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I am attaching images of Ordovician trilobites in my collection. I found the free, online Geological Survey Professional Paper 583-E to be very useful for identifying the Flexicalymene and Isotellus trilobites. Comments/suggestions/corrections are welcome. The 1st image is of Ordovician Flexicalymene meeki trilobites that I found in a creek bed in the Arnheim (sunset?) formation in Mt. Orab, Ohio. I identified these trilobites as F. meeki based on their relatively wide and sharp cephalons (heads). This is in contrast to the relatively narrow cephalons of F. retrorsa. The 2nd image is of a specimen collected on the same trip in the same same creek bed. The large fossil I have identified as the pygidium (tail) of the Isotellus maximus trilobite because it is not nearly as narrow and triangular as the pygidium of a I. gigantas trilobite. In the upper left is a prone flexicalymene trilobite that I have identified as an F. retrorsa due to the relatively narrow cephalon (compared to the body). If these identifications are correct then it is clear that all three species were contemporaneous. The third image is of a prone Flexicalymene retrorsa (my identification) trilobite from the Arnheim formation in Mt. Orab, Ohio. Note the relatively narrow cephalon (head). Image 4 is of a Isotellus maximus trilobite from the Ordovician Arnheim formation in Mt. Orab, Ohio. I identified this specimen based on the presence of genal spines on the cephalon as well as the relatively broad pygidium. Image 5 is of a larger, beat up Isotellus maximus trilobite from the Ordovician Arnheim formation in Mt. Orab, Ohio. I identified this specimen based on the presence of stubs of genal spines. Image 6 is of an Ordovician Cryptolithus instabilis trilobite from Buith Wells, Wales. I had previously found a small arc like fossil with perforations in Cincinnati and I had no idea about the source. I only recognized it after I saw the cephalon of the cryptolithus trilobite. This particular specimen has very little contrast with the bedrock so I altered the exposure and contrast in an effort to improve clarity. Image 7 is of a small, Ordovcian Amypxina bellatula trilobite from the Bellatula formation in Edgewood, MO. Image 8 is of a 505-438 MYA Diacalymene trilobite from the Ktaoua formation in Morocco.

During a trip today with a friend I found a large flexicalymene meeki. As well as some parts and partials of others. I also found some good gastropods and miscellaneous interesting fossils. The large flexi would be around 2 inches long if stretched out and it is just over an inch wide.

I found this mortality plate along AA Highway in Kentucky. Area is ordovician. I've been cleaning on this plate all night, when found this little guy under some dirt and brachiopod fragments. Did I just find a flexicalymene trilobite head? I know it's just a fragment and not the full thing. But I'd be pretty stoked if I'm correct on this. Thanks in advance. (I traced it out just in case my picture is too poor to see it. I can't find my macro lens)