The purpose of C. megalodon bourlette

[Miocene_Mason]

I’m having a senior moment. Someone asked me recently what the bourlette was for on a Meg. I responded it was a muscle attachment point, and I had heard some thought it allowed the meg to “flex” its teeth slightly to saw off chunks of flesh. They asked if I had a reference for that, and come I can’t find where I heard it from. It must have been a somewhat reputable source if I internalized it, unless my mind just made it up. Has anyone else heard this or found a source which says this? If not, does anyone know it’s true purpose? Thanks!

[Miocene_Mason]

@MarcoSr @Al Dente

[Coco]

Hi,

 

To my knowledge, in a current shark jaw, no teeth are connected to a muscular system. In my opinion the teeth are fixed in the gingival tissue of the jaws of selacians and the bourlette doesn't serve as a binding to any muscle.

 

Coco

[DPS Ammonite]

14 minutes ago, WhodamanHD said:

I’m having a senior moment. 

Senior moments while in your senior year in school don’t count. You can only have a senior moment once you are well past your senior year in college. 
 

I noticed that a Bourlette is also referred to as a dental band in the literature. Now the hard part; what is it’s purpose?

[Miocene_Mason]

Just now, DPS Ammonite said:

Senior moments while in your senior year in school don’t count. You can only have a senior moment once you are well past your senior year in college. 
 

I noticed that a Bourlette is also referred to as a dental band in the literature. Now the hard part; what is it’s purpose?

Fossil huntings aging me, too much info in too small a brain!! 

[DPS Ammonite]

It appears that shark teeth are attached to a flexible dental ligament (and not a muscle?) that allows the tooth to flex back and forth in at least one direction. 
 

https://nhmag.com/biomechanics/172103/when-the-shark-bites

 

Ramsay, Jason & Wilga, Cheryl. (2007). Morphology and mechanics of the teeth and jaws of white-spotted bamboo sharks (Chiloscyllium plagiosum). Journal of morphology. 268. 664-82. 10.1002/jmor.10530. 

 

https://www.researchgate.net/publication/6370083_Morphology_and_mechanics_of_the_teeth_and_jaws_of_white-spotted_bamboo_sharks_Chiloscyllium_plagiosum

[Miocene_Mason]

17 minutes ago, DPS Ammonite said:

It appears that shark teeth are attached to a flexible dental ligament (and not a muscle?) that allows the tooth to flex back and forth in at least one direction. 
 

https://nhmag.com/biomechanics/172103/when-the-shark-bites

 

Ramsay, Jason & Wilga, Cheryl. (2007). Morphology and mechanics of the teeth and jaws of white-spotted bamboo sharks (Chiloscyllium plagiosum). Journal of morphology. 268. 664-82. 10.1002/jmor.10530. 

 

https://www.researchgate.net/publication/6370083_Morphology_and_mechanics_of_the_teeth_and_jaws_of_white-spotted_bamboo_sharks_Chiloscyllium_plagiosum

Thank you! Followed that to this publication on Carcharhinids, though it’s a little ambiguous on the mechanisms behind it. 
 

“Although it is true that the teeth (both upper and lower) of many sharks are loosely enough attached to the
jaws that slight external pressure can displace them a little forward or backward, "hinging" on their basal connections to the jaw margins (pers. obs., both authors), there seems no mechanism within several carcharhinid species that we have studied (including
those reported herein) that can perform this.
Instead, it is possible that a longitudinal rotation of upper jaw cartilages can have the effect of erecting the teeth so as to bring them to a more vertical orientation relative to the prey, without actually tilting the teeth on the jaws themselves. Some of these observations suggest that, in full
jaw protrusion, the upper teeth appeared more erect than would be usual in a non-feeding shark.”

 

Link

[Miocene_Mason]

Apparently movement occurs in the ligaments of Carcharodon carcharias, Great White Shark:

”It is generally accepted that connective tissue binds the tooth base, its root, to the underlying tissue over the cartilage during the eruption phase of the tooth [5] [22] but the teeth still remain quite movable made possible due to a “band of fibres” [24] . Whenever a shark opens its mouth, especially during upper jaw eversion, its teeth are moved forward, enabled through an active motion of this connective tissue base [21] [25] [26] . Whenever an upper jaw is retracted, its teeth are also “pulled back” into a rather thick sheet of connective tissue, the dental ligament, consisting of three distinctive layers of varying thickness where the most basic one reflects the above mentioned elastic fibers that enable this teeth motion in the lingo-labial direction”

https://m.scirp.org/papers/86101

[MarcoSr]

20 hours ago, WhodamanHD said:

I’m having a senior moment. Someone asked me recently what the bourlette was for on a Meg. I responded it was a muscle attachment point, and I had heard some thought it allowed the meg to “flex” its teeth slightly to saw off chunks of flesh. They asked if I had a reference for that, and come I can’t find where I heard it from. It must have been a somewhat reputable source if I internalized it, unless my mind just made it up. Has anyone else heard this or found a source which says this? If not, does anyone know it’s true purpose? Thanks!

 

Truthfully, I've always thought that the bourlette was there from that part of the crown being under the gum line.  I never really thought of it as an attachment point to a flexible dental ligament.  To me, the bourlette was caused by being fixed in the gingival tissue of the jaw.  Like you, I'm not sure where I got that idea from.  I've thought that same thing for all of the other species of shark teeth that have a narrow band of thinner enamel on the crown up by the root.

 

Marco Sr.