Florida Giant Tortoise Leg Spur Fossil?

[Bronzviking]

Hello Fossil Hunters,

I haven't been on in awhile and missed the interaction with this group. I recently found an unusual find at a Tampa Bay Beach in Florida. Looking at the shape I immediately thought I had a worn bone fossil vs a seashell cast. The top view of the spur measures 1 3/8" x 1". The base platform which resembles an osteoderm measures 1 1/4"x7/8". I checked my Florida Fossil book and it resembles a Giant Tortoise Leg Spur. What do you think?

[Bronzviking]

I've never seen a spur before so can you guys please take a look?

@Harry Pristis @PrehistoricFlorida @Shellseeker@Plantguy

[siteseer]

I think that is an osteoderm of a tortoise.  A spur would have a different articulation at its base.

 

 

[Shellseeker]

Here is a good thread to read:

http://www.thefossilforum.com/index.php?/topic/11901-peace-river/#entry136253

and another

http://www.thefossilforum.com/index.php?/topic/34807-foot-pads-spurs-and-tail-bones/

. 

There are both Giant Tortoise foot pads and Giant Tortoise leg spurs, referred to on both the internet, online, in reference books and on this forum.   Some of the dermal osteoderms on the legs of Hesperotstudo crassiscutata are relatively flat, some are pointy. Scientifically, they are all called Osteoderms. Some of my friends use the colloquial terms, and I do not correct them.

 

[Harry Pristis]

There are no tortoise "foot pads" -- that's a collector misconception.  Dermal osteoderm is redundant.

    I am not certain whether the object in question is from a tortoise or from a glyptothere, because the root (the part anchored in the skin) is relatively thick for a tortoise.  Further complicating the identification is the eroded condition of the cortex bone.  If I were forced to choose between the two, I think I'd opt for glyptothere.

 

 

Tortoise osteoderms v

[Al Dente]

It doesn’t look like bone to me. I think it is a bryozoan, possibly modern.  I see circular tubes in this view. 
 

 

[Rockwood]

53 minutes ago, Al Dente said:

It doesn’t look like bone to me. I think it is a bryozoan, possibly modern.  I see circular tubes in this view. 
 

I see the resemblance, but I don't think it follows through the rest of the views well. 

[Bronzviking]

10 hours ago, Shellseeker said:

Here is a good thread to read:

http://www.thefossilforum.com/index.php?/topic/11901-peace-river/#entry136253

and another

http://www.thefossilforum.com/index.php?/topic/34807-foot-pads-spurs-and-tail-bones/

. 

There are both Giant Tortoise foot pads and Giant Tortoise leg spurs, referred to on both the internet, online, in reference books and on this forum.   Some of the dermal osteoderms on the legs of Hesperotstudo crassiscutata are relatively flat, some are pointy. Scientifically, they are all called Osteoderms. Some of my friends use the colloquial terms, and I do not correct them.

 

Thanks Jack for the links. What is your opinion? Have you found any similar fossils to make a comparison?

[Bronzviking]

5 hours ago, Al Dente said:

It doesn’t look like bone to me. I think it is a bryozoan, possibly modern.  I see circular tubes in this view. 
 

 

Yes I did notice that spot. I read that Bryozoan requires solid substrata such as rocks or wood for attachment. So it's possible it attached to this worn bone since it's been rolling around  the ocean for 12000+ years.

[Rockwood]

Hydroxyapatite is a hexagonal crystal that displays some of the same characteristics in a petri dish as it does in living bone. It would seem reasonable to expect a degree of self organization in some areas of certain bones.

No ? 

[Bronzviking]

11 hours ago, Harry Pristis said:

There are no tortoise "foot pads" -- that's a collector misconception.  Dermal osteoderm is redundant.

    I am not certain whether the object in question is from a tortoise or from a glyptothere, because the root (the part anchored in the skin) is relatively thick for a tortoise.  Further complicating the identification is the eroded condition of the cortex bone.  If I were forced to choose between the two, I think I'd opt for glyptothere.

 

 

Tortoise osteoderms v

Thanks Harry! Either way it's an exciting find.

[Al Dente]

2 hours ago, Bronzviking said:

I read that Bryozoan requires solid substrata such as rocks or wood for attachment.

 

Looks like it is growing on a chunk of limestone.

 

 

 

 

[Rockwood]

[Shellseeker]

5 hours ago, Bronzviking said:

Thanks Jack for the links. What is your opinion? Have you found any similar fossils to make a comparison?

I just went out on my side porch and picked out some fossils, most of which I found in the last couple of weeks. Some of these look like yours in shape, like the little one lower right.  In the past, I have found some that have the exact shape and size of yours.  I would have called it a Giant Tortoise leg Spur.  However, @Al Dente has a very excellent point. The consistency and texture of your find seems wrong. I am wondering whether a light coat of coral or bryozoan colony has covered your leg spur. I am interested in whether the conversation will continue. I have little to offer beyond the fact it looks like a leg spur with a very odd texture.

 

[Al Dente]

Here’s a comparison of Bronzviking’s example with a Florida beach found bryozoan from this web site-https://www.iloveshelling.com/blog/2010/09/28/not-coral-not-shell/

 

 

[Rockwood]

6 hours ago, Al Dente said:

Looks like it is growing on a chunk of limestone.

Maybe the limestone represents a period when the encrustation was covered by a dead bryozoan rubble field, followed by more happy days. The jumbled zooecia causing the confusion to some degree ?

[Bronzviking]

7 hours ago, Al Dente said:

 

Looks like it is growing on a chunk of limestone.

 

 

 

 

I've been combing these beaches for 20 years and know limestone when I see it. This is Not limestone. Harry is an expert in Florida fossils and he says its very worn bone, possibly Glyptodon. I'm not going to argue with that ID.

[Harry Pristis]

I appreciate the vote of confidence, Bronzeviking; but, Al Dente has made a strong argument.  The more I look at it, the less confident I feel about the object being an osteoderm.  That only leaves bryozoan.  No question these little colonies occur in South Florida deposits.  Here some examples from the Peace River.

 

 

[Plantguy]

Cool intriguing find...

 

For what its worth I'm in the bryozoan ID camp now as well, as Al Dente pointed out initially and Harry just stated---but at first glance it sure does have a spur shape/characters to it.

 

I did also look earlier at this post and saw the discussion/arguments for both camps and wanted to go back and look at my tortoise material and bryozoans side by side to look for distinctions. That weathering makes it very subtle.

So, I'm working on uploading some closeup photos of a similar spur I have and its different boney patterns. They are similar to Harry's other osteoderm images...

 

More in a bit...///EDIT: Not happening tonight as I've run out of time..I want to cut one in half!! This is more of an exercise to satisfy my own curiosity as Al Dente and Harry have already got this sorted out for you. Maybe I can do that and photograph this weekend...

 

Edit 2: Was in the process of cutting one in half and dropped it but still got some perfect sections to examine. Shows the irregular pattern internally--Interesting to also see the radiating patterns in the base (1st photo on the left)...

 

Regards, Chris  

 

Edited March 24, 2021 by Plantguy
Added 1st and cross section photo

[Bronzviking]

On 3/22/2021 at 10:29 PM, Plantguy said:

Cool intriguing find...

 

For what its worth I'm in the bryozoan ID camp now as well, as Al Dente pointed out initially and Harry just stated---but at first glance it sure does have a spur shape/characters to it.

 

I did also look earlier at this post and saw the discussion/arguments for both camps and wanted to go back and look at my tortoise material and bryozoans side by side to look for distinctions. That weathering makes it very subtle.

So, I'm working on uploading some closeup photos of a similar spur I have and its different boney patterns. They are similar to Harry's other osteoderm images...

 

More in a bit...///EDIT: Not happening tonight as I've run out of time..I want to cut one in half!! This is more of an exercise to satisfy my own curiosity as Al Dente and Harry have already got this sorted out for you. Maybe I can do that and photograph this weekend...

 

Edit 2: Was in the process of cutting one in half and dropped it but still got some perfect sections to examine. Shows the irregular pattern internally--Interesting to also see the radiating patterns in the base (1st photo on the left)...

 

Regards, Chris  

 

That's pretty cool those internal pictures Chris, thanks for posting! Love how pointy your spur is. So is it possible that I have a spur fossil and it has bryozoan attached to it like Jack pointed out?

[Bronzviking]

I appreciate every bodies input and time and welcome anymore comments. I took a few more shots on top of my Glyptodon scute and adjusted lighting to see the pores more clearly. I don't know if this will alter the outcome or not?

 

 

 

Edited March 27, 2021 by Bronzviking
duplicate photo

[Plantguy]

Good photos! I still think the others have it right as a bryozoan and its been weathered/beaten up and now has a suggestive osteoderm shape..

 

Regards, Chris 

[Bronzviking]

On 3/27/2021 at 10:54 PM, Plantguy said:

Good photos! I still think the others have it right as a bryozoan and its been weathered/beaten up and now has a suggestive osteoderm shape..

 

Regards, Chris 

I was looking at my fossil seashell casts (see picture) and wondering if a seashell could cast in limestone, could a bone/osteoderm cast as well? Has anybody ever seen this before?

[Bronzviking]

On 4/11/2021 at 4:45 PM, Bronzviking said:

I was looking at my fossil seashell casts (see picture) and wondering if a seashell could cast in limestone, could a bone/osteoderm cast as well? Has anybody ever seen this before?

Hey Guys, Is this possible that a bone could cast in limestone since seashells can? @Harry Pristis @Plantguy @Shellseeker

[Harry Pristis]

Consider, all the fossil casts in your image are steinkerns -- internal casts of shells made of CaCo_3.  The casts were formed, then the shells dissolved away.  Bones do not present significant hollows to be filled, and they generally don't dissolve in the Florida limestone.

  An exception might be a braincast, more common elsewhere.  Braincasts are rare-to-nonexistent in Florida limestone, I believe, a weak analog to the common seashell cycle.