Tiny Meg or wishful thinking?

[siteseer]

43 minutes ago, sixgill pete said:

Jess, I agree that the top two left teeth are probably not C. limbatus and they do look like C. brachyurus. The bottom row, quite honestly could be from a number of Carcharhinus species and one of them could be Negaprion in my opinion. I have not seen them listed as part of the STH fauna, but the extant species is known from the Pacific coast of northern South America, Central America and Mexico including the Baja California area. I have the book that Doren is using as a reference, a signed copy actually. I use it as a reference, but rarely for identification.

 

No one has really worked on the Carcharhinus teeth from STH.  A friend once went through his collection and separated them into groups.  He saw teeth that resembled C. brachyurus and a couple of teeth that look like C. obscurus.  Broad-crowned Carcharhinus teeth like that are very rare in the bonebed.   He didn't name the other teeth but sorted them into uppers and lowers and then into groups like "finely-serrated crowns with coarsely-serrated heels."

 

Jess

[sixgill pete]

@siteseer @caldigger @Desert_survivor

After doing some more research, I think this tooth could be Carcharhinus priscus. According to 

"A Selachian Fauna From The Trent Formation, Lower Miocene (Aquatanian) of Eastern North Carolina" ; Gerard R. Case 1980

C. priscus, had a similar geographical range as Negaprion and ranged from the Late Eocene to the Middle Miocene. Look at plate 6, figures 6a and b and 7 a and b.

 

Know we now the Trent Formation (which has been renamed the Riverbend Formation) is early Oligocene. The location where the teeth from this paper were found is no longer available; a marina and completely overgrown along the man made canal. The Riverbend is exposed in a few other areas here in eastern N.C. It is possible I may have a similar tooth in my Riverbend teeth. I will have to look. 

As far as the Carcharhinus lineage, I agree that it could have descended from Abdounia. 

[verydeadthings]

The tooth is pretty similar to C. brachyurus, I'm attaching three upper dentitions for comparison. I take back my suggestion of C. albimarginatus, the shape of the base of the crown and the lateral notch is much different, I really am rusty  .  It's perhaps better to use fossil names for early Oligocene carcharhinid teeth, but it's still interesting to compare the fossil teeth with modern species. I don't have an opinion on the correct fossil species name, I'm not familiar enough with the literature.

[Desert_survivor]

Thanks everyone, for the incredibly detailed information and academic discourse. It was my pleasure to read through each of your responses.

[Paleoc]

On 11/15/2018 at 9:06 AM, sixgill pete said:

 

The teeth pictured from Elasmo, in my opinion are not C. limbatus. First, Purdy et al  (2001) does not include C. limbatus in their fauna list for Lee Creek. Second, at least in my opinion they are very poor matches when compared to an extant dentition. We all know how hard it is to assign most single teeth of Carcharhinus to a species accurately, yet we all try to do it; myself included.

 

 

Purdy 2001 is not a reliable guide.  Page 115 a "composite dentition" of Isurus oxyrinchus upper tooth 4 is hastalis, lower tooth 2 is completely out of place being a lower tooth 3 of the opposite side of the jaw.  Lower tooth 5 is another hastalis.  Lower tooth 6 is I. paucus (retroflexus).  This whole mess is inexcusable as modern jaws exist and tooth placement could have easily been compared with a modern jaw.  Page 116,  e and f are again I. paucus (retroflexus).   Page 117: upper tooth 4 and 7 is I. oxyrinchus.  Upper teeth 8-10 are too large for their position.  Lower tooth 3 is again I. oxyrinchus.  Lower tooth 6 is I. paucus (retroflexus).  Page 147 is not Galeocerdo instead is Physogaleus.  Page 153 many of the lower teeth are from C. obscurus.  Page 155 this species was identified to Purdy by me, it had not been originally included in the fauna as well.  I could go on but you get the idea.