Scientists examining a collection of old and new fossils recently discovered that an ancient species of bacteria, called Langiella scourfieldiiwas among the first to colonize the earth, more than 407 million years ago.
L. scourfieldii are a type of cyanobacteria that is part of Hapalosiphonaceae family. These microorganisms grew among early land plants during the Early Devonian.
Although cyanobacteria have long been documented by scientists, less is known about how these tiny photosynthesizing organisms managed to leave the water and live on land. New research conducted by Dr. However, Christine Strullu-Derrien, a paleobiologist at the National History Museum in the United Kingdom, and her team found that L. scourfieldii are the oldest species of cyanobacteria known to have lived on land—a discovery that helped fill in the gaps.
“Thanks to the 3D reconstructions, we were able to see evidence of branching, which is characteristic of Hapalosiphonacean cyanobacteria,” Strullu-Derrien explained in the paper. declaration.
“This is exciting because it means that these are the oldest cyanobacteria of this type found on land.”
Fossil cyanobacteria are among the oldest ever discovered, with the oldest estimated to be around 2 billion years old.
Otherwise known today as blue-green algae (a real case of a misnomer because they’re not algae), these bacteria live in and around aquatic environments all over the world, including oceans and rivers, but also on wet rocks (even in Antarctica). and in wet sand.
Cyanobacteria have played a vital role in shaping the history of our planet, helping to make it hospitable for complex life and influencing evolution more generally. Through their photosynthesis, they helped create the oxygen we need to live. They probably started with that A big action of oxygenationsometime between 2.4 and 2.1 billion years ago.
At this time, methane, which was the planet’s predominant gas, was replaced by oxygen and became the main component of the atmosphere. This event led to what is believed to be the first mass extinction, as anaerobic organisms failed to adapt to the conditions.
“Cyanobacteria played the same role in the Early Devonian as they do today,” added Dr Strullu-Derrien. “Some organisms use them for food, but they are also important for photosynthesis. We found that they were already present when plants began to colonize the earth, and perhaps even competed with them for space.”
What a difference to make Langiella scourfieldii make?
L. scourfieldii they were first discovered in 1959 in rock fragments found at the Rhynie Chert fossil site in Aberdeenshire, Scotland. However, these samples have been difficult to examine properly, but more recent samples have been obtained in the same area and are more amenable to analysis.
A key feature that Dr. What Strullu-Derrien and her colleagues were looking for were signs of “true branching”. This occurs when bacteria grow side by side in a row, with some breaking off in a different direction to form branches – but not all cyanobacteria show this true branching.
As such, a find L. scourfieldii in the Rhynia Chert samples is a big deal because it allows scientists to confirm that they were present in the moist terrestrial ecosystems in the area. Basically, they were able to make the leap from water to land and were able to thrive.
During the Early Devonian the landscape of this part of Scotland would have looked very different today. Earth would actually be closer to the equator and experience a much warmer tropical climate. This would make the Rhynia Chert an area covered in wet sand flats with pools of brackish water.
However, this was a time before trees and other complex life forms existed, so it would have been a much less lush environment. In such a sparse kingdom, fungi, bacteria and algae reigned supreme, competing for life on the rocks near the water’s edge.
As plants had not yet developed complex deep roots, they would have grown on the microbial mats formed by these microorganisms and formed an important interaction at this early stage of life on Earth.
“The Rhynie Chert is an iconic site because it is 400 million years old and much of the environment from that time has been preserved,” explained Dr Strullu-Derrien.
“It’s the only place where you find traces of all organisms together: plants, animals, fungi, bacteria and algae. You can see the interactions between species that would have occurred.”
The study is published in iScience.
