Jump to content
Sacha

Giant Tortois Osteoderm?

Recommended Posts

Sacha

I found the item on the right a couple years ago and wrote it off at the time as just a unique Giant Tortoise osteoderm. I'm having 2nd thoughts now that I've found another one yesterday when digging at Zolfo Springs. The newest one (on the left) is still wet so it shows what looks like a Fossa or a Facet on the underside more clearly than the one on the right. Both display (or would have displayed) a very definite ridge down the centerline. So, just a different osteoderm, or something different?

 

DSCF1600.thumb.jpg.e8bbdf4405c00421844ea99074dcca80.jpg

 

 

Share this post


Link to post
Share on other sites
Sacha

DSCF1601.thumb.jpg.18dd4f6fa15d353f696c9901caac3688.jpg

Share this post


Link to post
Share on other sites
Carl

Can we get a side view of both? The one on the left might be a mammal patella and the one on the right should be a tortoise osteoderm.

Share this post


Link to post
Share on other sites
JohnBrewer

I’m with Carl on the right, same as my tortoise osteoderms

Share this post


Link to post
Share on other sites
Sacha
20 hours ago, Carl said:

Can we get a side view of both? The one on the left might be a mammal patella and the one on the right should be a tortoise osteoderm.

 

I agree the item on the right has all the features of an osteoderm, except the weird ridge down the middle. I hadn't thought of the item on the left being a patella.

 

DSCF1604.thumb.jpg.4a60c7447faba3e25e1b8d7fe1976d89.jpg

Share this post


Link to post
Share on other sites
Carl

Hmmm... Still not sure about the one on the left. Patella for now.

Share this post


Link to post
Share on other sites
minnbuckeye

The ventral side looks patella like but the side view  looks too thick for a patella assuming some of it is missing on top?? Patella blend in with the anatomy of the knee as the tendons attach. This does not appear that way to me, though knowing anatomy of the animals that are fossilized in Florida could change my opinion.

Share this post


Link to post
Share on other sites
Shellseeker

Monday? I was also on the river maybe 10 miles north of you. Agree with others .. left is not turtle osterderm.

but I still think it might be a "foot" thingy.  -- footpad, hoofcore, something like that..

I have not seen similar. Maybe one for Richard.

Share this post


Link to post
Share on other sites
Sacha

Per Richard Hulbert:

 

"Most likely it is a sesamoid bone from a juvenile mammoth or mastodon."

Share this post


Link to post
Share on other sites
ynot
1 hour ago, Sacha said:

Per Richard Hulbert:

 

"Most likely it is a sesamoid bone from a juvenile mammoth or mastodon."

Turns out to be much better than a turtle scute.

Congratulations.

 

Wondering if the turtle scute could be from a snapping turtle.

Share this post


Link to post
Share on other sites
Plantguy

Nice finds John. You are making me wonder again. So if Richard says its a sesamoid mean foot bone does that rule out a patella immediately or he just cant tell which one without further examination? Got any idea? The reason I ask it that I had to look up what sesamoid means and wikipedia says its a bone embedded in a tendon or muscle...smooth surface allows tendons to slide over and the sesamoid acts like a pulley--that makes sense to me. But it also mentions that kneecaps are the 2nd largest sesamoid in our bodies. Would you happen to know if in mammoths sesamoid means foot bone only and no chance of patella? thanks. 

 

Again a cool find! 

 

Regards, Chris  

Share this post


Link to post
Share on other sites
Sacha

Hey Chris!

 

That's everything I got from Richard. He didn't mention anything about a foot though. That reference was from Jack and I don't think it applies. I assume it could be a patella, but can't find any pictures to compare to, other than ads for dog treats.

Share this post


Link to post
Share on other sites
Harry Pristis

I'd accept Hulbert's diagnosis of sesamoid.  Certainly, Chris is correct that a patella is a sesamoid; however, patellae are consistently shaped by the contiguous bones, thus they are diagnostic.  Not so with other sesamoids (perhaps with the exception of some pisiforms).  The other bone is definitely a giant tortoise osteoderm.

 

Here is a description taken from Palaeo-Electronica (March 2010) which divides mammal bones into two types:
 1. endochondral bones (which ossify directly from an embryonic cartilaginous precursor, often constrained by joints and articular surfaces). These would include all limb bones, for example, and,
 2. intermembranous bones which are less constrained. Some intermembranous bones, such as the kneecap (patella), are almost always ossified in adult mammals (with minor exceptions).
   Other intermembranous bones, known as sesamoids, occur only in areas where a tendon passes over a joint, and ossify in irregular and unpredictable patterns. Humans have only one sesamoid, the pisiform in the carpus.
 Sooo... How can a collector identify a sesamoid or patella when he's sifting gravel or checking another collector's discard pile? Sesamoids (particularly pisiforms) and patellae have articular facets, often two facets, on what may be an otherwise undistinguished lump of bone.  How can you identify them to species? ...You'll have to take 'em to the local museum where they may be able to help you.
 _________________________
Comparative Variability of
Intermembranous and Endochondral Bones in Pleistocene Mammals
Kristina R. Raymond and Donald R. Prothero
Palaeo-Electronica (March 2010)
 "The topic of intermembranous and endochondral bone growth, size and variability is one that is not commonly touched upon, except briefly in passing, in paleontological literature. Generally, intermembranous bones are measured and discussed as only a slightly relevant topic in regards to larger studies of species or interspecific variation and sexual size dimorphism.
 "Intermembranous bones form directly from the connective tissue late in embryological development and after birth through intramembranous ossification. Some intermembranous bones, such as the kneecap (patella), are almost always ossified in adult mammals (with minor exceptions).
 “Other intermembranous bones, known as sesamoids, occur only in areas where a tendon passes over a joint, and ossify in irregular and unpredictable patterns (Vickaryous and Olson 2007).
 "The number and shape of intermembranous bones vary greatly within the Mammalia, and are highly taxon-dependent. Humans have the patella and only one sesamoid (the pisiform) in the carpus.
 “In many mammals, such bones include the patella and large sesamoids in the manus and pes. In ungulates, on the other hand, the only [relatively] large intermembranous element is the patella. The sesamoids in the manus or pes are small nodular ossifications in the digital flexor tendons, both at the metapodial-phalangeal joint and the distal interphalangeal joint; suids have as many as 13 sesamoids in the manus alone."
 
Large sesamoid of sloth(?) showing a ligamental groove:
sesamoid_largeA.JPG.d8d48ec4b03d384d0f80aae6490d4851.JPG
 
sesamoid_largeD.JPG.00e3402ebf93e06d367d61d621a10cfd.JPG
 
 

patella_menoceras.JPG

patella_Teleoceras.JPG

 

Pisiforms:

sesimoidtrio.JPG.aa1a8759521d8c9edb8d359d893bc7e0.JPG

 

Patellae:

patellae.jpg

 

Share this post


Link to post
Share on other sites
Sacha
47 minutes ago, Harry Pristis said:

 

 Sooo... How can a collector identify a sesamoid or patella when he's sifting gravel or checking another collector's discard pile? Sesamoids (particularly pisiforms) and patellae have articular facets, often two facets, on what may be an otherwise undistinguished lump of bone. 

 

Oh man, I can't imagine how many of these I've tossed back. 

Share this post


Link to post
Share on other sites
Plantguy
On 4/20/2019 at 12:12 PM, Harry Pristis said:

I'd accept Hulbert's diagnosis of sesamoid.  Certainly, Chris is correct that a patella is a sesamoid; however, patellae are consistently shaped by the contiguous bones, thus they are diagnostic.  Not so with other sesamoids (perhaps with the exception of some pisiforms).  The other bone is definitely a giant tortoise osteoderm.

 

Here is a description taken from Palaeo-Electronica (March 2010) which divides mammal bones into two types:
 1. endochondral bones (which ossify directly from an embryonic cartilaginous precursor, often constrained by joints and articular surfaces). These would include all limb bones, for example, and,
 2. intermembranous bones which are less constrained. Some intermembranous bones, such as the kneecap (patella), are almost always ossified in adult mammals (with minor exceptions).
   Other intermembranous bones, known as sesamoids, occur only in areas where a tendon passes over a joint, and ossify in irregular and unpredictable patterns. Humans have only one sesamoid, the pisiform in the carpus.
 Sooo... How can a collector identify a sesamoid or patella when he's sifting gravel or checking another collector's discard pile? Sesamoids (particularly pisiforms) and patellae have articular facets, often two facets, on what may be an otherwise undistinguished lump of bone.  How can you identify them to species? ...You'll have to take 'em to the local museum where they may be able to help you.
 _________________________
Comparative Variability of
Intermembranous and Endochondral Bones in Pleistocene Mammals
Kristina R. Raymond and Donald R. Prothero
Palaeo-Electronica (March 2010)
 "The topic of intermembranous and endochondral bone growth, size and variability is one that is not commonly touched upon, except briefly in passing, in paleontological literature. Generally, intermembranous bones are measured and discussed as only a slightly relevant topic in regards to larger studies of species or interspecific variation and sexual size dimorphism.
 "Intermembranous bones form directly from the connective tissue late in embryological development and after birth through intramembranous ossification. Some intermembranous bones, such as the kneecap (patella), are almost always ossified in adult mammals (with minor exceptions).
 “Other intermembranous bones, known as sesamoids, occur only in areas where a tendon passes over a joint, and ossify in irregular and unpredictable patterns (Vickaryous and Olson 2007).
 "The number and shape of intermembranous bones vary greatly within the Mammalia, and are highly taxon-dependent. Humans have the patella and only one sesamoid (the pisiform) in the carpus.
 “In many mammals, such bones include the patella and large sesamoids in the manus and pes. In ungulates, on the other hand, the only [relatively] large intermembranous element is the patella. The sesamoids in the manus or pes are small nodular ossifications in the digital flexor tendons, both at the metapodial-phalangeal joint and the distal interphalangeal joint; suids have as many as 13 sesamoids in the manus alone."
 
Large sesamoid of sloth(?) showing a ligamental groove:
 
 
 
 
 

 

 

Thanks Harry for the clarification! You all know what you are talking about for sure-- I'm just at times waking up and trying to digest some of it!

On 4/20/2019 at 1:03 PM, Sacha said:

 

Oh man, I can't imagine how many of these I've tossed back. 

I dont want to hear that! LOL...

 

Thanks for the interesting thread you guys! 

Regards, Chris 

Share this post


Link to post
Share on other sites
minnbuckeye

 @Plantguy, @Sacha, @Harry Pristis, @ynot, @Shellseeker, @Carl    For those of you that are a bit confused by sesamoid bones or just wanting to learn more, watch this VALUABLE video!!!!!!!!!! You will come away an expert on sesamoid anatomy in only 4 minutes.

Ungulate Bone Tutorial Proximal & Distal Sesamoids Equine & Bovine ...https://www.youtube.com/watch?v=-IdY_VHQI2o 

 
 

Then once educated, and if one is interested in pisiform bones  in particular, here is a comparative paper. (Different sesamoids than the tutorial) Check out  page 50 thru 54.

Share this post


Link to post
Share on other sites
Harry Pristis

 

Thanks, Mike, for sharing your expertise with us confused ones.  Now that I am an expert on horse and cow sesamoids and deer and bear pisiforms, what else can there be to learn!  How about showing us your collection of fossil sesamoids, preferably those that are not included in the two papers you provided.

 

Sloth patella:

1patella_A.JPG.499de17f20ebd1a519c2f0205d46347e.JPG1patella_B.JPG.7f7e9a6d72d8982b001ac0ec0ba45352.JPG

 

horse_neohipparion_phalanges.JPG.a7acb1b28da413f64fdbea4e91d37f07.JPG

3mystery.JPG

3mysteryB.JPG

3mysteryC.JPG

Share this post


Link to post
Share on other sites
minnbuckeye

@Harry PristisWish I had found a few during my trips to Florida. Maybe I did and just called it a chunkasaurus! Beautiful Navicular Bone (sesamoid) example pictured above.

 

I have a funny story from 20 years ago. I injured my knee. Had x-rays taken at Mayo Clinic. The physician asked if the interns could be in the room. No problem with me. So the doctor was discussing my knee and presenting questions to the  interns. He pointed to two little bones on the back of my knee and asked  "what are these bones?" Everyone sat in silence and I couldn't help myself. I "screamed out" sesamoid bones, thinking how dumb can these doctors be. I was right on the diagnosis  but the physician explained to me that it was very uncommon to find sesamoids in the knee of a human! Less than 1 in 500. Maybe I have some equine blood in me from way back when. Maybe I am part centaur! Anyways, we all had a good laugh when I explained how I had  knowledge of sesamoids, a serious issue in equine medicine.

 

Mike

Share this post


Link to post
Share on other sites
Harry Pristis

 

You haven't been paying attention, Mike . . . Humans normally have sesamoids in their knees -- they are called patellae.

 

We don't deal with equine medicine here, so calling a "distal sesamoid" a "navicular" is confusing and inappropriate.  This is veterinarian shorthand -- a nickname for the bone based on nothing more than its perceived shape.

 

These are equus horse naviculars in paleobiology-speak, and they are not sesamoids:

 

horse_naviculars.JPG.7ae6e5c604066e85143f5150a3908887.JPG

 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Recently Browsing   0 members

    No registered users viewing this page.

×