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From the Calvert formation. Ruler in metrics

I am fairly comfortable with the STH micros as far as identification goes but I found a few things that I need some help with. First up is one that I am 90% sure on the ID but I want to be sure. I believe I found a couple of Raja teeth. The first one I found looks to be complete and tiny, a little over 1mm. I know skate teeth are somewhat uncommon in this fauna and this would be my first one.

Hello, I am currently re-sorting my collection and this brings up some questions about some modern shark teeth. For example, I found two teeth of this appearance. At first glance, I would suspect a Carcharhinus species (like C. falcifromis, but the teeth look different) , but I don't know which. Unfortunately, I don't find any comparable teeth in the Internet. Even if this isn't a fossil this time, I hope that you can help me again. The tooth is 1,3cm (0,51") in size and from the philippines. Best regards from Germany!

So I was recently going thru some Florida tooth material (Mio/Plio-Pleistocene) from years ago and realized I had lumped a bunch of this stuff in a packet without investigating them too thoroughly. I started to bug Jeff about several and thought I'd see what you all thought as well so I could learn something more from you all. So just 4 teeth for this thread. I was noticing #1's serrations were pretty coarse and well developed and unusual and I was asking about its possibilities and the meg possibility came up. I then found #2 tonight in another bag and it has some similarities to #1. Neither seem very thick/robust or show a bourlette but their serrations are definitely different than most I have seen. #3 has those finer serrations and shape I usually have put into the Carcharhinus ID bucket. Could they all be Carcharhinus? And lastly #4 may be pathological? What say you all? I know messing with single teeth ID's is pushing the envelope but appreciate any thoughts... Here's another view of just # 1 and #2. And lastly #4: Thanks for the help. Regards, Chris

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!