CHITDB: a database for documenting and analysing diversification of Ordovician–Silurian chitinozoans in the Baltic region

Abstract

Chitinozoans are a key group in Ordovician and Silurian biostratigraphy, and the Baltic region hosts some of the largest collections of these microfossils in the world. Here, we present an online database – ‘CHITDB’ – for documenting and analysing the distribution of chitinozoans in the Baltic region. The system is integrated with the Estonian geocollections database and includes a public query portal (<http://chitinozoa.net>), which allows browsing and searching for chitinozoan taxa, samples, sections, references and SEM images, downloading raw data by sections, and generating range charts, summary reports and CONOP9 input files. The chitinozoan database holds currently over 35000 occurrence records of 300 chitinozoan taxa from 6400 micro‐palaeontological samples and 100 sections. Quantitative stratigraphical analysis of this data set enabled compilation of the highest resolution chitinozoan diversity curves through the Ordovician and Silurian to date, and assessment of the rates of evolutionary changes. The new model incorporates K‐bentonite and carbon isotope data that help to constrain time relationships between bioevents and environmental changes. The highest chitinozoan diversity in the Baltic region is encountered in late Darriwilian to mid‐Katian and in the Telychian, when the standing diversity reached 30–35 species. Overall, the latest Ordovician and Silurian faunas show more dynamic diversity patterns, with higher extinction and origination rates, than was typical for most of the Ordovician Period.

Contextualizing the Onset of the Great Ordovician Biodiversification Event

“…The CHITDB, the Chitinozoan Database, has captured detailed range data for these Ordovician and Silurian microfossils from the Baltic region (Hints et al . ); analysis of the database demonstrates a diversity hike during the Darriwilian to middle Katian and subsequently during the Telychian. Servais et al .…”

Llandovery microfossils and microfacies of the Hýskov section, Prague Basin

“…The diversity of the chitinozoan assemblage appears to be higher than previously reported by Dufka (1992), containing no less than eight different species. This interval represents the start of the rapid diversification of chitinozoans following the end-Ordovician extinction, and then by a slow recovery period (Paluveer et al 2014, Hints et al 2018. Biostratigraphically, the assemblage corresponds best to the C. alargada Biozone, lacking elements from the under-and overlying zones, and providing additional biostratigraphic constraint for the section.…”

Early and early Middle Ordovician chitinozoans from the Baldone drill core, central Latvia

“…In the Baltic region, Ordovician chitinozoans have been studied in the pioneering works of Alfred Eisenack since the 1930s (see Eisenack 1976 for references) and by many subsequent authors (e.g. Laufeld 1967;Obut 1973;Grahn 1980Grahn , 1982aGrahn , 1982bNõlvak 1980Nõlvak , 2010Wrona 1980;Schallreuter 1981;Obut 1995;Tammekänd et al 2010;Grahn & Paris 2011;Hints et al 2011Hints et al , 2018Nõlvak et al 2019;Liang et al 2022). These studies have resulted in some of the largest collections and distributional data sets worldwide.…”