In the heart of Shelterea's masssive desert, a strange creature makes it's home here. A fellow fish like the centaurs but the pegasi, but neuther closely related to it at all. Coming from an unlikely ancestor, The Reed Slitherer has adapted to the threat of invasion. Following it's plant comrades to the dusty warm desert.
The Quad-joints are the next terresital vertebrate clade derived from initial colonizers. More specifically the Three-spot Gourami. However it has gone through various noticeable changes, Their semi-prehensile feelers have strengthed and became muscular tentacles, their tail have became a strong arm. Infact this arm is how they get their name.
Their "arm" posseses at the base a "base joint". It's where the arm connects to the body with special "ball and socket: position, this allows it to move around 360 degress. The next joint is the elbow joint, though not as flexible as the base join still has it's strengths. Being able to flex and lock holding the animal in place, or storing energy up to sort of leap and propell. Next is the lower wrist joint, it's flexibility rivals that of the base joint. Completely allowing the quad join to look around and swing while the brachioradials us locked. Finally we have the up wrist joint, surprisingly stiff compared to the lower wrist. However it can turn thanks to said lower wrist. This complex arm structure will pave the way for various aboreal adaptations.
This particular species is an omnivore, feeding on the little interior shrub's fruits or on terrestial copepods. Spending their entire lives on one little bush except during mating season. During the purple nights they emerge in large numbers. Turning it into a furious orgy, males and females engaging in seuxal behavior with each other. Once dawn breaks, they all return to their own little shrub. Females wait til larger herbivores come, climbing onto their fur and laying 12-14 eggs. Though they won't stick on like parasites, instead they are supposed to be dropped along the way by unclaimed bushes. This usually doesn't happen and only 1-3 out of the clutch of 12-14 eggs survive.
Some populations though have been approaching out of the desert, along with their life-long partner shrub. Being found on the leeward slopes of Shelterea's mountains, a bright future awaits them far ahead.