LIFE × EVOLUTION

The First Predators

~780 to 740 million years ago

Proterozoic · Neoproterozoic · Tonian

Some cells began eating other cells from the outside in. In shales laid down where the Grand Canyon now cuts, seven species of microfossil carry round holes bored clean through the wall, 0.1 to 3.4 microns across: the size and shape of the holes predatory protists drill today to reach the contents of their prey. At least some of the prey are unmistakably complex cells. Of the predators, nothing survives but the holes.

Why it matters

Being eaten is a new kind of pressure, and it makes defences worth their cost: a thicker wall, a bigger body, a spine. The ornamented cysts that fill the rocks of this age start to look less like decoration and more like armour.

Dating & uncertainty

Circular holes a few microns across, drilled through the walls of microfossils in the Grand Canyon, match the way modern predatory protists open their prey. Similar perforations, read as probable traces of the same kind of predation, have since been reported in Arctic Canada in rocks of about 1150 to 900 Ma, which would push the behaviour back by 150 to 400 million years.

Sources

1. Porter (2016), Proceedings of the Royal Society B · Tiny vampires in ancient seas: evidence for predation via perforation in fossils from the Chuar Group
2. Loron et al. (2018), Emerging Topics in Life Sciences · Implications of selective predation on the macroevolution of eukaryotes
3. Porter & Riedman (2016), Journal of Paleontology · Systematics of organic-walled microfossils from the Chuar Group, Grand Canyon

Earth history as one day

19:52:354 h 7 min before midnight

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