Ichnology, palaeoenvironment, and ecosystem dynamics of the Early Cambrian (Stage 4, Series 2) Guanshan Biota, South China

Abstract

The Guanshan Biota of the Wulongqing Formation (Cambrian Series 2, Stage 4) is a typical Burgess Shale‐type Lagerstätte, containing not only a diverse assemblage of exceptionally preserved body fossils but also abundant, sophisticated trace fossils. Detailed ichnological study of the lower part of the Wulongqing Formation from the Longbaoshan and Xinglongcun sections in the Kunming area, Yunnan, South China, reveals the presence of 17 ichnospecies, including Aggregatella isp., Cruziana isp., Didymaulichnus lyelli, Diplichnites isp., Guanshanichnus glockerichnoides, Monomorphichnus isp., Palaeophycus isp., Planolites beverleyensis, Planolites montanus, Planolites isp., Psammichnites isp., Phycodes isp., Skolithos verticalis, Thalassinoides isp., Treptichnus pedum, and two types of non‐specific coprolites. These trace fossils represent burrowing or locomotion behaviours of arthropods and vermes, and belong to the Cruziana and Skolithos ichnofacies. As the outcrop at the Xinglongcun section is not well exposed, a systematic sedimentary study was conducted at the Longbaoshan section. The Guanshan ichnofauna in the lower Wulongqing Formation at the Longbaoshan section occur in fine‐grained siliciclastic rocks with wavy bedding, lenticular bedding, and wrinkle structures, reflecting a tidal flat environment. The abundance of diverse trace fossils in the tidal flat facies indicate that many taxa, mostly arthropods, were able to colonize the very shallow marine environments, supporting the landward expansion of the Early Cambrian ecosystems.

Geometric morphometric assessment of Guanshan trilobites (Yunnan Province, China) reveals a limited diversity of palaeolenid taxa

“…The Guanshan Biota are preserved in the Wulongqing Formation (Cambrian Series 2, Stage 4; Figure 1) and are therefore slightly younger than the Chengjiang Biota (Cambrian Series 2, Stage 3) (Hu et al, 2010(Hu et al, , 2013(Hu et al, , 2017Liu et al, 2012Liu et al, , 2016Ding et al, 2020). The palaeolenid trilobites studied here were collected from three sections of the Wulongqing Formation: the Huanglongqing, Longbaoshan, and Xinglongcun sections.…”

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

“…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].…”

Bioturbation of Thalassinoides from the Lower Cambrian Zhushadong Formation of Dengfeng area, Henan Province, North China

“…There are numerous modern examples of thalassinid shrimps found in burrows with the characteristics of Thalassinoides (Glaessner 1957;Beikirch and Feldmann 1980). During the Paleozoic, arthropods, sea anemones and worm-like bioturbators are probable candidates for producers of Thalassinoides (Ekdale and Bromley 2003;Cherns et al 2006;Ding et al 2020). No matter in which geological period, the Paleozoic to modern time, all of Thalassinoides have same characteristics and have a three-dimensional boxwork of branched cylindrical burrow system sometimes interconnected by vertical shafts.…”