Charnia masoni - possibly the most iconic of all Precambrian lifeforms. Charnia was the first organism to be acknowledged as a Precambrian complex lifeform. Its discovery reinvigorated Precambrian research leading to the establishment of the Ediacaran Period within the geological timeline and the recognition of its unique biota.
Charnia is notable not only as the first recognized Ediacaran lifeform but also for its mysterious nature. A sessile organism that lived deep in the ocean, beyond sunlight’s reach - ruling out photosynthesis and suggesting it wasn't a plant or alga - Charnia also lacked animal traits like a gut or mouth, making its classification problematic. If not flora or fauna, then what?
Charnia is currently thought to be a member of the enigmatic rangeomorphs - frond-like organisms that flourished during the Ediacaran period (635 - 538 Mya). It was discovered in 1957 by schoolboy Roger Mason (Ford, 1958), in the English Charnwood Forest - within sedimentary rocks that predated the Cambrian period. As such it is recognised as one of the first multi-cellular, complex lifeforms to appear on Earth (Narbonne, Gehling, 2003)
Charnia has a fractal-like anatomy - built up of simple reoccurring patterns of hydrostatic cellular units - offset along the bilateral line. This offset is known as glide reflection and predates the bilateral symmetry that is common to most modern animals. More recent examinations indicate that by the fourth and possibly even third order of branching, variation in branch units starts to occur - placing a question mark over its fractal classification as a Rangeomorph (Dunn, et al. 2018).
Along with many other Ediacaran organisms it is not known how Charnia acquired food from the environment. As most Ediacaran creatures show no sign of a gut it is thought they probably absorbed nutrients by osmosis- directly through the cell wall.
The discovery of Charnia was an important step towards the resolution of "Darwin's Dilemma".
"Darwin's Dilemma" refers to the apparent absence - during Darwin's lifetime and beyond - of any evidence of complex life prior to the "Cambrian Explosion". How could complex life so suddenly appear in the fossil record without any apparent ancestry?
Since the discovery of Charnia many more Precambrian fossils have been found around the world and although affinities are yet to be agreed upon the Ediacaran biota is unambiguously an earlier more primitive form of life - indicating that the Cambrian Explosion was not an event in isolation.
With thanks to Dr Jean-Bernard Caron and Dr Emily MItchell for feedback on anatomical detail.
