Ever wanted to see a living transitional? There are many creatures today that give insights into possible evolutionary pathways of the past. There are creatures today evolving in the same way that many of their relatives did so long ago. For example, the snake evolved from lizards (by losing its legs) and today we have lizards who found it advantageous to shed the legs. There are mammals like the duck-billed platypus and echidna, who have held on to reptilian traits such as laying eggs. The walking catfish's habitats are "Warm, stagnant, often hypoxic waters such as muddy ponds, canals, ditches, swamps and flooded prairies." This is exactly the sort of environment created by droughts during the Devonian, leading to amphibians and later to reptiles. Watch it walk here.
There's the flying squirrel, who illustrates a path for the evolution of flight. Who knows? In a million years it could be like a mammalian bird.