''Bicellum'' is a genus of fossil

holozoa Holozoa () is a clade of organisms that includes animals and their closest single-celled relatives, but excludes fungi and all other organisms. Together they amount to more than 1.5 million species of purely heterotrophic organisms, including a ...

ns containing the single species ''Bicellum brasieri''. It is one billion years old and could be the oldest example of complex multicellularity in the evolutionary lineage leading to the animals, and has been described as bridging "the gap between the very first living creatures — single-celled organisms — and more complex multicellular life." It was discovered in 2021, and is posthumously named after the late Martin Brasier, a paleontologist who was a co-author of the paper that first described it.

Fossil site

''Bicellum'' was found in sediments from the Diabaig Formation in

Loch Torridon Loch Torridon () is a sea loch on the west coast of Scotland in the Northwest Highlands. The loch was created by glacial processes and is in total around 15 miles (25 km) long. It has two sections: Upper Loch Torridon to landward, east of Ru ...

, Scotland. The Diabaig Formation, considered to represent an ancient lake deposit, was already known to preserve the first non-marine

eukaryote The eukaryotes ( ) constitute the Domain (biology), domain of Eukaryota or Eukarya, organisms whose Cell (biology), cells have a membrane-bound cell nucleus, nucleus. All animals, plants, Fungus, fungi, seaweeds, and many unicellular organisms ...

References

{{Taxonbar, from=Q106730787 Holozoa Fossils of Scotland Opisthokont genera Fossil protist genera Fossil taxa described in 2021