Amphibia first appeared in which of the following periods?

Tailless amphibians are the members of the group

The limbless amphibian is

Give a scientific reason: Amphibia shows adaptation for terrestrial as well as aquatic life.

The main difference between Gymnophiona $(Apoda)$ and Urodela is that Urodela:

Which of the following is $NOT$ true for the $Axolotl$ larva?
$(I)$ It exhibits neoteny and paedogenesis.
$(II)$ The absence of thyroxine affects metamorphosis.
$(III)$ It is a hemichordate larva.