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I just made new ID posters for Hamilton Group Cephaloods - one for Nautiloids and Bactritoids, and one for ammonoids. The reconstructions are either new or updated for accuracy. Color patterns on the first picture are based on close relatives. If anyone has any suggestions, please let me know - I want these to be as useful as possible.

Hi everyone! I just got back from a trip to Penn Dixie Fossil Park near Buffalo, New York, and found some pyritized cephalopod fossils. Penn Dixie has rocks form the Givetian of the Devonian from the Hamilton Group. A young ammonoid is easily identified as Tornoceras uniangulare, but the other orthoconic fossils are harder to ID. I am pretty sure the small but more complete one is a Bactrites, because the siphuncle appears to be almost ventral, the distance between the septa, and the slightly slanted suture (after looking at Ludwigia's). The preserved shell is very smooth and couldn't be from a Spyroceras that are also found at Penn Dixie. Similar fossils to mine are pictured on their website, unidentified. If any more pictures are needed, I will try to take them. I wanted some expert advice before concluding it is a Bactrites. Can anyone help?

After a lot of research, I made this family tree for all of Cephalopoda. I have posted major resources below. Dates and lots of other stuff: https://paleobiodb.org/#/ Mass Extinction events https://samnoblemuseum.ou.edu/understanding-extinction/mass-extinctions/end-ordovician-extinction/ https://samnoblemuseum.ou.edu/understanding-extinction/mass-extinctions/late-devonian-extinctions/ Ammonoid classification: https://www.researchgate.net/publication/292489944_Fossil_Focus_Ammonoids Extinction of the Goniatites: https://www.nationalgeographic.com/history/article/121018-triassic-extinctions-hot-global-warming-science-environment Evolution of non-octobranchian coleoids: https://www.researchgate.net/publication/257132699_Longibelus_gen_nov_A_new_Cretaceous_coleoid_genus_linking_Belemnoidea_and_early_Decabrachia Evolution of octobranchians: https://static-content.springer.com/esm/art%3A10.1038%2Fs41467-022-28333-5/MediaObjects/41467_2022_28333_MOESM1_ESM.pdf https://www.nature.com/articles/s41467-022-28333-5 Extinction of the Ellesmocerids: https://onlinelibrary.wiley.com/doi/full/10.1111/j.1475-4983.2007.00644.x Early Spirulids; https://www.researchgate.net/publication/325588476_An_Early_Triassic_gladius_associated_with_soft_tissue_remains_from_Idaho_USA-a_squid-like_coleoid_cephalopod_at_the_onset_of_Mesozoic_Era And here is the family tree: