Meeting Abstract
The Ediacara Biota, Earth’s earliest communities of complex, macroscopic, multicellular organisms, appeared during the late Ediacaran Period, just prior to the Cambrian Explosion. Ediacara fossil assemblages consist of exceptionally preserved soft-bodied forms of enigmatic morphology and affinity which nonetheless represent a critical stepping-stone in the evolution of complex animal ecosystems. The Ediacara Biota has historically been divided into three successive Assemblages—the Avalon, the White Sea and the Nama. Although the oldest (Avalon) Assemblage documents the initial appearance of several groups of Ediacara taxa, the two younger (White Sea and Nama) Assemblages record a particularly striking ‘second wave’ of ecological innovations, including the rise of diverse Ediacara body plans—in tandem with the appearance of bilaterian animals—as well as the emergence of novel ecological strategies such as movement, sexual reproduction and biomineralization and the development of dense and heterogeneous benthic communities. Intriguingly, many of these ecological innovations appear to be linked to ‘matground’ adaptations tied, in turn, to the prevalence of organically bound substrates in shallow and energetic marine settings. Moreover, although these distinctive ecological strategies were implemented by Ediacara taxa of unresolved affinity, they are also characteristic of younger animal-dominated communities of the Phanerozoic. The late Ediacaran emergence of these strategies may therefore have been pivotal to the subsequent radiations of the Cambrian. In this light, the Ediacaran and Cambrian Periods, although traditionally envisioned as separate worlds, may have been part of an ecological and evolutionary continuum.
