Damaged Dickinsonia specimens provide clues to Ediacaran vendobiont biology

Abstract

Recently reported specimens of the enigmatic Ediacaran fossil Dickinsonia from Russia show damage and repair that provides evidence of how they grew, and of their biological affinities. Marginal and terminal areas of wilting deformation are necrotic zones separating regenerated growth, sometimes on two divergent axes, rather than a single axis. Necrotic zones of damage to Dickinsonia are not a thick scar or callus, like a wound or amputation. Nor are they smooth transitions to a regenerated tail or arm. The wilted necrotic zone is most like damage by freezing, salt, or sunburn of leaves and lichens, compatible with evidence of terrestrial habitat from associated frigid and gypsic paleosols. Dickinsonia did not regrow by postembryonic addition of modules from a subterminal or patterned growth zone as in earthworms, myriapods, trilobites, crustaceans, and lizards. Rather Dickinsonia postembryonic regrowth from sublethal damage was from microscopic apical and lateral meristems, as in plants and lichens. Considered as fungal, Dickinsonia, and perhaps others of Class Vendobionta, were more likely Glomeromycota or Mucoromycotina, rather than Ascomycota or Basidiomycota.

Reconsideration of the Ediacaran problematicum Aulozoon

“…Furthermore, the Ediacaran forearc basin of Newfoundland is on continental granitic basement, not deep-sea pillow basalts (Retallack, 2014). Dickinsonia looks like no animal (Seilacher, 1992), and its fractal system of isomers is similar to those of pseudomeristematic growth in crustose lichens (Retallack, 1994(Retallack, , 2007(Retallack, , 2022b.…”

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“…While there are not many fossil chemicals, Bobrovskiy et al (2018) identified several monoaromatic steroids in the organically preserved, Ediacaran macrofossil, Dickinsonia . This is a fossil genus recorded from South Australia, the Russian White Sea, Russian Urals, Ukraine, India, and China (Retallack, 2022). These findings confirm Dickinsonia as the oldest macroscopic animals in the rock record.…”