Gnathospsari

Gnatospsari means jawed fish, and it will be the ancestor of almost all fish like kinds

The upper dark bluish part is covered with shell, composed mostly of calcium carbonate. It contains chemical senser that acts as "nose" for smelling.

The Main body, is muscular in order to swim easily in the dense water. It doesn't have gills yet, so it will passively breathe as water goes inside its body and spit water back. It breathes and eat with the same mouth. Its digestive system is simple with only stomach and a tube towards the back of their body. The stomach digests the food and absorbs nutrient at the same time, and the waste will be excreted by the "tube" (somewhat intestines I guess)

The lower head, is the jaw. It was mainly used for storing marine snow, but as teeth evolved, it also became means of attacking and killing the prey. It can also detect some level of movement by vibration.

4500 million years after the planet was borne, the gnatospsari will have to diverge into different niches and species or face extinction.

Clade
Gigantospsari

Spiropsari