Modern Carcharhinus dentitions

[verydeadthings 58]

Hi guys! I just uploaded a gallery of modern Carcharhinus upper dentitions:

. The images are from my master's thesis (Smith 2015), the full text is available at (https://www.researchgate.net/publication/316735477_Species_discrimination_in_Carcharhinus_shark_teeth_using_elliptic_Fourier_analysis). Unfortunately, due to file size limitations, the images in the paper are not really good enough for detailed analysis of the morphology. So I have uploaded them individually here. I personally extracted the teeth from almost all of these jaws...If I remember correctly, they were soaked in isopropyl alcohol for several days and then the teeth removed with toothpicks and/or just pulling them out with my fingers. I cut up my fingers too many times to count trying to get these suckers out! Only the upper dentition is included; the bottom teeth in Carcharhinus are very same-y so we just focused on the uppers. 

 

Keep in mind, these represent only twelve species out of over thirty described species. They are biased towards species today present in the Western Atlantic/Gulf of Mexico. Five species now present in the Western Atlantic/Gulf of Mexico were not included due to lack of specimens/time: C. altimus, C. galapagensis, C. perezi, C. porosus, and C. signatus.

 

Other Carcharhinus dentitions are available on the net. J-elasmo has some, I believe mostly collected from near Japan: http://naka.na.coocan.jp/JAWCarcharhinidae.html. They generally match well with my dentitions, although their Silky (C. falciformis) dentition is more coarsely serrated at the tips than mine, and the lateral notch, which is prominent in my specimens, is basically absent in the J-elasmo dentition. And of course there is Elasmo.com, a great resource for all sharks, not just Carcharhinus. Their C. falciformis dentition is similar to mine, so I don't know what's going on with J-elasmo's dentition, either it's mislabeled or Silky teeth look a lot different in the western Pacific. Or it's just an unusual specimen.

 

And of course there are a bunch of papers online with Carcharhinus teeth, although these are generally isolated fossil teeth. The single best resource I could find for Carcharhinus identication based on teeth is unfortunately difficult to obtain, and would probably require an interlibrary loan request: Garrick, J. A. F. (1982). Sharks of the genus Carcharhinus. US Dep. Commer. NOAA Tech. Rep. NMFS Circular, 445, 194. His shark teeth images are illustrations, but well done, and with a lot of descriptive information. Purdy et al. (2001) is also a good reference:(https://www.researchgate.net/publication/284595551_The_Neogene_sharks_rays_and_bony_fishes_from_Lee_Creek_Mine_Aurora_North_Carolina). You can find references to several papers related to fossil Carcharhinus, as well as a general overview of their fossil record, in my thesis.

 

Finally, I'm attaching a figure from my thesis, illustrating the morphological terminology used:

 

 

C. falciformis, upper right jaw, 5th position from symphysis.

 

Feel free to add additional references or information about the genus Carcharhinus. Or if anything is incorrect in this post. The subject of fossil Carcharhinus tooth identification comes up fairly regularly in the forums, so let's try and stick as much information in here as possible! 

 

 

[Al Dente 2,888]

Thanks for posting these. Are the darker, more detailed photos SEM? I’ve removed teeth from fresh jaws by simply simmering them in hot water for a few minutes and they drop out. I’ve had great difficulty removing teeth from dried jaws but I’ve never tried soaking them in alcohol.

[Brett Breakin' Rocks 615]

Wow, this is beautiful. Thank you for the post.  I have so much to catch up on.

 

Cheers,

B

[verydeadthings 58]

Yes, the darker photos are SEM

[MarcoSr 1,732]

On 11/18/2018 at 1:01 PM, verydeadthings said:

Other Carcharhinus dentitions are available on the net. J-elasmo has some, I believe mostly collected from near Japan: http://naka.na.coocan.jp/JAWCarcharhinidae.html. They generally match well with my dentitions, although their Silky (C. falciformis) dentition is more coarsely serrated at the tips than mine, and the lateral notch, which is prominent in my specimens, is basically absent in the J-elasmo dentition. And of course there is Elasmo.com, a great resource for all sharks, not just Carcharhinus. Their C. falciformis dentition is similar to mine, so I don't know what's going on with J-elasmo's dentition, either it's mislabeled or Silky teeth look a lot different in the western Pacific. Or it's just an unusual specimen.

 

 

 

 

Thank you for posting your dentitions.  I believe that J-elasmo has both the Carcharhinus albimarginatus: Tumajiro, Silvertip shark  and Carcharhinus falciformis: Kuro-togarizame, Silky shark dentitions mislabeled.  What J-elasmo has labeled as a silvertip shark dentition looks to me to be a silky shark dentition.  Plus the number of teeth in the J-elasmo silvertip dentition shown, 16/16, is outside of the range of  12 to 14/12 to 14 given by Compagno 1984 VOL. 4   SHARKS OF THE WORLD An Annotated and Illustrated Catalogue of Shark Species Known to Date Part 2 - Carcharhiniformes for a silvertip dentition.  Also all of my silky dentitions have upper teeth with prominent medial and lateral notches unlike the teeth in the J-elasmo silky dentition.  See the below pictures:

 

 

 

Marco Sr.

[MarcoSr 1,732]

On 11/18/2018 at 1:01 PM, verydeadthings said:

 

Only the upper dentition is included; the bottom teeth in Carcharhinus are very same-y so we just focused on the uppers. 

 

 

When I'm struggling with a Carcharhinus jaw id sometimes there is enough difference in the lower teeth to help confirm an id.  As an example, if one species has serrated lower teeth and another species doesn't have serrated lower teeth.  Also tooth counts help a lot with ids.  Although each Carcharhinus species has a range of tooth counts in both the upper and lower jaws, tooth counts outside a range helps eliminate species.

 

Marco Sr.

[verydeadthings 58]

Thanks for the info, Marco! Your interpretation of the J-elasmo dentitions makes sense to me. And Compagno (1984) is a great reference. Also Compagno's Sharks of the World Princeton Field Guide, which is quite affordable as a more general reference, and well illustrated.

 

Good point about the tooth counts for Carcharhinus sharks, very useful with modern jaws. Of course, not relevant with isolated fossil teeth. I considered including a morphometric analysis of the lower dentitions as well, but decided against it due to time constraints. I agree there are differences between species in the morphology of the lower dentitions, especially when combined with the upper dentitions. Ideally for modern specimens the identification is made based on dissection of the whole shark. 

[HoppeHunting 167]

Fascinating! Thank you for this. My AP Biology teacher has had a modern shark jaw with a complete dentition in her room for years without knowing what type of shark it belonged to. That is, until I was called upon to identify it for her! I was able to identify it as Carcharhinus sp. but didn't bother with an attempt at the species because the teeth of the dozens of sharks in the genus are often indistinguishable, as many of us know. But given your fantastic post, I may be able to narrow my identification and provide her with a few possible species! Thank you again for the interesting and informative post.