Nannotax Enabling nannofossil research

The extinction of this species can be a good Miocene marker, but lower range of this species is problematic. Most of the other Neogene workers I've spoken with agree. Below NN4 you continue to periodically see pulses of very large C. pelagicus in this size range (> 13or 14 μm) all the way down into the Oligocene. Eventually, working down section, you start seeing specimens on the order of 20 μm and if you are paying attention, they can be called C. eopelagicus. This isn't very scientific, but it is what happens. There are some workers who distinguish this species on something other than size. They tend not to measure, or sometimes call smaller specimens something like “C. miopelagicus small” At that point the upper range also becomes a problem.

My split on the Pelagicus group works like this:
< 10μm = C. Pelagicus
10 μm - 13 μm = C. cf. miopelagicus
13 μm - ~20 μm = C. miopelagicus
~20+ μm and Oligocene or older = C. eopelagicus

Notice that the only real age caveat is for C. eopelagicus. For the rest I call them whatever age they are. I encourage contractors who do work for me to use this system as well (some just can’t bring themselves to do it). I understand that this is a very industrial approach, and that it is probably not strictly to code, but it avoids confusion. I know others I know others have had a pretty hard look at this group and I hope they see fit to comment here!