Sharktooth Hill shortfin mako?

[ScottM]

Despite several visits to Sharktooth Hill and hundreds of teeth, I've yet to confirm a shortfin mako (Isurus oxyrinchus or is it Isurus desori?). Perhaps this is a possible candidate. Or maybe another C. planus or C. hastalis lower. To me, the features that make this one look different from those other common STH teeth are that it is relatively long with a narrow base/wide root, and also that little bend at the tip when viewed from the side (I think it shows up in the bottom two pics ok). It just stuck out as "something different" and I was able to eliminate a lot of other possibilities. So maybe I got my first shortfin mako? Thanks for your help!

 

[sixgill pete]

I get more of an Isurus retroflexus (longfin mako) vibe from this tooth.

[siteseer]

Yes, I think that is an upper anterior tooth of Isurus oxyrinchus.  Depending on who you talk to, it's an early I. oxyrinchus or it's I. desori.  I'd have to read up on what the current consensus is on the acceptance of desori.  I oxyrinchus is uncommon in the STH Bonebed.  The lateral teeth are more difficult to differentiate because they can look like C. hastalis laterals especially the smaller teeth.

[siteseer]

19 hours ago, sixgill pete said:

I get more of an Isurus retroflexus (longfin mako) vibe from this tooth.

 

Hi Don,

 

It's possible but I'd expect a clear "elevated platform" of the root (labial face) that Kent noted in his Chesapeake sharks book - the inflated section at the crown/root boundary.  Also, Isurus retroflexus is so rare at STH that I doubted its existence there for years.  Bob Ernst found just one that I'm aware of and he dug there 300 days out of the year for at least 15 years on his property and another 15 years at other sites before that. 

 

Jess

 

[ScottM]

Thank you both, Jess and Don!