The bias types and drivers of the Furongian Biodiversity Gap

Abstract

The Furongian Biodiversity Gap (FBG), which is well known as the biodiversity minimum between the Cambrian Explosion (CE) and the Great Ordovician Biodiversification Event (GOBE), has recently been the subject of much research seeking to identify the onset of the GOBE. Whether the FBG is a real evolutionary trend or a bias gap due to insufficient sampling has been controversial. In this study, a systematic investigation of the relationships between fossil sampling intensity, spatial extent, and biodiversity during the Cambrian and Ordovician, using data from the Paleobiology Database (PBDB) is carried out to gain a better understanding of this lowstand in biodiversity. Special focus is placed on the types of bias and the internal and external bias drivers affecting the FBG. The results show that external factors such as a low degree of research interest, socioeconomic influence, and unevenness of research intensity have led to limited fossil sampling and research, which have interacted with internal factors (biological and geological preservation) and led to biases in understanding the FBG. The bias types of the FBG are multi-dimensional. Temporally, there are fewer fossil collections from the Furongian. Geographically, the lack of fossil data at middle and high latitudes results in a low geographical extent and unevenness of the spatial distribution of Furongian fossils. Taxonomically, trilobites and conodonts, which are of high biological importance, are the main studied fossil groups from the Furongian. Lithologically, widely distributed shales deposited in the Furongian and their biotas are not sufficiently studied. Moreover, the above analysis of the FBG based on the PBDB is inherently affected by database bias. The FBG is interpreted as a collection failure which requires more fossil data and methodological innovation for a better and comprehensive interpretation.