Every time a cell divides, half of its chromosomes go to one daughter cell and another half of the chromosomes go to the other daughter cell. although the chromosomes split, each daughter cell ends up having the same number of chromosomes as the original cell. why is this?

this is a good question! i'll do some research and come back when i have the answer!

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.