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1 January 2020 Lifestyle of the Octoradiate Eoandromeda in the Ediacaran
Ye Wang, Yue Wang, Feng Tang, Mingsheng Zhao, Pei Liu
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Abstract

The octoradiate Eoandromeda Tang et al. from the Ediacaran of South China and South Australia is poorly understood and there are different interpretations of its morphology and paleoecology. The carbonaceous compression known as Eoandromeda, which is collected in black shales of the upper Doushantuo Formation in northeastern Guizhou, South China, shows various patterns and complex structures. Eoandromeda is interpreted as an umbrella-shaped metazoan, with a dome-shaped polar structure on the top of its body, eight dextrally spiraling arms and tapering skirts. The spiral arms are differentiated into a main segment consisting of rigid and thick masses and a distal segment consisting of flexible and thin masses. Thus, we consider that the spiral arms may have consisted of gelatinous masses and primarily grew in their distal segments (approximately the tapering skirts). The numerous feather-like structures on the platy spiral arms are regularly arranged into two longitudinal rows. We believe that Eoandromeda lived in a primitive “Seabed Grassland” with an abundance and diversity of macroalgae and was capable of swimming in the water column by flapping its feather-like structures. Based on measurements of the maximum diameter of the disk-shaped compression and the maximum width of the spiral arms, Eoandromeda can be divided into a juvenile stage (< 10 mm diameter) that has not been found, an adult stage (10–30 mm diameter) with a high growth rate in the width of the spiral arms, and a senescent stage (> 30 mm diameter) with a slow growth rate in the width of the spiral arms. Fully grown Eoandromeda, with thick and rigid spiral arms, may have mostly stayed on the sediment surface, temporarily swimming to seek new habitat or prey. The juveniles, better swimmers, may have had a soft body with soft and thin arms, unlikely to be preserved, and may have been easily transported by water currents.

© by the Palaeontological Society of Japan
Ye Wang, Yue Wang, Feng Tang, Mingsheng Zhao, and Pei Liu "Lifestyle of the Octoradiate Eoandromeda in the Ediacaran," Paleontological Research 24(1), 1-13, (1 January 2020). https://doi.org/10.2517/2019PR001
Received: 14 May 2018; Accepted: 26 January 2019; Published: 1 January 2020
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KEYWORDS
metazoan
Paleoecology
South China
swimming ability
Wenghui biota
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