The migration of the preoperculum, quadrate and jugal from placoderms > catfish

Quick one today
as the title and graphic animation tell the story here (Fig 1). Three cheek elements, the preoperculum, quadrate and jugal rotate during evolution in this phylogenetic series of placoderms to catfish.

In this clade the jugal forms the operculum,
distinct from the genesis of the operculum in the Birkenia clade that gave rise to tetrapods and both are distinct from the genesis of the operculum in sturgeons.

All three ended up with convergent opercula generated from different facial bones.

Figure 1. Entelognathus, Holonema and Clarias demonstrate how the light yellow preoperculum originated anterior to the red quadrate, then rotated along with the cyan jugal homolog to the rear of the red quadrate. Note the splitting of the preoperculum in two.

This is not what they teach in university fish classes.
This is what the LRT is recovering presently. Still a work in progress.