ANATOMY

Detailed explanation-1: -The earliest life forms we know of were microscopic organisms (microbes) that left signals of their presence in rocks about 3.7 billion years old. The signals consisted of a type of carbon molecule that is produced by living things.

Detailed explanation-2: -Prokaryotes were the earliest life forms, simple creatures that fed on carbon compounds that were accumulating in Earth’s early oceans.

Detailed explanation-3: -The first bacteria evolved more than 3 billion years ago and dominated the biosphere continually thereafter, shaping the environment in which animals would eventually evolve more than 2 billion years later (Narbonne 2005; Knoll 2011).

Detailed explanation-4: -Bacteria have existed from very early in the history of life on Earth. Bacteria fossils discovered in rocks date from at least the Devonian Period (419.2 million to 358.9 million years ago), and there are convincing arguments that bacteria have been present since early Precambrian time, about 3.5 billion years ago.

Detailed explanation-5: -In the oceans of our young planet, bacteria were among the first forms of life to emerge. Long before plants or animals had evolved, bacterial colonies flourished and grew.