Polydactyls are a group of creatures native to planet Snaiad. Species in this group are united by the presence of multiple digits on their front and rear limbs.
These digits are thought to be derived from the multitudinous, centipede-like tube-limbs of even earlier “vertebrate” ancestors. As the tube-like feet merged and bundled over the course of Snaiadi “vertebrate” evolution, some took the role of fluid-filled hydraulic muscles, others became bone-like support structures or degraded into more conventional fibrous muscles, and yet others protruded from the tips of extremities like digits. As the majority of large Snaiadi land animals have two digits per limb, a trend towards reducing these digits and incorporating them inside the arms and legs must have taken place as more “advanced vertebrates” evolved from Polydactyls or Polydactyl-like ancestors.
Today, the different Polydactyl groups occupy a number of low-key niches all over the planet. Although most of these are fairly small and unremarkable animals, fossil evidence indicates that certain lineages, now extinct, grew to megafaunal sizes far earlier in the planet’s natural history. The unusual Turtiformes might also be Polydactyls.