Morphology and Nomenclature of Barsassia (Lycopsida) from the Middle Devonian of West Junggar, Xinjiang, China.

Ruiwen Zong,Honghe Xu,Bingcai Liu,Kai Wang,Yi Wang

doi:10.3390/plants10122631

Abstract

Morphology and nomenclature are essential issues of botany, in which both extant and fossil plant taxa follow the same nomenclature code. Devonian (419.2–358.9 Ma) herbaceous lycopsid Barsassia, one of the earliest coal-forming plants in geological history, possesses a characteristic, easily recognized, step-like stem and has been thought to be an index fossil for dating and correlating the Middle Devonian strata, especially those in the paleoblocks of Siberia, Kazakhstan, Xinjiang, and North China. Here, we systematically study the Devonian lycopsid Barsassia in terms of its morphology and nomenclature, based on the new materials from the Middle Devonian Hujiersite Formation of West Junggar, Xinjiang, China, and the International Code of Nomenclature for algae, fungi, and plants (Shenzhen Code). Barsassia ornata is determined as the type species of the genus, and a neotype is designated for that name. Barsassia ornata consists of fan- or rectangular-shaped leaves with awl-shaped or finger-like distal tips. Its leaves are pseudo-whorls and imbricately arranged on the stem surface forming distinct step-like structure.

Highlights

BergThe Devonian Period (419.2–358.9 million years ago) is critical for the origin and the radiation of terrestrial vascular plants
Much terrestrial organic carbon produced from Devonian Barsassia and other lycopsids was buried and formed the earliest coal seams [14] and potential petroleum reserve, e.g., only 80–100 cm thick carbonaceous beds in the Middle Devonian of Junggar, Xinjiang [12,13,15,16], Kuznetsk Basin, southwestern Siberia [17,18], and Luquan, Yunnan, southern China [14,19]
Zalessky (1933) [17] firstly reported Barsassia ornata based on two specimens from the Middle Devonian of Barsas, Siberia

Summary

Introduction

BergThe Devonian Period (419.2–358.9 million years ago) is critical for the origin and the radiation of terrestrial vascular plants. Devonian plant fossil records show a critical and distinctive window for understanding the plant and paleoenvironment evolution [7]. The herbaceous lycopsid Barsassia has been thought to be an important fossil taxon for dating and correlating the Middle Devonian strata, especially those in Siberia, Kazakhstan, Xinjiang, and North China paleoblocks [8,9,10,11,12,13], for its characteristic and recognized step-like stem. Much terrestrial organic carbon produced from Devonian Barsassia and other lycopsids was buried and formed the earliest coal seams [14] and potential petroleum reserve, e.g., only 80–100 cm thick carbonaceous beds in the Middle Devonian of Junggar, Xinjiang [12,13,15,16], Kuznetsk Basin, southwestern Siberia [17,18], and Luquan, Yunnan, southern China [14,19].

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Discussion

Conclusion