A fossil believed to be the oldest of its kind has been discovered by a Yorkshire-led team of scientists.
The fossil was found at Loch Torridon in the Northwest Scottish Highlands and has two distinct cell types which scientists say could be the earliest multicellular animal ever recorded.
The discovery was made by a team of scientists from the University of Sheffield and Boston college from the USA. The fossil shows an organism which lies somewhere between single cell and multicellular organisms.
Scientists say the fossil, now formally named Bicellum Brasieri in a new research paper, shows that the evolution of animals happened at least one billion years ago and might have occurred in freshwater lakes instead of the ocean.
The fossil also shows new insight into how single celled organisms eventually became multicellular animals as it shows an organism which lies somewhere between single cell and multicellular animals.
Professor Charles Wellman, one of the lead investigators of the research, from the University of Sheffield, said: “The origins 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.”
Scientists could study the fossil because of its “exceptional” preservation, allowing them to analyse it at a subcellular level.
Professor Paul Strother, lead investigator of the research from Boston College, said:
“Biologists have speculated that 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-to-cell adhesion and cell differentiation that may have been incorporated into the animal genome half a billion years later.”
The team hopes to examine Loch Torridon for more fossils in the future.