Study the table on the right.

The history of life on Earth can be divided into four geological eras. They are

• the Precambrian era,
• the Paleozoic era,
• the Mesozoic era,
• and the Cenozoic era.

The first cells and multicellular organisms developed during the Precambrian era. The first vertebrates, fish, began to develop in the water only about 600 million years ago. Dinosaurs ruled the Earth during the mighty Mesozoic era. Birds and mammals became the dominant life forms during the Cenozoic Era. The modern human species has developed only during the past million years.

Watch the video to find out more about the prehistoric timeline.

THE HISTORY OF LIFE

Era	Millions of years ago	Most important events	New organisms
The beginning of life	4 600	The first cells emerged.	Prokaryotes: archaea and bacteria
the Precambrian era	4 600 – 550	Photosynthesis provided energy for animals.	Eukaryotes, the first multicellular organisms
the Paleozoic era	550 – 250	In the beginning the life was only in the water, where fish evolved. Land-dwelling animals, such as amphibians and insects, developed towards the end of the era.	E.g. fish, amphibians, moss, ferns
the Mesozoic era	250 – 65	The era of reptiles.	Reptiles, birds, mammals, angiosperms (flowering plants)
the Cenozoic era	65 –	The diversification of birds and mammals.	Humans (5 million years ago)