This is the newest stage in the evolution of silvanian vertebrate live. Strange underwater fliers with simple jaws.
Rugognathus lengus is a inhabitant of the shallow waters, for the most tiem of their life these animals lay on the ground und pump plankon rich water through their guts. Thanks to the perfect camouflge of their skin they can do this nearly undisturbed.
Abelia is also a filter feeder but a very different. Some of you know this genera already from my "things which don't fit into the scanner" series. The hook/rake of species like Haminasus wegneri became more bigger and sits now on an elongated part of the spine, a "pseudo-neck". At this animal the rake is used to skratch organic material of all sorts out of cracks and holes. Some stationary organisms which are related to Utertitan use this creatures as for their spores, in a similar manner how flovers on earth it do.
The family of Dubiobrachius is even a bit more derived. The develope the rake into a jaw-like trap for everything which comes in it. There are many species of this fancinating predators and this is just a middle sized, "short necked" genera. Other dubiobrachids have much weirder propotions. After killing the pray the monster open it's real jaws and let it glide directly into its big stomach.