Alien Worlds creatures reimagined as earth animals
Skygrazers: a lineage of sauropterygians that developed lateral collagen fins, first to allow them to glide like flying fish but then having grown enough to provide lift for permanent flight, while the wings formed from the limbs provide thrust and steering. Spend their entire lives thermally soaring through the air, even giving birth on the wing. Some species feed on aerial plankton (seeds, insects, spiders et cetera) while others opt for more predatorial ecologies like those of frigatebirds.
Balloon Predators: a lineage of spiders that became more specialised to ballooning. In windless conditions they launch their webs, suspended on electricity high up in the air until they spot prey. Then they release their webs and spread their flattened, wing-like legs to glide down towards their prey — or, failing that, the ground.
Boneless Scavengers: a lineage of terrestrial echinoderms related to sea stars that developed an hydralic locomotion system to slither after their prey much as they did on the sea.
Pentapods: a lineage of terrestrial echinoderms related to crinoids that developed functional, arthropod-like legs from their stalks. Another set of stalks is still employed to pick up small animals and plants to eat, while yet another developed eyes on their ends. They are highly adaptable, occuring in nearly every terrestrial habitat and bearing developmental variations like stockier proportions and fur on colder climates or slender proportions and a reflective carapace on desert environments. Their larvae bear wings and are scattered by the wind much like winged seeds.
Grazers: a lineage of highly specialised endothermic slugs covered in air and that have seperated their eyes from their stalks: the former have become more complex and layered and the latter have become moth-like antennae. They reproduce by release their gonads which worm around until they find other gonads; then they fuse and form a cocoon that attaches to plant roots and absorbs their nutrients, gestating a young that will be born fully formed. Most are herbivores though some have specialised towards fungivory.
Predators: a lineage of arboreal eutriconodonts that superficially resembles tarsiers or aye-ayes. They are obligate carnivores that hop on their prey, using their thumbs to kill them. They bear complex social behaviours, often coordinating hunts.
Terrans: the next generation of melons.