Shark tooth Meg or Carcharocles chubutensis

[RescueMJ]

Inland Venice, FL. First guess was Meg. Many others found in 100 yards of this one. Someone suggested :  Carcharocles chubutensis most fossils are Pleistocene in the area. The angle of the tooth is not like most megs I find here. Advice welcomed.
- Michael

[Thomas.Dodson]

Meg. The angle and shape suggests a later lateral series upper tooth.

[Praefectus]

Beautiful tooth. I also think it is a megalodon. 

[RescueMJ]

Thank you for the info. 
 

-Michael

[digit]

C. chubutensis ("chubs") are known for the small semi-attached side cusps and generally smaller size than C. megalodon which, current theory suggests, evolved from it. The predecessors in this chronospecies are C. auriculatus and C. angustidens (and possibly more intermediates depending on which other stops along the way you recognize).

 

 

https://en.wikipedia.org/wiki/Megalodon#Evolution

 

 

https://www.tandfonline.com/doi/full/10.1080/02724634.2018.1546732

 

Within the final species (C. megalodon) there is quite a bit of variation in shape and slant between younger individuals and older ones and between the different tooth positions for a single individual. It's really the loss of the side cusps and the transition to larger size shark (and teeth) that vary through time. Chubs are (mostly) a little too old for Florida (especially further down the peninsula). They were already transitioning into megs at the time of our exposures. There is a phenomenon called atavism where features that are lost through evolutionary change can reappear. Ernst Haeckel is noted for the phrase "ontogeny recapitulates phylogeny" which is fun to memorize and toss out (though largely discredited these days).

 

https://en.wikipedia.org/wiki/Recapitulation_theory

 

The underlying concept is that as an organism develops (ontogeny) it passes through and "recreates" (recapitulates) the stages of evolutionary history of the species (phylogeny). An example usually cited is that a human embryo passes through a stage where we effectively have gill structures and at some point have quite a robust tail. This applies to the mega-toothed sharks in a subtle way--some smaller megs can often be seen to have what appear to be signs of weak side cusps. They only have these when they are young individuals and they grow out of this atavistic feature once they are more fully grown. Of course, chubs are smaller in size than megs (increased size is the other change over time along with the disappearance of the side cusps) so when smaller teeth with faint side cusps are found in South Florida it gets people to wondering if they are "baby megs" or evidence of chubs. All of this confusion and room for discussion made possible by the cartilaginous nature of shark skeletons where the teeth (and occasional calcified vertebrae) are the only surviving elements left to use to describe species and infer evolutionary trends. Think of how much more difficult it would be to determine human evolution if all we had were isolated teeth.

 

 

Curious as to what the last two (seemingly unrelated) images in your post are doing there? Where these dropped in accidentally or is the highlighted conglomerate associated with the meg tooth somehow?

 

 

Cheers.

 

-Ken

[RescueMJ]

Thanks a lot for the info. Much appreciated.

-Michael

[BellamyBlake]

I'd say Meg

[RescueMJ]

Agree. Thanks. 

[PrehistoricWonders]

I’d go with meg.

[1foolishcaribou]

On 1/24/2021 at 10:08 AM, digit said:

Curious as to what the last two (seemingly unrelated) images in your post are doing there? Where these dropped in accidentally or is the highlighted conglomerate associated with the meg tooth somehow?

Hey Ken, those last two images are mine, but I have no idea how they got there. The other day I "started a new topic" with description and the photos. Now I can't find my "new topic" but found the photos here. (fossil photo migration?)  If I may, the story behind the photos is: central Washington County, northeastern Oklahoma, Pennsylvanian I believe. Very solid matrix, can't clean it any further safely. About 1/8" thick. Core appears different, as if hollow at some time or something. Tooth or seed shape in appearance. But not serrated like a shark tooth.

[digit]

9 hours ago, 1foolishcaribou said:

Tooth or seed shape in appearance.

Hard to see from just one angle in the images but it seems like it might be an internal mold of a bivalve mollusk--what is known as a steinkern or "seed stone". No idea how those images got into this topic unless you were writing multiple topics simultaneously (the forum software often does not like that).

 

 

Cheers.

 

-Ken

[1foolishcaribou]

Thank you. I can't imagine what kind of mollusk it may have come from. It actually tapers off as it disappears into the rock. I will try to come up with better pictures. The automatic camera I have really has only one setting: blurry. (It was a gift so I don't complain... out loud. haha)  I wasn't doing multiple topics BUT that doesn't mean I didn't do it wrong. I'm very tech ignorant. I will try again.  

[digit]

You'll get the hang of the forum software before long.

 

 

Cheers.

 

-Ken

[RescueMJ]

What’s really funny is “I was asking for a friend”. A 12 year old student didn’t believe my Meg answer. “True story.”