Brachiognathiformes
Brachiognathiformes (meaning "arm-jaw form") is the clade which contains all descendants of the Eriken. They are named and distinguished from other stinzers by their distinctive, arm-like lateral mandibles. Some species also possess separate "hip" and "shoulder" girdles, making them significantly more flexible than their relatives.
Anatomy
Similar to most stinzers, Brachiognathiformes are typically tripods with have a hand at the end of a long tail-like limb. They have one pair of tympanic ears located on the head. Descendants of Pinsyk have highly flexible spines, while other species have far less flexible triangular bodies only capable of slight arching of the back. Ancestrally, they possess hollow quills formed from a ring of elongated scales which grow together. Their cloaca is located at the base of the tail rather than at the end like in many other stinzers.
The namesake of Brachiognathiformes is their flexible arm-like lateral mandibles. As they have a limit to their bite strength as a result of muscles attaching on the inside of the skull rather than the outside and putting pressure on the eyes when biting down hard, their ancestors adapted their lateral mandibles to do most of the work of grabbing or cutting food, eventually resulting in them being modified into the distinctive arm-like appendages this clade is known for. These mandibles are attached to the face by a ball socket joint. By default, the arm-mandibles can only be raised 90 degrees, meaning that Brachiognathiformes usually cannot raise them over their heads. They can be extended forwards, such as to grab food, and bent nearly all the way back to pull the food into the mouth.
The lower jaw (sometimes called "normal jaw" due to its resemblance to a Terran gnathostome's jaw) of Brachiognathiformes is often fairly deep, as their food-processing method is almost entirely tongue-based and therefore even carnivorous species require a strong tongue. They have many teeth lining the tongue and the roof of the mouth. Outside descendants of Pinsyk, the teeth are osteoderm-like and have a thick keratinous covering; in Pinsyk, the keratinous covering is thinner and designed to slough off to expose bony teeth which have a composition comparable to antlers.
Locomotion
Brachiognathiformes, be default, have semi-erect limbs. Like many other stinzers, they are typically facultative bipeds. They run by bounding, but they will usually walk on only two legs with an alternating gait, using their tail for balance. The hand at the end of the tail is not used in locomotion, instead mainly serving as a grasping appendage.