UNITED STATES (OBSERVATORY NEWS) — An international team of researchers has discovered in northern China the world’s oldest green algae fossils. The age of the find is estimated at one billion years.
Let us explain that there are three groups of algae: brown, green and red. Each of them has thousands of species. It is known that red algae, the most common today, existed as early as 1.047 billion years ago.
As for green algae, in the fossil record there are still no exact data on exactly when they arose. It is believed that plants capable of photosynthesis (the corresponding chlorophyll pigment is responsible for the green color) appeared somewhere between the Paleoproterozoic era (2500-1600 million years ago) and the period known as cryogeny (720-635 million years ago).
Specialists have long sought to establish a more accurate date. After all, it is assumed that it was thanks to the evolution of green algae that the development of diverse ecosystems and complex life forms on Earth became possible.
Regarding the origin of this group there is also no consensus. Some biologists believe that green algae first appeared in freshwater lakes and rivers and rather late “colonized” the sea. Another hypothesis is that green algae appeared in the oceans a long time ago and eventually adapted to life on land, giving rise to terrestrial plants.
The new discovery sheds light on both of these issues.
The fossils discovered in China are the “remains” of the species Proterocladus antiquus , a representative of marine green algae. This species, according to scientists, may be associated with the ancestor of the earliest land plants, which 450 million years ago began to “migrate” to land.
The authors of the study believe that P. antiquus once lined the seabed. They also clarify that their prints in sedimentary rocks have a length of only two to three millimeters and are barely visible to the naked eye.
It is noteworthy that these algae differ from other species of the genus Proterocladus in some features. This, for example, is the presence of a root-like structure and side branches growing upward.
“They have many branches, vertical growths and specialized cells known as akinets . Taken together, these signs convincingly indicate that the [discovered] fossil is a green alga with a complex multicellular structure, which is about a billion years old.
Thus, the history the ubiquitous green plants that we see today can be traced to at least this mark, “says co-author Shuhai Xiao of the Polytechnic University of Virginia.
He also added that some modern green algae are very similar to the fossils found. The greatest similarity in shape and size is the group of seaweed, known as siphon storage, said Professor Shuhai.
In addition, experts note that the fossils of P. antiquus are 200 million years older than the previous record holder. And since this species possessed a number of advanced features, it can be assumed that the very first green algae, much more primitive, appeared much earlier.
An article with a detailed description of the new find is presented in the journal Nature Ecology & Evolution.
This article is written and prepared by our foreign editors writing for OBSERVATORY NEWS from different countries around the world – material edited and published by OBSERVATORY staff in our newsroom.
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