Transplutolithic Period

The Transplutolithic Period is the geologic period lasting from 3 to 3.5 billion years ago. Originally assigned to cover every rock and mineral beyond 3 Ga (giga-annum) in age, its name comes from its status as being "across" the Plutolithic Era. It is preceded by the Natalian period and followed by the Dorasterrolithic. The period itself was not defined by any specific rock deposits, but by age alone- hence its rather 'clean' boundaries setting it at exactly 500 million years in length.

Actual conditions during this period were mild, from what can be inferred from the geologic record. The climate remained mostly stable, and tectonic activity was minimal. Furthermore, there is no known indication of major asteroid impacts or other catastrophic events.

The first traces of photosynthetic organisms are known from fossilized stromatolites and algal mats similar to those found today. These ancient structures date to the later half of the period, roughly 3.3 to 3.1 Ga ago, and were likely made by cyanobacteria.

The implication that the first living organisms were not photosynthetic is a breakthrough in the understanding of the evolution of life; many paleontologists and geologists have hypothesized that a dilution of the "primordial soup", long depended on as an abiotic food source for the first organisms, forced the microbes of the time to evolve autotrophic methods of feeding themselves. From these early autotrophs, microbial ecosystems of producers and consumers likely began soon after.