A billion-year-old fossil isolated in Scotland

A billion-year-old fossil isolated in Scotland

A billion-year-old fossil found in the Highlands of Scotland may stand as a “bridge” between unicellular and multicellular organisms. This discovery also suggests that the first forms of terrestrial life evolved in fresh water.

This is a discovery that we do not do everyday. Sediments of the Torridonian sequence of the highlands of north-western Scotland harbor a wide range of microfossils, documenting life in a non-marine environment several hundred million years ago.

Recently, a team from the University of Sheffield (United Kingdom) and Boston College (United States) isolated a new fossil from an even older one. loch toridone. Scientists were able to study these remains because of their exceptional conservation, which allowed them to be analyzed at the cellular and subcellular level.

this body, made there about a billion years, has now been named Biselm brasserie. Details of the study have been published in the journal current biology.

A bridge in the evolution of living things

The mature form of this organism, called Bicellum brasserie, occurs as a spherical mass of mutually expressed cells surrounded by a peripheral layer of elongated sausage-shaped cells. The inner cell mass forms a stereoblast of roughly isodiametric cells with an average diameter of about 2.5 µm.

However, the two populations of naked blast cells appear to exhibit early elongation, suggesting that they may have migrated to the periphery of the cell mass. These simple morphogenetic movements can be explained by an inter cell–cell adhesion.

So in a more simple way this organism can be detected Somewhere between a unicellular life form and a multicellular life form. For researchers, it seems reasonable to assume that B. Brassiri is one of the lineages that today is one of six groups that developed complex multicellularity: animals, plants, floridophytic algae, brown algae, ascomycete fungi and basidiomycete fungi.

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“We found a primitive spherical organism composed of an arrangement of two different types of cells, the first step towards a complex multicellular structure. This is something that has never been described before in the fossil record”, underlines Charles Wellman, the main author of this work.

“The origin of complex multicellularity and the origin of animals are considered to be two of the most important events in the history of life on Earth”, she added. “Here, our discovery sheds new light on these two elements”.

Some elongated cells are visible at the periphery of the cell mass. However, a clearly distinct epidermal layer has not yet been established. Note that there is no clear distinction between the cell walls of either cell type. credit: Current Biology

This new discovery also suggests that this evolution occurred in freshwater rather than in the ocean. The team aims to continue research in these repositories. The discovery of new and more interesting fossils could provide more information about the evolution of multicellular organisms.

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