The plains hunter split from the beach slider. Some beach slider groups migrated to the Ovi-Hydro Plains. They live in gangs now, like Earth's meerkats. The alpha hermaphrodite only allows a number of members. If the group gets too big, the alpha hermaphrodite might kill a few babies to control the gang population and evict anyone who reproduces a lot. The maximum gang number is 30. If a predator comes, the entire gang makes a lot of noise using the vocal sac on the forehead and rapidly changes colors (in case the predator is able to see) to scare the predator away. If that doesn't work, they all throw rocks at the attacker. Plains Hunters hunt in packs, their common prey being leatherback scuttlecrabs. They still use toxin to paralyze the prey. Otherwise they can forage for orbiflors.
The manipulative tentacles' sides became extra digits so the plains hunter can grab things like food without dropping them. The arms grew longer and attached to the beak-like mouth. All chemo-receptive nerves migrated to a lump. The scent lumps can smell very well. The feet became upright, and the air sacs in the legs became fluid-filled to serve as "bone". The lungs grew bigger to supply the body with the oxygen it needs. The skin became thicker to adapt to the new land environment.