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Description
here I tried to resolve some of the few remaining issues there were with ichthyids, I have finally figured out their propulsion system and skeletal system, as well as variability of their external anatomy. shame to say, the strut runnung the length of the body is a backbone with nerve chord inside. I am still a bit pissed because of that, but that's the most sensible solution of all which I have considered. the 'rib rings' are composed of four segments and they only support the gill chamber from collapsing onto itself. Only the first and last ring are attached to the vertebral column, with four struts each. the other rib rings are only supported by the musculature on the outside. before becoming terrestrial, the rib rings disconnected on the bottom, sunk in the body, gradually encompassing the internal organs, leaving only the lower two membranes in the propulsion chamber functional. most likely, the lower right ichthyid is something like earth's coelacanth. most ichthyids can forcibly expell water out of this chamber by flattenning it from the sides, which allows them to quickly zip away from predators (including larer ichthyids who rely more on fin strength than jet propulsion) sometimes even followed with a spray of excrement to deter them. the difference between the two major extant ichthyid clades does not only lie in the shape of fins and presence of protective plates, in the lineage more closely related to amphibious and subsequently terrestrial vertebrates, the lower exognath is jointed underneath the orbit and the upper exognath is jointed above the orbit, which is the basic jaw arrangement of the most primitive terrerstrial clades, while the "smooth ichthyids" have the lower exognath attached below and above the orbit, and the upper exognath forms a pincer-like structure with the lower exognath, being almost completely independent of the skull.

The topmost critter is just an experiment, the worm-like thing on the upper right still needs more work, but i plan it to be a descendant of the last common ancestor of these guys: [link] and the idhthyids.
The first striking difference is in their symetry, the "bony squids" remaining tetraradial like their ancestors, the originally tetraradial ichthyids gradually became biradial (both of these ancestral ichthyid groups are now extinct, but I still might draw them some time...) and then bilateral. the number and position of the jaws, number of eyes and general layout of fins still give away their tetraradial origins, as well as their (in most cases) four-membraned gill chamber, but their remaining organ systems are present only once, in contrast with the worm-like creature in the picture which follows tetraradial symetry even on the inside, as well as the "bony squids".

the remaining sketches are dealing with avicephalians again, but I am not sure whether I'll even use the concepts or not. the hummingbird-like one has almost lost its lower exognaths, only retaining long and slender upper exognaths and endognaths. The other sketch just shows a penguin-like avicephalid with its canards turned into dorsal fins.

Description
here I tried to resolve some of the few remaining issues there were with ichthyids, I have finally figured out their propulsion system and skeletal system, as well as variability of their external anatomy. shame to say, the strut runnung the length of the body is a backbone with nerve chord inside. I am still a bit pissed because of that, but that's the most sensible solution of all which I have considered. the 'rib rings' are composed of four segments and they only support the gill chamber from collapsing onto itself. Only the first and last ring are attached to the vertebral column, with four struts each. the other rib rings are only supported by the musculature on the outside. before becoming terrestrial, the rib rings disconnected on the bottom, sunk in the body, gradually encompassing the internal organs, leaving only the lower two membranes in the propulsion chamber functional. most likely, the lower right ichthyid is something like earth's coelacanth. most ichthyids can forcibly expell water out of this chamber by flattenning it from the sides, which allows them to quickly zip away from predators (including larer ichthyids who rely more on fin strength than jet propulsion) sometimes even followed with a spray of excrement to deter them. the difference between the two major extant ichthyid clades does not only lie in the shape of fins and presence of protective plates, in the lineage more closely related to amphibious and subsequently terrestrial vertebrates, the lower exognath is jointed underneath the orbit and the upper exognath is jointed above the orbit, which is the basic jaw arrangement of the most primitive terrerstrial clades, while the "smooth ichthyids" have the lower exognath attached below and above the orbit, and the upper exognath forms a pincer-like structure with the lower exognath, being almost completely independent of the skull.

The topmost critter is just an experiment, the worm-like thing on the upper right still needs more work, but i plan it to be a descendant of the last common ancestor of these guys: [link] and the idhthyids.
The first striking difference is in their symetry, the "bony squids" remaining tetraradial like their ancestors, the originally tetraradial ichthyids gradually became biradial (both of these ancestral ichthyid groups are now extinct, but I still might draw them some time...) and then bilateral. the number and position of the jaws, number of eyes and general layout of fins still give away their tetraradial origins, as well as their (in most cases) four-membraned gill chamber, but their remaining organ systems are present only once, in contrast with the worm-like creature in the picture which follows tetraradial symetry even on the inside, as well as the "bony squids".

the remaining sketches are dealing with avicephalians again, but I am not sure whether I'll even use the concepts or not. the hummingbird-like one has almost lost its lower exognaths, only retaining long and slender upper exognaths and endognaths. The other sketch just shows a penguin-like avicephalid with its canards turned into dorsal fins.