Earth’s oldest evidence of life is written in stone – but it’s at risk of disappearing
Despite a fossil record that spans billions of years, microbialites are surprisingly fragile.
Long before plants and animals dominated the Earth, a simpler form of life thrived in microbialites. These ancient structures, found in rocks dating back nearly 3.5 billion years in Western Australia's Pilbara region, represent the earliest visible evidence of life on our planet. Microbialites, mounded formations created by communities of microbes, have since evolved and persist today, albeit in a more delicate form.
Recent research published in the journal Alcheringa reviews 50 years of microbialite studies in Western Australia, shedding light on their role in Earth's evolution and current threats to these fragile structures.
Despite their long history, microbialites face significant challenges. Fossilized sites are vulnerable to over-collection and environmental degradation, while living microbialites are increasingly under pressure. In May 2024, for instance, a group of aurora chasers inadvertently damaged 2,000-year-old thrombolites at Lake Clifton by trampling over 2,000 years' worth of geological history.
The review highlights that microbialites not only provide insights into life's origins and the development of Earth's atmosphere but also serve as indicators of past ecological stress. Their presence in rocks spanning major mass extinctions suggests that microbialites may have served as early warning systems for environmental upheaval.
However, the review also points out critical knowledge gaps. Scientists are still uncertain about the exact environments in which ancient microbialites formed, whether modern examples accurately reflect their fossil counterparts, and the precise mechanisms behind their distinct shapes and structures. For instance, the clotted textures of thrombolites, as opposed to the layered stromatolites, remain a mystery.
Western Australia may hold some of the oldest thrombolites, but detailed studies are yet to be conducted, leaving many questions unanswered about these ancient, yet fragile, witnesses to life's enduring journey on Earth.
Written by urgent.news from The Conversation AU's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
