A GIGANTIC EDIACARAN FOSSIL FROM SIBERIA

The Precambrian is sometimes known as the Cryptozoic eon, or “the age of invisible life”, because most Precambrian fossils are microscopic. However, macroscopic fossils do occur in the Precambrian, and they can be abundant and diverse in Ediacaran rocks, where macroscopic soft-bodied life forms are preserved as casts/molds and carbonaceous compressions. Macroscopic carbonaceous compressions have been found in Ediacaran successions in China, East European Platform, the Urals, Siberian Platform, Canada, Australia, Spain, and southern Africa. These fossils are typically millimeters to centimeters in size, but can be up to 15 cm in length. The late Ediacaran Khatyspyt Formation in northern Siberia hosts a diverse assemblage of macroscopic carbonaceous compression fossils. Although most Khatyspyt fossils are fragmented and millimeters–centimeters in size, one of them reaches 20 cm in length and 3 m in length. This gigantic ribbon-shaped fossil is morphologically similar to but much larger than the Ediacaran fossil Mezenia kossovoyi from the East European Platform, which is only 5–6 mm in width and 3–4 cm in length. Careful analysis shows that this fossil has been morphologically modified by taphonomic dehydration and deformation. We tentatively interpret this fossil as a benthic macroalga with indeterminstic growth potential.