Head Scratcher

[Miocene_Mason]

Hello everyone!

 

I am going to share this rather confusing tooth. I found it under a section of cliff whose major tooth producer was likely Zone 12, definite Calvert Formation (which is early Miocene, creeping up on mid Miocene). It wasn’t found in situ, but the state of the tooth is almost perfect, leading me to believe it had worn out not long ago and likely not a trade tooth. Given this tooth without context, I would call it a Galeocerdo cuvier. But, given the context, this should be impossible, Cuvier are supposed to have arisen latest Miocene or early Pliocene. But this tooth is the spitting image of a G.

cuvier and exceeds the size of any G. aduncus I have seen. I’ve shown it to a few seasoned collectors, and they can’t think of one of this size either. I only know of one tooth which approaches it from this area, and it does share the cuvier look, and I’ve just asked the owner what he thinks. What do you guys make of this tooth? First gasps of cuvier or is this just what aduncus start to look like when they get massive?

 

Tooth dimesions:

slant height: between 1 and 1 1/10 in

Width: 9/10 in

 

I apologize for the lack of natural light. 

[Fossildude19]

@MarcoSr   @caldigger  @sixgill pete  @Al Dente

[caldigger]

Given the sharpness of root angle I would put it as a G. aduncus.

 

[Al Dente]

Your tooth is bigger than any aduncus that I have but is pretty small for a cuvier. I’m guessing it is an aduncus from a very large individual.

[Miocene_Mason]

7 hours ago, Fossildude19 said:

@MarcoSr    

His son Mel is the owner of the only comparable one I’ve seen, he said he was thinking they were transitionals

[MarcoSr]

3 hours ago, WhodamanHD said:

His son Mel is the owner of the only comparable one I’ve seen, he said he was thinking they were transitionals

 

Fossil and extant Galeocerdo cuvier teeth have compound serrations.  See the picture of the extant example below:

 

 

 

What I call transitional G. aduncus show compound serrations on the first couple of large distal serrations but not on the mesial serrations.  I think I see in the pictures compound serrations on at least the first large distal serration of your tooth.  Could you take a close-up picture of these large serrations or confirm compound serrations?  I think your tooth is a transitional G. aduncus.

 

Marco Sr.

[FossilDAWG]

I'm curious, what is a "trade tooth"?

 

Don

[Miocene_Mason]

1 hour ago, FossilDAWG said:

I'm curious, what is a "trade tooth"?

 

Don

Native American trade tooth, some were traded from states further south and dropped. This is how some Great white teeth got into the mix. 

[Miocene_Mason]

2 hours ago, MarcoSr said:

What I call transitional G. aduncus show compound serrations on the first couple of large distal serrations but not on the mesial serrations.  I think I see in the pictures compound serrations on at least the first large distal serration of your tooth.  Could you take a close-up picture of these large serrations or confirm compound serrations?  I think your tooth is a transitional G. aduncus.

 

Will do so later today

[MarcoSr]

3 hours ago, WhodamanHD said:

Will do so later today

 

I should have also asked you to check whether the mesial serrations had any compound serrations.

 

Marco Sr.

[Miocene_Mason]

2 hours ago, MarcoSr said:

 

I should have also asked you to check whether the mesial serrations had any compound serrations.

 

Marco Sr.

Definite serrations on the first three distal blades, crenellations on 4th and 5th. I do not see compound serrations on the medial side. Would this mean transitional? I apologize for the lack of photo, my scope died and my iPhone isn’t quite up to the task.

[MarcoSr]

2 hours ago, WhodamanHD said:

Definite serrations on the first three distal blades, crenellations on 4th and 5th. I do not see compound serrations on the medial side. Would this mean transitional? I apologize for the lack of photo, my scope died and my iPhone isn’t quite up to the task.

 

Since there aren't any mesial compound serrations your tooth isn't a G. cuvier.  The size of your tooth (slant height greater than 1 inch), three large distal compound serrations, and Calvert Formation makes me think transitional G. aduncus.  There is debate on whether aduncus is Galeocerdo or Physogaleus.  There is debate on whether the direct ancestor of G. cuvier is mayumbensis or aduncus.  I believe that aduncus is the direct ancester based upon the Miocene teeth that I see in Virginia and that mayumbensis was a warm water Galeocerdo variant that went extinct.

 

Marco Sr.

[Miocene_Mason]

32 minutes ago, MarcoSr said:

 

Since there aren't any mesial compound serrations your tooth isn't a G. cuvier.  The size of your tooth (slant height greater than 1 inch), three large distal compound serrations, and Calvert Formation makes me think transitional G. aduncus.  There is debate on whether aduncus is Galeocerdo or Physogaleus.  There is debate on whether the direct ancestor of G. cuvier is mayumbensis or aduncus.  I believe that aduncus is the direct ancester based upon the Miocene teeth that I see in Virginia and that mayumbensis was a warm water Galeocerdo variant that went extinct.

 

Marco Sr.

Seems like a research opportunity for someone. I can’t find any literature on transitional G. aduncus. Perhaps they are too rare. Intriguing stuff.