Researchers at the Australian National University have discovered traces of ancient biota that dominated life on Earth nearly a billion years ago. Biomarker signatures found in rocks 1.64 billion years old indicate that these organisms may have been the first predators on Earth, feeding on microbes in the world’s oceans before plants, animals and fungi emerged.
Researchers called these organisms protosterol biota. They were unlike anything alive today and appear to be the ancestors of all eukaryotic life on Earth, including us. They were large and complex organisms that thrived on the next food chain, hunting and devouring bacteria.
Since eukaryotic life dominates today, scientists believe it must have appeared more than a billion years ago. However, identifying ancient organisms is challenging at best, since any traces they may have left behind are probably extremely degraded.
The discovery was made while analyzing rocks from waterways around the world, the oldest of which were from the Barney Creek Formation in Australia, dating back 1.64 billion years. Researchers used a combination of methods to convert various modern steroids into their fossil equivalents to find steroids, a biomarker of early eukaryotes.
The discovery shows that these eukaryotic biomarkers have been hiding in plain sight all along, although what the creatures that produced them looked like remains unknown, since no fossils of the creatures themselves have been found.
“The molecular remains of protosterol biota found in rocks 1.6 billion years old appear to be the oldest remnants of our own lineage,” says Benjamin Nettersheim, one of the discoverers.
These ancient organisms were abundant in marine ecosystems around the world and probably shaped ecosystems for most of Earth’s history.
The study of ancient protosterol biota helps scientists better understand the early history of life on Earth and its evolution. However, because this is only the beginning of the study, scientists hope to discover more traces of these ancient organisms and uncover more of the mysteries of early life on Earth.