The Strange Fauna of 18Scorpii-4

On 18Scorpii-4, the animals that make up the majority of the megafauna are vertebrates with physical characteristics associated with arthropods: chitinous external carapaces, articulated antennae used for smelling, bodies segmented by their carapaces, etc.
In reality, their internal anatomy demonstrates their similarity to Earth's vertebrates. The key difference is that some bones are structured differently, such as the absence of ribs, but rather comb-like bones, fewer vertebrae, etc. Therefore, it was decided to name these « new type of bones » with new terms and combine certain anatomical terms from vertebrates and arthropods to create a new nomenclature specific to this planet.

Their classification is further complicated by this anatomy, which is unusual for Earthlings. Due to a lack of time, originality, and creativity on the part of the expedition's naturalists, it was decided that, pending proper taxonomic names, the main groups of these animals would be temporarily designated by codes.
These vertebrates (basically nicknamed Sherudobutsians) are grouped into three non taxonomic categories that identify them according to their number of members in their adult stage.
The Decapods, which appear to consist of only one group; the Octopods, composed of four groups with highly varied morphologies; and the Hexapods, which have diversified the most with seven different groups.