the process by which different kinds of living organisms are thought to have developed and diversified from earlier forms during the history of the earth.
the process whereby organisms better adapted to their environment tend to survive and produce more offspring. The theory of its action was first fully expounded by Charles Darwin and is now believed to be the main process that brings about evolution.
Hippos likely evolved from a group of anthracotheres about 15 million years ago, the first whales evolved over 50 million years ago, and the ancestor of both these groups was terrestrial. These first whales, such as Pakicetus, were typical land animals.
The evidence for photosynthesis in the rock record is varied, but primary evidence comes from around 3000 Ma, in rock records and fossil evidence of cyanobacteria, photosynthesizing prokaryotic organisms