Dickinsonia

Dickinsonia is a genus of extinct, soft-bodied marine organisms from the late Ediacaran period, known from fossil impressions that date to roughly 550 million years ago. The genus includes several species, with Dickinsonia costata widely treated as the type species. Specimens are generally large and flattened, oval to elongated, and typically lie on or just above microbial mats on the seafloor. Individual forms range from a few centimeters to more than a meter in length. The exterior is smooth-edged, and many fossils show a pattern of transverse, rib-like segments along the length, giving a segmented appearance. The internal anatomy is poorly understood; no definitive mouth or gut has been identified in the fossils, and it remains uncertain whether Dickinsonia possessed true tissues.

Fossils have been found at several Ediacaran sites, most famously at the Ediacara Hills in South Australia and in the White Sea region of Russia, indicating a broad geographic distribution in late Precambrian seas.

Taxonomy and interpretation of Dickinsonia have long been debated. For decades it has been described by many researchers as a metazoan (early animal), but some scientists have proposed alternative affinities, such as giant protists. The lack of definitive anatomical features complicates precise placement, and Dickinsonia remains a prominent subject in discussions of early multicellular life and pre-Cambrian ecosystems.

As one of the best-known Ediacaran fossils, Dickinsonia provides important insight into the diversity and morphology of early complex life before the Cambrian explosion.