Here we have convergent evolution (this is the independent evolution of similar features in species of different lineages), in this case evolution of alien life forms on Earth-like world. Alien trees with clusters of seedpods wait for unseen flying creatures to eat and disperse the seeds. Manta-like rays leap into the air, streamlined like fish on Earth, dark on top and lighter underneath just like other marine animals - puffins, penguins, dolphins, etc .