Retropodiadae is an order of Nrin vertebrate evolved in isolation of other dominant taxa. The order is a highly derived form of the ancestral land dwelling bipedal jawed vertebrate. It had occupied a niche of a small ambush predator in thickets and bushes.

The defining characteristic of the order is it's calcified head and laterally reversed hind leg arrangement. The head gained a hard shell, derived beak, as protection from higher tier predators. Because of reduced head mobility, these organisms lost their jaws and, instead evolved a muscular proboscis, which is a hollow structure constructed from two layers of muscle with a hydrostatic component between. The leg arrangement is a consequence of hanging from branches and swinging at it's prey in order to add extra kinetic energy to it's darting proboscis. The rectum and uterus are placed in a pouch like extension of the body. This structure is muscular and aids in mating, serving as a penis in males and as a uteral wall in females. It also acts as a buffer zone of the digestive system. The sensory organs on its beak are analogous to nostrils in other animals. It serves a function as a low energy light pit, a chemoreceptor, and a respiratory spiracle.

After being isolated from many of the more commonplace species, Retropodidae differentiated to fit their new ecology. Since the Nirn autotrophs had no natural enemies at that point, they prospered greatly, this incentivised some of the retropods to adapt to a primary consumer lifestyle. Yet others were fierce predators.

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