Forbidden fruits in the Garden of Ediacara
статья в журнале
(ИНГГ СО РАН)
дата публикации: 2016
The expulsion of jellyfish from the "Garden of Ediacara", as described by Adolf Seilacher, has challenged the "gelatinous ocean" stereotype; however, not all discoidal fossils can be interpreted as holdfast structures, sandy skeletons of benthic organisms, microbial colonies, fungal fairy rings, or erosional scratch circles. Here I describe a late Ediacaran (550 Ma) medusiform organism, Bjarmia cycloplerusa gen. et sp. nov., preserved as a composite mould in a steep crescentic erosional scour cast in fine-laminated sandstone from the Erga Formation in the Southeast White Sea area. Biostratinomic features point to an allochthonous burial of a bowl-shaped body as it trapped mud pebbles when it was suspended in a sediment-laden flow. An unprecedented range of preserved characters, including moulds of a coronal and longitudinal muscles, suggests affinities with scyphomedusae. The organism is reconstructed as a coronate-like jellyfish, with numerous pedalia separated one from another by deep radiating slits, four deep subgenital pits in the floor of the subumbrella, and a skirt of poorly differentiated tentacle-like structures surrounding the large four-cornered mouth opening. Rhopalia and marginal lappets are not preserved in the specimen.
первоисточник: Palaontologische Zeitschrift