Brachiopod-dominated communities and depositional environment of the Guanshan Konservat-Lagerstätte, eastern Yunnan, China

Abstract

The Guanshan Biota is an unusual early Cambrian Konservat-Lagerstätte from China and is distinguished from all other exceptionally preserved Cambrian biotas by the dominance of brachiopods and a relatively shallow depositional environment. However, the faunal composition, overturn and sedimentology associated with the Guanshan Biota are poorly understood. This study, based on collections through the best-exposed succession of the basal Wulongqing Formation at the Shijiangjun section, Wuding County, eastern Yunnan, China recovered six major animal groups with soft tissue preservation; brachiopods vastly outnumbered all other groups. Brachiopods quickly replace arthropods as the dominant fauna following a transgression at the base of the Wulongqing Formation. A transition from a botsfordiid-, eoobolid- and acrotretid- to an acrotheloid-dominated brachiopod assemblage occurs up-section. Four episodically repeated lithofacies reveal a relatively low-energy, offshore to lower shoreface sedimentary environment at the Shijiangjun section, which is very different from the Wulongqing Formation in the Malong and Kunming areas. Multiple event flows and rapid obrution are responsible for faunal overturn and fluctuation through the section. A detailed lithofacies and palaeontological investigation of this section provides a better understanding of the processes and drivers of faunal overturn during the later phase of the Cambrian Explosion.Supplementary material: Composition and comparison of the Malong Fauna and the Guanshan Biota is are available at: https://doi.org/10.6084/m9.figshare.c.5080799

Evolution and diversity of biomineralized columnar architecture in early Cambrian phosphatic-shelled brachiopods

“…The homology of the columnar architecture in early linguliforms outlines a clear picture, most likely representing a continuous transformation between the Lingulida (Eoobolidae and Lingulellotretidae) and Acrotretida. Two groups that represent a major component of early Cambrian benthic communities (Chen et al, 2021; Claybourn et al, 2020; Topper et al, 2015; Zhang et al, 2008; Zhang, 2018; Z. L. Zhang et al, 2020a). The possible occurrence of this shell architecture within the family Obolidae cannot be discounted, as detailed information on the possible columnar shell structures in early Cambrian representatives such as, Kyrshabaktella and Experilingula are poorly known (Cusack et al, 1999; Streng et al, 2007; Williams, 1977).…”

“…Among them, the phosphatic-shelled brachiopods are some of the most common animals in early Cambrian faunas (Harper et al, 2017). With a high fidelity of preservation and high abundance of biomineralized shells in the fossil record, their morphological disparity, diversity of shell structures and growth patterns, together with ecological complexity are preserved in great detail (Chen et al, 2021; Claybourn et al, 2020; Topper et al, 2018; Zhang, 2018; Z. L. Zhang et al, 2020a, 2021b).…”

Brachiopods from the Latham Shale Lagerstätte (Cambrian Series 2, Stage 4) and Cadiz Formation (Miaolingian, Wuliuan), California

“…The abundant olenellid trilobites and hyolithids in this fauna (Fig. 6) (Mount, 1980), together with brachiopod species commonly seen in early Cambrian time, comprise important components of the CEF, like the Chengjiang and Guanshan Lagerstätten, which were dominated by trilobites and nonarticulated brachiopods (Zhao et al, 2010; Chen et al, 2018, 2021).…”

New multipodomerous appendages of stem-group euarthropods from the Cambrian (Stage 4) Guanshan Konservat-Lagerstätte

“…The Wulongqing Formation of eastern Yunnan hosts the Guanshan Biota, which is known from over 10 localities [27,28]. The Wulongqing Formation comprises mud, silt and sandstones [27,29]. Exceptionally preserved fossils are most commonly found in mudstone units, which probably represent rapid burial events [27,30].…”

“…Exceptionally preserved fossils are most commonly found in mudstone units, which probably represent rapid burial events [27,30]. Importantly, sedimentological and trace fossil evidence suggests that the levels hosting exceptionally preserved fossils were probably deposited in a relatively shallower setting compared with all other Cambrian Konservat-Lagerstätten, including the geographically close Chengjiang (Stage 3) and Kaili (Wuliuan) biotas [27,29,31,32]. Euarthropods dominate the biodiversity in the Guanshan Biota [27,33] and are known alongside taxa from numerous other animal groups including annelids, brachiopods, echinoderms, lobopodians and sponges, as well as possible algae [27,28,33].…”