LIFE

The First Large Organisms, Perhaps

~2.1 billion years ago (biological origin disputed)

Proterozoic · Paleoproterozoic · Rhyacian

Flattened discs and lobed sheets up to twelve centimetres across lie preserved in fool's gold, in Gabonese rocks laid down just after the first oxygenation of the air. The rocks and their oxygen-rich setting are not in question; the shapes are. If they are organisms, they were coordinating their growth across many cells; if they are not, chemistry here learned to draw things that look uncannily like bodies.

Why it matters

It would place complex, cooperating life a billion and a half years before anything comparable in the record, which is exactly why it is contested.

Dating & uncertaintyDisputed

Centimetre-sized pyritised shapes in Gabonese black shales are read as colonies of organisms growing in a coordinated way, a billion and a half years before anything comparable. The rocks and their oxygenated setting are not in question; whether the shapes are bodies or mineral growths is still argued, and the surrounding microbial mats complicate the reading.

Sources

1. El Albani et al. (2010), Nature · Large colonial organisms with coordinated growth in oxygenated environments 2.1 Gyr ago
2. Aubineau et al. (2018), Geobiology · Unusual microbial mat-related structural diversity 2.1 billion years ago and implications for the Francevillian biota
3. Ikouanga et al. (2023), Precambrian Research · Taphonomy of early life (2.1 Ga) in the Francevillian basin, Gabon

Earth history as one day

12:53:5511 h 6 min before midnight

if Earth’s 4.54 billion years were compressed into a single day