NJ shark teeth

[Petebeh]

Hi everyone,

 

I found a Cretolamna tooth that has subtle secondary cusplets in the Cretaceous streams of Monmouth county NJ. I was wondering if this is variation within appendiculata or suggestive of biauriculata maroccana. Any thoughts would be appreciated as always. I hope to take some better pictures soon. 

 

The tooth in question is on the left with a typical Cretolamna appendiculata on the right for comparison.

[sixgill pete]

Interesting. I think you may possibly have a C. maroccana. Lets see what @MarcoSr thinks.

[siteseer]

I have a tough time with a tooth like that.  The tooth overall has a classic C. appendiculata shape especially with the U-shaped basal margin of the root.  C. maroccana generally has a shallower basal margin, but I have seen some teeth with more of a U-shape Identified as maroccana just because of the extra lateral cusplet.  C. maroccana teeth always seem to be broader jaw position by jaw position with perhaps sharper cusplets.  That's just my impression there.  I would have to yield to Non-Remanie or some of the other longtime NJ/Cretaceous collectors on that point.

 

To me the extra cusplet wouldn't be an indicator of a separate species because I see the occasional cusplet on a Carcharodon hastalis or planus tooth though that might be apples vs. oranges that are 45 million years older.  It's certainly something to talk about.

 

Jess

[non-remanié]

Nice tooth!   I agree with Jess that overall the shape fits our common NJ "appendiculata" better.   But I have seen other teeth from Ramanessin that really do seem much more like solid biauriculata so its not unreasonable.   Your tooth is unusual and I would keep it separate but I wouldn't focus too much on what to call it because there's a lot of uncertainty regarding Cretalamna species.   Archaeolamna kopingensis here also sometimes has an extra set up cusplets on some laterals and posteriors.  

[MarcoSr]

20 hours ago, sixgill pete said:

Interesting. I think you may possibly have a C. maroccana. Lets see what @MarcoSr thinks.

 

For years Cretalamna (Cretolamna) appendiculata was used for the species (catch all) of Cretalamna from the Cretaceous to the Eocene.  Mikael Siverson then wrote several papers expanding the number of Cretalamna species from the Cretaceous.  Mikael Siverson also stated that he needed to further study Cretalamna from the Paleocene and Eocene.  I have a good number of Cretalamna from the Paleocene Aquia formation of MD.  I have a very small number that have a secondary smaller cusplet like the specimen in this post.  I don't know if these Cretalamna teeth with this extra smaller cusplet are from a different species or just a variant or position variant within the same species.  I don't know if the Paleocene teeth that I have are Cretalamna appendiculata.  An associated set of Cretalamna teeth that Kenshu Shimada had called Cretolamna appendiculata , Mikael Siverson called the holotype of a new Cretalamna species (I hope I am remembering this correctly because at the moment I can't locate Mikael Siverson's papers.  I had a hard drive crash and lost a bunch of my papers) .

 

Edit:  Below is a paper reference and link for one of Mikael Siverson's papers:

 

SIVERSON, M. & LINDGREN, J. & NEWBREY, M.G. & CEDERSTRÖM, P. & COOK, T.D. (2015)
Cenomanian–Campanian (Late Cretaceous) mid-palaeolatitude sharks of Cretalamna appendiculata type. Acta Palaeontologica Polonica, 60 (2): 339–384
DOI: 10.4202/app.2012.0137

 

 

Maybe Mikael Siverson  @MikaelS  can give his opinion on this tooth.

 

Marco Sr.

[The Jersey Devil]

C. biauriculata would have a much wider crown than that along with other features. This tooth is a variant of C. appendiculata.

[Petebeh]

Thanks for the interesting feedback! I didn't appreciate the uncertainty associated with the Cretalamna genus. I guess it's typical that biology isn't as clear cut as we usually try to make it. I'll definitely read that reference you cited, Marco Sr.