Hastalis or Isurus sp.?

[Largemouth Bass]

From the pits at the Aurora Fossil Museum. 2.5" slant height.

[Thomas.Dodson]

Looks like C. hastalis to me.

[Shellseeker]

Nice Tooth,  very large..  

I have been calling this one Hastalis for 5 years... It is the only one like this that I have ever found.

[hemipristis]

2 hours ago, Largemouth Bass said:

From the pits at the Aurora Fossil Museum. 2.5" slant height.

I would lean Isurus due to the relative narrowness of the blade relative to length

[jikohr]

1 minute ago, hemipristis said:

I would lean Isurus due to the relative narrowness of the blade relative to length

Do Isurus teeth get that big?

[hemipristis]

1 minute ago, jikohr said:

Do Isurus teeth get that big?

Yes, though it is uncommon

[hemipristis]

Alas the spoil piles… I miss them

Edited November 4, 2023 by hemipristis

[Largemouth Bass]

Thanks for the input. I'm also leaning Isurus sp. based on these images of Lee Creek mako teeth from Elasmo and J-elasmo. Bill Heim notes that I. oxyrinchus teeth broaden and look more like Carcharodon sp. teeth as they increase in size, so that may be the case with this tooth since it is large.  

[Fin Lover]

I also thought Isurus but, since everyone else had said hastalis at that point, I decided not to say anything. 

[Shellseeker]

12 hours ago, hemipristis said:

I would lean Isurus due to the relative narrowness of the blade relative to length

So you can see I labeled the Mako I found in 2018 Carcharodon hastalis. 

 

I looked that up and found this Wikipedia site

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

with this photo from some place called the Smithsonian and Note the label "Isurus Hastalis" 

 

It is an interesting question.  How do we differentiate between Isurus and Hastalis?  Not sure I want an answer.

[cck]

I think lower Hastalis are often mistaken for Isurus.. that may be the case here. Doesn’t seem to have that quirky sideways curve that Isurus often has. But of course there are gray areas …

[Fin Lover]

7 hours ago, Shellseeker said:

Note the label "Isurus Hastalis"

Jack, I believe that hastalis was changed from Isurus to Carcharodon because they decided that hastalis was more likely in the Great White lineage instead of Isurus.  You may also see Cosmopolitodus hastalis as a different form of hastalis.

 

 

[Fin Lover]

Also, here is the difference between C. hastalis and makos:

 

Fossil teeth of Isurus oxyrinchus, the shortfin mako shark, are common in Florida only on the northeast Atlantic coast (Duval and Nassau counties). Like Carcharodon hastalis teeth, they do not have serrated cutting edges, but differ in their much narrower, more curved crowns and longer root lobes (Kent, 1994).

From https://www.floridamuseum.ufl.edu/florida-vertebrate-fossils/species/carcharodon-hastalis/

 

[cck]

For example I’d call all these Hastalis, and they share many characteristics of the tooth in question 

[cck]

I’d love to hear some more discussion on this.. I’m still not clear what diagnostic features are employed to distinguish these two when the morphology is so close…