Chitinozoan study: review and prospect

Chitinozoans are one of the vital groups of microfossils in the Palaeozoic ocean. Because of their rapid evolution at species level and high abundance in different types of sediments, chitinozoans have been used as one of the most essential and valuable tools in Ordovician and Silurian biostratigraphy. Related research results have provided crucial insights into major geological, environmental, and biological events. However, with the development in modern palaeontology and the accumulation of data during the last decades, chitinozoan study has been experiencing a period of stagnation. First, due to limited techniques applied and lacking standard research criteria in early chitinozoan study, poorly presented images and simple descriptions have resulted in confusion on the taxonomy of some early established chitinozoan taxa, which in turn has a negative influence on the chitinozoan systematics, as well as further study that relies on taxonomy, preventing a better survey of major biological events such as the Great Ordovician Biodiversification Event. Second, digitalisation and visualisation of palaeontological data have become two of the most important and hottest subjects in palaeontology. However, chitinozoan research in this aspect is proceeding quite slowly. Until now, the lack of an efficient database collecting and analysing global chitinozoan data has seriously weakened the usage of the chitinozoan data and has failed to provide data support on the study of chitinozoan macroevolution, biostratigraphy, palaeobiogeography, and palaeoecology. Third, recent studies have provided new insights into the biological affinity of chitinozoans, albeit with some controversies. New evidence is required to further discuss this issue. To effectively facilitate chitinozoan studies, we suggest designing and constructing an open-access chitinozoan database for all the 1311 documented chitinozoan species on the Geobiodiversity Database platform. This database will present combined information such as taxonomy, morphological features, high-resolution images, locality data, formations, ages, section information, and related references. Registered users can search, input, revise, import and analyse the data. In the meantime, revisions on poorly documented chitinozoan records from China and the Baltic will be carried out as a first step to make the data more reliable. Advanced imaging techniques, such as Near-Infrared Microscopy, focused ion beam scanning electron microscopy, field emission scanning electron microscope, and X-ray computed micro-tomography will be applied to update the morphological information of all poorly imaged types, including their interior structures and ultrastructures. Revisions on controversial chitinozoan records from the Ordovician as well as those from the Silurian and the Devonian in other areas will be carried out in the future. Creating a global chitinozoan database and revising poorly presented chitinozoan records based on extensive data analysis and high-resolution imaging techniques will be a significant advance for the field. This will substantially facilitate the study of the morphology, microevolution, biostratigraphy, palaeogeography and palaeoecology of chitinozoans. This project will bring chitinozoan research into a new era and will be an essential case study to show how far basic research can go with the support of big data and advanced techniques.