how do frogs evole

How did frogs evolve?
Frogs evolved from ancestors that looked like living salamanders which themselves look like lizards with smooth moist skins instead of dry scaly skins. Frogs probably evolved in the Triassic, more than 200 million years ago.

The first fossil that everyone agrees is almost certainly a frog is Triadobatrachus from the Lower Triassic in Madagascar. The Lower Triassic was approximately 240 to 245 million years ago.

But imagine how difficult it is to identify the "first" of any kind of plant or animal. You need a fossil that shows the critical feature of that group of animals. What part of a frog do you think you would need to tell that it was a frog. One tooth? One toe bone? A leg bone?

thanks this means so much to me