

I have more pictures, including pictures from before I cleaned it, if those would be helpful.  It weighs about a pound.

 

Any information would be great.  Thank you!

 

--Brandy

 

[JohnJ]

A possibility and blast from our past...Link

[Brandy Cole]

19 minutes ago, JohnJ said:

A possibility and blast from our past...Link

Thank you for the quick reply.  It's nice to know I wasn't crazy for thinking it might be part of a turtle shell!  I was really excited that it seemed to be in such good condition, but I think that made it a little harder to find similar pictures. 

[Brandy Cole]

Not sure if this is the right place to ask, but I had a few more questions about this shell that are probably beginner level stuff.

 

On some posts about turtle/tortoise shells, I've seen discussions about 'predation marks' or teeth marks vs. regular disease or decay.  On the bottom/browner side of the shell (2nd picture toward the top), it looked to me like there were a few sets of teeth marks from two sharp teeth spaced pretty close together that bit down and scraped a few times.  Is that possible, or is there another more likely/benign explanation?  If they are bite marks, what type of animal may have done it?  

 

Also, one of the reasons I wondered if this was really a fossil at first was because it looked relatively shiny and natural colored.  I second guessed myself that it might be new, even though it was heavy and obviously rock.  Why would some fossils of the same types of animals look brittle and gray when others look more colorful and smooth?  I'm sure the material they're fossilized in plays a part, but does age play a part as well?  Is this fossil newer just because it looks newer?  Or is that deceptive?

[fossilus]

On 11/10/2020 at 6:01 PM, Brandy Cole said:

 

On some posts about turtle/tortoise shells, I've seen discussions about 'predation marks' or teeth marks vs. regular disease or decay.  On the bottom/browner side of the shell (2nd picture toward the top), it looked to me like there were a few sets of teeth marks from two sharp teeth spaced pretty close together that bit down and scraped a few times.  Is that possible, or is there another more likely/benign explanation?  If they are bite marks, what type of animal may have done it?  

 

Also, one of the reasons I wondered if this was really a fossil at first was because it looked relatively shiny and natural colored.  I second guessed myself that it might be new, even though it was heavy and obviously rock.  Why would some fossils of the same types of animals look brittle and gray when others look more colorful and smooth?  I'm sure the material they're fossilized in plays a part, but does age play a part as well?  Is this fossil newer just because it looks newer?  Or is that deceptive?

 

The holes on the darker side look like holes for blood vessels to me.

As to the color, that is generally determined by what type of soil the fossil is buried in along with any fluids/minerals that are present. Dark shales will generally result in darker fossils, clean sands maybe lighter fossils. 

I've found bones and teeth from extinct animals, in the river, that are black, brown, white and everything in between. 

[Brandy Cole]

On 11/10/2020 at 6:42 PM, fossilus said:

 

The holes on the darker side look like holes for blood vessels to me.

As to the color, that is generally determined by what type of soil the fossil is buried in along with any fluids/minerals that are present. Dark shales will generally result in darker fossils, clean sands maybe lighter fossils. 

I've found bones and teeth from extinct animals, in the river, that are black, brown, white and everything in between. 

Thank you, that helps explain why the fossils we find may be different colors.  Almost all the bones we've found so far have been very dark colored and thick.  On those, it's pretty easy to immediately tell they're fossils.  On the ones that are lighter in color, I doubt myself more.  I picked up a whiter jaw bone that was hard and sounded like fossil when I was out at the river, but when I got it home and tried to clean it with vinegar, it immediately started turning brown.  I read about trying a burn test, and it smelled like it burned, so that one fooled me.  I still have a lot to learn.  

 

I may not have explained the part of the shell I'm talking about very well in terms of the holes.   I'm attaching another picture, and I marked the spot I'm talking about in blue in case that makes a difference. 

 

Thank you.

 

[fossilus]

1 hour ago, Brandy Cole said:

Thank you, that helps explain why the fossils we find may be different colors.  Almost all the bones we've found so far have been very dark colored and thick.  On those, it's pretty easy to immediately tell they're fossils.  On the ones that are lighter in color, I doubt myself more.  I picked up a whiter jaw bone that was hard and sounded like fossil when I was out at the river, but when I got it home and tried to clean it with vinegar, it immediately started turning brown.  I read about trying a burn test, and it smelled like it burned, so that one fooled me.  I still have a lot to learn.  

 

I may not have explained the part of the shell I'm talking about very well in terms of the holes.   I'm attaching another picture, and I marked the spot I'm talking about in blue in case that makes a difference. 

 

Thank you.

 

 

Sounds like you are learning what it took me a long time to learn, determining which bones are fossilized is sometimes difficult. I have a llama jaw that looks like it was only a year in the river, and yet its 1000's of years old.

 

I still think that you are looking at holes for blood vessels.  Predation marks are not terribly common.

[Brandy Cole]

On 11/9/2020 at 9:20 PM, JohnJ said:

A possibility and blast from our past...Link

 

On 11/10/2020 at 10:02 PM, fossilus said:

 

Sounds like you are learning what it took me a long time to learn, determining which bones are fossilized is sometimes difficult. I have a llama jaw that looks like it was only a year in the river, and yet its 1000's of years old.

 

I still think that you are looking at holes for blood vessels.  Predation marks are not terribly common.

Thank you, I'll have to keep in mind not to disregard something just because it looks too clean!  :-)

 

Also, this piece has lightened up considerably after it dried out.  It lost most of its brown color now that it's been out of water several days.  

 

I figured predation marks may be a long shot because I've read that most turtle "predation" marks are probably due to illness or natural causes instead of predation.  I was just curious about this one because at least one of the holes looks like it has a big drag mark/scrape coming down from it into another hole.  If I had found a modern turtle marked this way, I'd assume that a gator or gar had bitten into it because of the angle of the holes and the scrapes.

 

I also thought that all the holes on the broken side of the piece (right side of pic) were those soft tissue/blood vessel holes inside that were exposed by the breakage, but I thought the holes toward the left were on the outside of the shell, not the inside.   So I may completely not understand what part of the turtle this would be.  Would this flat bottom part have been inside the turtle's body or outside?  What part of the turtle is it?  After looking at diagrams, my best guess was that it was a "peripheral" fragment from the carapace, but I have no real clue.  

 

--Brandy