The CAUSE of Pyramiding

DPtortiose

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The growth plates of the bone aren't aligned with the scutes, that is where I am having an issue putting it together.

I'm not aware that bone has growth plates, could perhaps explain a bit more what do you mean with this. I'm not totally sure I understand you correctly.

Exactly. That's why it isn't and can't be bone pressure, but scute pressure. The pyramiding follows the shape of the scute, not the shape of the bone.
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I'm suggesting the bone shapes the scute, if you look at the X-rays you'll see that that the scute isn't misformed, it isn't thicker in any placenor shows any signs of swelling. The bone however is misformed. If misshapen scutes would be the cause, I'd expect to see some misshapen keratin, but the keratin in the X-rays seems 'normal'. Perhaps we'd get a better view from photo's from actual bone/keratin rather then an x-ray.

Bone, especially in young, is EXTREMELY pliable and moldable. An extremely small downward pressure by the growth of new keratin that becomes stiffer on top forcing the growth more downward, would easily be enough to cause the bone to grow in that same direction. We see examples all the time, from the Mangbetu tribe reshaping infant girl's heads, to my grandson's corrective helmet. Orthodontics, leg braces, Ancient Asian foot binding. A root can lift concrete with cellular pressure, a mushroom can poke through and reshape asphalt as it emerges. And it explains why we see tortoises that have pyramiding stop kept in identical conditions as they get larger. Mine certainly did. Look at the photos Craig @Anyfoot provided. Although his pyramided redfoot is barely what I would call pyramided, it is growing slightly differently. And if we look closely at the scute growth we see the same differences I noticed with my Burmese about the characteristic of the growth we can see. A smooth growing tortoise seems to have upward bulges as the new keratin is laid down, while the more pyramided one has the new growth discernably flatter on top. I am presuming this is forcing the growth downward then as the scute retains its same thickness.

The scutes don't remain the same thickness, they maintain an homogeneousthickness across the scute. That means scutes do become thicker as an animal ages to my knowledge (a hatchling has thinner scutes compared to an adult animal). Besides the keratin in the center should be more hydrated then the keratin in the scutes (less hydration loss since their isn't a 'edge exposed to air) and therefore should have more growth. At least if hydration does cause an increased growth in the scute, which I doubt that it does.
 

Anyfoot

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The one thing that's not clicking for me is that as dptortoise says, they get thicker keratin with age, so when a tort gets fully grown it still carries on producing keratin.
If the new keratin does not start at the centre of the scute everytime what would happen when it's fully grown.
Why can't Mark's theory work with keratin starting from the centre of the keratin aswell. This is an old Brazilian I have. Not only is the carapace super thick, so is the plastron. Doesn't the plastron work on the same principle, the plastron gets hydrated internally and on the external face from walking over wet grasses etc, and it doesn't get dried out from the sun or heat source. I have some with rough plastrons too(looks like wood) have they been kept on too dry substrate I ask myself.
IMG_20160706_184626.jpg
 

WithLisa

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I'm not aware that bone has growth plates, could perhaps explain a bit more what do you mean with this. I'm not totally sure I understand you correctly.
Just like a skull, the shell has lots of sutures (which are the growth sites). I only have a turtle shell, but it's similar in tortoises:
20160712_205409.jpg
 

Anyfoot

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At first I thought keratin grow from the centre of the scute and tracked to the boarders, then mark suggested the next new growth comes from the end of the old growth.
Why would it not grow from the full area and where the scute joints are to fill with new keratin have to be moist to allow the keratin that is exposed to the open to be supple to fill the new boarder crevice.
This is the only way I can see a carapace getting thicker and thicker once fully grown.
IMG_20160712_202126.jpg
 

Anyfoot

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Forgot to add, is that pyramided x-ray confusing matters, and the reason for the porous bone structure is dietary. Lack of calcium maybe.
 

Markw84

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The epithelium is the layer between the keratin scute and the bone of the shell. That is the layer that is producing new scute material. It is covering the entire underside of the sute, but the addition of new keratin along the underside of the existing portion of the scute is extremely small compared to the growth at the seam. It adds very little to overall thickness over the life of the tortoise. A very little bit over time, but nothing compared to the new growth that is happening at the seams. Extreme wear indeed does expose bone in old tortoises. If you look at a tortoise shell and remove the scute, it is not that thick. The bone continues to grow, the scute adds extremely little new keratin. A quote from Highfield:
" Terrestrial tortoises use a different mode of keratin-cell deposition (epidermal proliferation). In this mode, new cells are predominantly deposited at the edges of the scutes, again building from the inside surface "

At the EDGE of the scutes building from the INSIDE surface. So what if drying too quickly makes the top of that edge surface stiffer? IT PUSHES DOWN!

And this from an article in the World Chelonian Trust Newsletter:
"Turtle scutes are essentially the epidermal layer. The scutes are composed of a hard layer of keratin covering the bony plates of the shell. Beneath each scute is a layer of germinal tissue, the epithelium, which produces new scute material (4). During periods of growth, a new layer of keratin is applied to the entire underside of each scute. The new layer is very thin under the center of the scute and thickens towards the edges. This material is soft and plastics, and as it reached the seam and protrudes past the edge of the scutes, it flows upward, forming the new, expanded edge of the scute. The new layer bonds with the old edge and eventually hardens in place. As the scute grows, so does the epithelial layer underlying it."

"...it protrudes past the edge of the scute, it flows UPWARD forming the new expanded edge..." We now know drying stiffens - so what happens to that upward flow????

PYRAMIDING IS CAUSED BY PRESSURE EXERTED BY NEW GROWTH AT THE EDGE OF THE SCUTE PUSHING DOWN. THIS HAPPENS WHEN DRY CONDITIONS CAUSE THE TOP OF THE NEW SCUTE MATERIAL TO STIFFEN EARLIER THAN NATURAL, FORCING THE NEW KERATIN GROWTH DOWNWARD AGAINST THE BONE.

What else fits all these real life observations?

The top of the scutes of pyramided, but otherwise healthy tortoises, is the same height as the top of the center of the scutes of a smooth tortoise. The "valley" is sunken.
New growth on a smooth tortoise swells up forming an new ridge as it fills in the growth seam - even with the top of the previous growth ring. New growth on a pyramided tortoise creates a flat, stepped appearance with the new growth flat at or beneath the center of the level of the previous growth "ring".
Many older tortoises are more resistant to pyramiding.
Young tortoises are most susceptible to pyramid.
Scute thickness does not increase in pyramided tortoises it is the same as a smooth tortoise. It simply follows the contour of the pyramid at uniform thickness.
In a healthy but pyramided tortoise, the Bone does not thicken at the center of a pyramided scute. It also is a fairly uniform thickness following the contour of the pyramid.


Smooth closeup.jpg
Pyramid closeup.jpg
Pyramided Radiated.jpg
Pyramided Chilensis.jpg
pyramided bone.jpg
 

Markw84

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I'm not aware that bone has growth plates, could perhaps explain a bit more what do you mean with this. I'm not totally sure I understand you correctly.


I'm suggesting the bone shapes the scute, if you look at the X-rays you'll see that that the scute isn't misformed, it isn't thicker in any placenor shows any signs of swelling. The bone however is misformed. If misshapen scutes would be the cause, I'd expect to see some misshapen keratin, but the keratin in the X-rays seems 'normal'. Perhaps we'd get a better view from photo's from actual bone/keratin rather then an x-ray.

I forgot to add to the above observations...
The pyramiding follows the shape of the scute exactly and does not follow the shape of the individual bones and their growth seams.
All I have on my computer is turtle bone vs scute, but it is basically the same. You can see how bones have no relation to scute layout.


Here is the bones of a turtle. Note where the growth seams would be.
Bones layout of turtle.jpg
Here is the scutes and their corresponding seams. Never align. Creates more strength.
Scute layout turtle.jpg
 

Anyfoot

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Just to make sure I'm understanding you correctly. Is it more like this assuming it's hydrated correctly.
IMG_20160712_225546.jpg
 

Markw84

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Just to make sure I'm understanding you correctly. Is it more like this assuming it's hydrated correctly.
View attachment 180097
Sort of... But nowhere near the right scale to see relationship. If your scute is the scale we want, the epithelium would be a single line, and the bone would be about 6x the size you show. Also the epithelial layer is a very thin living tissue layer that is a "germination" layer for the keratin. This creates keratin growth. But unlike aquatic turtles, the keratin adds maybe one or two cells thick along the bottom, and the growth then concentrates on the seam, where it build out and up from under that edge, as growth causes the seams to separate.
 

Anyfoot

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Sort of... But nowhere near the right scale to see relationship. If your scute is the scale we want, the epithelium would be a single line, and the bone would be about 6x the size you show. Also the epithelial layer is a very thin living tissue layer that is a "germination" layer for the keratin. This creates keratin growth. But unlike aquatic turtles, the keratin adds maybe one or two cells thick along the bottom, and the growth then concentrates on the seam, where it build out and up from under that edge, as growth causes the seams to separate.
Ha ha yes i didn't scale it, basically it's a layer of keratin with a wrap around to fill the seam. If it's to dry at that time the wrap around can't happen and forces bone growth down.
 

Anyfoot

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So if someone has a bunch of hatchlings and some are smoother than others even though it seems all are tret the same is it because they are all at slightly different stages of growing when hydrated. For example.
We soak or mist 10 torts but at the time of hydration 1 has the growth seems open and 9 don't. When we put them back under an artificial heat source, they all dry out to some degree. No harm done to the 9. But the 1 has just had its new keratin that's just about to fill the seem dried out.
That example would be the 2 opposite ends of the scale.
 

Markw84

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So if someone has a bunch of hatchlings and some are smoother than others even though it seems all are tret the same is it because they are all at slightly different stages of growing when hydrated. For example.
We soak or mist 10 torts but at the time of hydration 1 has the growth seems open and 9 don't. When we put them back under an artificial heat source, they all dry out to some degree. No harm done to the 9. But the 1 has just had its new keratin that's just about to fill the seem dried out.
That example would be the 2 opposite ends of the scale.
I think that could happen, especially if the growth happened to coincide with a hot spell, vs rainy period of higher humidity when outside, etc. However, don't discount when we are talking about the slighter version of pyramiding like yours - There is probably just a difference in the thickness or strength of the keratin, one tortoise to the next. Just as some are larger, darker, a bit more domed. As I said in an earlier post, some people have thin brittle fingernails, and others have thicker, stronger.
 

WithLisa

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I think that could happen, especially if the growth happened to coincide with a hot spell, vs rainy period of higher humidity when outside, etc. However, don't discount when we are talking about the slighter version of pyramiding like yours - There is probably just a difference in the thickness or strength of the keratin, one tortoise to the next. Just as some are larger, darker, a bit more domed. As I said in an earlier post, some people have thin brittle fingernails, and others have thicker, stronger.
I believe another important reason is different behaviour. Some like very humid hides, others prefer dryer places, some are shy and others bask more often.
Right from the beginning I knew which of my torts was going to be the smoothest.
 

Anyfoot

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I believe another important reason is different behaviour. Some like very humid hides, others prefer dryer places, some are shy and others bask more often.
Right from the beginning I knew which of my torts was going to be the smoothest.
Yes, and that's probably why there are some pyramided torts in the wild.
If a hatchling stays in shade until bone structure becomes set in, it's probably going to be smoothy. One that ventures into direct sunlight from time to time won't be.
 

Yvonne G

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I don't know if this pertains to the subject matter, but I thought you might be interested. This deformed leopard tortoise was 10 years old when it was given to me. Her shell is so pinched in on the sides that her legs didn't work right and she could hardly move them. I was able to keep her alive for almost a year. As you can see in the pictures, even though it's a bit blurry, the bone corresponds to the misshapen keratin:

deformed leopard a.jpg deformed leopard b.jpg
 

aneta

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My wife need to read this. She spoiled all our torts with too much food because she cannot bear the look on there face every time when they know she is coming near.

After so many arguments, now we feeding them three times a week.
wow 3 times a week ,thats not enough in my opinion ,I couldn't do that
 
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