system
Given the following post, respond as if you're commenting on Reddit:
human
Between Eusthenopteron and Panderichthys what happened to the anal fin?

Looking at the charts of evolution of land animals the anal fin disappears between Eusthenopteron and Panderichthys. Do they become part of the pelvis? Do the bones of the anal fin simply stop being being created? Some combination or do they change in some other way all together?
gpt
The dorsal and anal fins are unpaired fins, and form separately from the pelvic girdle from which the paired pelvic fins are attached.  In the Elpistostegalia, the dorsal and anal fin are lost and don’t reappear in any later tetrapods.  The tail (caudal) fin is retained in some forms, and still observed in some larval amphibians. The loss of the unpaired fins was a developmental (genetic) event during the evolution of the lineage.