Syndactyly is the medical term for webbed or conjoined fingers or toes. In most cases the fingers are connected only by skin. It is rare that the bones are also fused together.
Dodo birds became extinct because of the combination of overhunting by humans and non-native predators that were introduced by humans to their native island. Dodo birds only inhabited the island of Mauritius, where they had no natural predators. Accordingly, the dodo bird had lost the power of flight and possessed few defensive behaviors by the time humans arrived on the island.
Raphus Replicare (more commonly known as the Dodo Bird) is quite possibly the dumbest creature I've ever seen in my life. It wanders around the beaches of the island, eating berries off bushes, and being eaten by all manner of carnivore. Without the Dodo, the entire island's food chain would disintegrate.