The Ediacaran frondose fossil Arborea from the Shibantan limestone of South China

Xiaopeng Wang,Bin Wan,Zhe Chen,Ke Pang,Chuanming Zhou,Shuhai Xiao,Xunlai Yuan

doi:10.1017/jpa.2020.43

Abstract

AbstractBituminous limestone of the Ediacaran Shibantan Member of the Dengying Formation (551–539 Ma) in the Yangtze Gorges area contains a rare carbonate-hosted Ediacara-type macrofossil assemblage. This assemblage is dominated by the tubular fossil Wutubus Chen et al., 2014 and discoidal fossils, e.g., Hiemalora Fedonkin, 1982 and Aspidella Billings, 1872, but frondose organisms such as Charnia Ford, 1958, Rangea Gürich, 1929, and Arborea Glaessner and Wade, 1966 are also present. Herein, we report four species of Arborea from the Shibantan assemblage, including the type species Arborea arborea (Glaessner in Glaessner and Daily, 1959) Glaessner and Wade, 1966, Arborea denticulata new species, and two unnamed species, Arborea sp. A and Arborea sp. B. Arborea arborea is the most abundant frond in the Shibantan assemblage. Arborea denticulata n. sp. resembles Arborea arborea in general morphology but differs in its fewer primary branches and lower length/width ratio of primary branches. Arborea sp. A and Arborea sp. B are fronds with a Hiemalora-type basal attachment. Sealing by microbial mats and authigenic cementation may have played an important role in the preservation of Arborea in the Shibantan assemblage. The Shibantan material of Arborea extends the stratigraphic, ecological, and taphonomic ranges of this genus.UUID: http://zoobank.org/554f21da-5f09-4891-9deb-cbc00c41e5f1

Highlights

Ediacara-type macro-organisms are soft-bodied, morphologically complex eukaryotes that flourished in the last 30 million years of the Ediacaran Period (∼571–539 Ma; Pu et al, 2016; Linnemann et al, 2019)
To contribute to our understanding of Ediacaran frondose fossils, here we provide a systematic description of new arboreomorphs preserved in limestone of the terminal Ediacaran Shibantan Member in the Yangtze Gorges area of South China
Millimeter-scale, clay-rich, crinkled laminae are common in the Shibantan Member. These crinkled laminae have been interpreted as microbial mats (Chen et al, 2013), which have been hypothesized to be an important factor facilitating the preservation of soft-bodied Ediacaran fossils (Gehling, 1999; Callow and Brasier, 2009; Laflamme et al, 2011)

Summary

Introduction

Ediacara-type macro-organisms are soft-bodied, morphologically complex eukaryotes that flourished in the last 30 million years of the Ediacaran Period (∼571–539 Ma; Pu et al, 2016; Linnemann et al, 2019). To contribute to our understanding of Ediacaran frondose fossils, here we provide a systematic description of new arboreomorphs preserved in limestone of the terminal Ediacaran Shibantan Member in the Yangtze Gorges area of South China. These taxa represent the first formal report of Arborea from terminal Ediacaran carbonate facies, and together with possible arboreomorphs from the Khatyspyt Formation in northern Siberia described as Khatyspytia grandis (Fedonkin, 1985; Grazhdankin et al, 2008; Grazhdankin, 2014), they help us to better understand the stratigraphic, ecological, and taphonomic ranges of the Arboreomorpha. Millimeter-scale, clay-rich, crinkled laminae are common in the Shibantan Member These crinkled laminae have been interpreted as microbial mats (Chen et al, 2013), which have been hypothesized to be an important factor facilitating the preservation of soft-bodied Ediacaran fossils (Gehling, 1999; Callow and Brasier, 2009; Laflamme et al, 2011). Similar to the Hamajing Member, dissolution structures, tepees, and Journal of Paleontology 94(6):1034–1050

Materials and methods

Findings

Conclusion