Convergent evolution

From SporeWiki, the knowledge base dedicated to Spore

The process by which creatures from varying evolutionary paths tend to take on the most efficient shape for their niche. For example, the dolphin (mammal), the extinct ichthyosaur (reptile), and the shark (cartilaginous fish) all share a similar shape in their body plans, implying that most large and fast water-dwelling animals (regardless of their heritage) will find this shape to be the most efficient simply through physics and natural selection.

In Spore, it may come to show that, despite a wide variety of imaginations amongst content creators using the creature editor, and at the top of the most succesful creatures, convergent shapes may still arise (bipedal sentients, lean quadruped predators, aerodynamic flyers).