Which is the best explanation for why you may not always be able to observe rocks transforming from one type to another? a most all rock is transformed beneath the surface of the earth. b the transformation of rock happens slowly over a very long time period in the geologic time scale. c most all rock is transformed by molten magma inside a volcano. d the transformation of rock happens faster than we can observe.

the oldest known insects are believed to live around 400 millions ago as suggested by the fossil records.   some plants having woody stems also evolved during this time.

after the evolution of insects the first four legged species or the tetrapods evolved in shallow freshwater habitats from the intermediate species approximately 397 million years ago. the tetrapods went on conquering the land giving rise to amphibians, reptiles, mammals and birds.

the major split in tetrapods first occurred 340 million years ago branching off from amphibians.

363 million years ago when the carboniferous period began the insects started roaming on land and taking flights, following which the four limbed tetrapods adapted in the terrestrial habitat.