Dinosaurs dying off might not have be been the biggest mass extinction on Earth

• Clues found in Canadian rocks indicate that a mass extinction bigger than the dinosaurs dying 65 million years might have taken place on Earth.
• During that time, Earth lost nearly two-thirds of its plant and animal species.
• The extinction made way for larger animals to thrive as smaller microorganisms died off.

An asteroid striking Earth and spelling disaster for the dinosaurs is the largest mass extinction event known to man — but that might no longer be the case.

Rocks found in Canada indicate that there might have been an even larger mass extinction before the end of the dinosaurs. And, it eliminated two-thirds of plant and animal life on Earth 2 billion years ago.

Instead of a complex life, scientists believe that the mass extinction largely included microorganisms that built the Earth’s atmosphere. This had made way for larger animals to thrive.

“This shows that even when biology on Earth is comprised entirely of microbes, you can still have what could be considered an enormous die-off event that otherwise is not recorded in the fossil record,” said Malcolm Hodgskiss, co-lead author of a new study published in Proceedings of the National Academy of Sciences.

Looking beyond fossils

When looking for microorganisms that existed nearly 2 billion years ago, fossils can’t help. Instead, the scientists when looking for clues in mud and rocks.

They found barite crystals in the Belcher Islands of Canada’s Hudson Bay that showed a record of oxygen in the atmosphere. And, 2.05 billion years ago there were huge changes in the biosphere where the planet was filled with living organisms — and then it wasn’t.

Too little or too much oxygen

The phenomenon also supports the theory of ‘oxygen overshoot’. As per its stipulates, photosynthesis from ancient microorganisms and eroding rocks created a lot of oxygen that eventually ran out. The same oxygen omitting organisms exhausted their nutrient supply and died.

Today, the oxygen consumed and exhausted within the planet, more or less, balances out.

But knowing how an ‘oxygen overshoot’ plays out helps scientists determine what would happen if Earth were to have too much or too little oxygen within its atmosphere.

See also:
For an asteroid to wipe out humans, it has to be bigger than the one that killed the dinosaurs

Penguins as big as humans survived whatever killed the dinosaurs — as per fossils in New Zealand

How dinosaurs took over the world