Is THIS the missing link in the evolution of animals? A BILLION-year-old fossil discovered in the Scottish Highlands reveals a new insight into the transition of single-celled organisms into multicellular creatures
- Earliest known organism with two cell types found in a fossil found in Scotland
- The fossil has been called Bicellum Brasieri and is around one billion years old
- It paints a picture as to how life proliferated from simplistic single-cell organisms into today’s myriad fauna
A billion-year-old fossil unearthed in the Scottish Highlands is being hailed as a crucial ‘missing link’ in the evolution of life, according to new research.
The fossil was found at Loch Torridon and reveals an organism which is more complex than a single-celled creature, but is not truly multicellular.
It occupies an archaeological niche and sheds light on how the most primitive lifeforms evolved into the myriad fauna we see today.
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The fossil has been called Bicellum Brasieri and fills a gap between the emergence of single-celled life and the ‘Cambrian Explosion’ 600 million years ago which saw a huge diversification
The fossil is thought to be the earliest known example of an organism which contains two distinct cell types.
Single-celled life, called prokaryotes, first appeared on Earth almost four billion years ago, when the planet and Solar System were in their infancy.
The fossil has been called Bicellum Brasieri and fills a gap between the emergence of single-celled life and the ‘Cambrian Explosion’ 600 million years ago which saw a huge diversification.
At this time oxygen levels in the atmosphere soared which led to a huge proliferation in the numbers of species alive.
The time between these events is known as the Proterozoic era – and little is known about it.
Lead author of the study Professor Charles Wellman, of the University of Sheffield, said: ‘The origins of complex multicellularity and the origin of animals are considered two of the most important events in the history of life on Earth.
‘Our discovery sheds new light on both of these.
‘We have found a primitive spherical organism made up of an arrangement of two distinct cell types, the first step towards a complex multicellular structure, something which has never been described before in the fossil record.
‘The discovery of this new fossil suggests to us that the evolution of multicellular animals had occurred at least one billion years ago and that early events prior to the evolution of animals may have occurred in freshwater like lakes rather than the ocean.’
The fossil was found at Loch Torridon (pictured) and reveals an organism which is more complex than a single-celled creature, but is not truly multicellular
It marks a key moment when bacteria became capable of photosynthesis and sexual reproduction which laid the foundations for much of life today.
Bicellum was found in rocks around Loch Torridon, a hotspot for finding the preserved remains of a plethora of animals.
It’s believed the extinct organisms that once lived at the bottom of lakes gave rise to green algae and land plants.
Co-lead author Professor Paul Strother, of Boston College in Massachusetts, said: ‘Biologists have speculated the origin of animals included the incorporation and repurposing of prior genes that had evolved earlier in unicellular organisms.
‘What we see in Bicellum is an example of such a genetic system, involving cell-cell adhesion and cell differentiation that may have been incorporated into the animal genome half a billion years later.’
The fossil is described in full in Current Biology.