User:Colin Douglas Howell/Nobu Tamura gallery - Animals of the Ediacaran biota

Animals of the Ediacaran biota

These are depictions by Nobu Tamura of animals (or organisms believed to be animals) from the Ediacaran biota that have been found in South Australia, Russia, and elsewhere. They lived around 560 to 540 million years ago during the late Ediacaran period, the first period in Earth history known to have complex multicellular organisms, just before the Cambrian explosion when most known animal phyla appeared. All of these Ediacaran creatures lived on the sea floor, and all had soft bodies; mineralized body structures like shells and exoskeletons did not evolve until the Cambrian.

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  Charnia masoni, a frond-like rangeomorph organism around 15 cm (6 in) long that has been found in England, Australia, Russia, and Newfoundland. Charnia lived in deep waters out of the reach of sunlight. It is not known whether rangeomorphs like Charnia were animals or belonged to some other kingdom of life, but a new animal phylum Petalonamae has been suggested for them and certain other Ediacaran creatures; this would be a sister group to the Eumetazoa (the group of all animals except sponges).
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  Obamus coronatus, a doughnut-shaped animal of unknown type from South Australia. Obamus was tiny, less than 1 cm (¹⁄₂ in) across, and was only discovered in 2018.
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  Tribrachidium heraldicum, a dome-shaped trilobozoan from South Australia which grew from around 3 mm (¹⁄₈ in) up to 5 cm (2 in) in size. Trilobozoans are a phylum of Ediacaran disc-like animals with tri-radial symmetry that may have been related to the cnidarians (corals, jellyfish, sea anemones, and hydras).
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  Haootia quadriformis, a cnidarian polyp from Newfoundland about 5 cm (2 in) across. Haootia is the earliest animal in which muscle fibers have been clearly identified. It's not known which class of cnidarians Haootia was closest to.
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  Dickinsonia costata, a possible bilaterian animal that has been found in South Australia, Russia, and Ukraine. Specimens vary in length from a few millimeters up to over a meter in extreme cases. Dickinsonia is believed by most to be an animal, but its relationship with other animals is debated. Bilaterians are the group of animals with bilateral symmetry (sometimes only in larval form, as with the echinoderms) that were derived from a single ancestor; they comprise the great majority of animals. Dickinsonia and similar segmented Ediacaran animals have been proposed to be from a phylum Proarticulata that branched off very early from the bilaterians. Since fossil trackways (Epibaion) have been found associated with Dickinsonia, it is believed to have moved over the sea floor to feed, as depicted here with the track in the sediment to the right. There is no evidence that Dickinsonia had a mouth or gut; it may have fed by absorbing nutrients through its bottom surface.
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  Parvancorina minchami, a probable bilaterian which has been found in South Australia and Russia. Its average size is around a centimeter or two (half an inch to an inch). At first Parvancorina was thought to be a proto-arthropod, from a superficial resemblance to the forms of some early trilobites, but that has since been rejected. It has some similarities to other Ediacaran animals which may be mollusc relatives.
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  Kimberella quadrata, a bilaterian from South Australia and Russia. Kimberella grew from a few millimeters up to around 15 cm (6 in) long. It had a muscular "foot" somewhat like a slug's, a tough but flexible non-mineralized carapace, a fringe surrounding the body which might have acted as a gill, and a toothed frontal proboscis which it used to scrape food from microbial mats. Kimberella has been proposed as a possible proto-mollusc or mollusc relative, but this is as yet uncertain.