The 19th International Congress on the Carboniferous and Permian (19th ICCP) was hosted by the University of Cologne, Germany, from July 29th to August 2nd, 2019. The inspiring meeting, visited by exactly 200 scientists from 27 countries, integrated a wide range of topics contributing to a continuously growing inherent understanding and holistic view of the Carboniferous and Permian World (Herbig 2020; Herbig et al. 2021a). The congress series rooted from the famous “Heerlen Congress 1927” that took place in the formerly important coal mining district of South Limburg, southeastern Netherlands, and initiated the global standardization of Carboniferous chronostratigraphy. After three further congresses at Heerlen in the years 1935, 1951, and 1958, the congress series was named “Congrès International de Stratigraphie et de Géologie du Carbonifère” until the Permian was added in the 12th congress in Buenos Aires in 1991 (not Cracow, 1995, as erroneously stated by Herbig et al. 2021a). Since the Cracow congress, the name was shortened to “International Congress on the Carboniferous and Permian”, besides semantical shortening certainly a tribute to the progressive widening scientific topics. However, since the earliest beginning, biostratigraphy inevitably based on sound palaeontological research is of special interest, as also seen in the wealth of corresponding contributions at the 19th ICCP. In this context, we like to stress that all ratified Palaeozoic and Mesozoic GSSPs of the International Chronostratigraphic Chart are based on the phylogenetic first appearances of organisms, in spite of recent criticism by Davydov (2020) who argued for usage of volcanic ash beds as primary chronostratigraphic markers and underlined this view with examples from the Carboniferous and Permian, including the Devonian–Carboniferous boundary and the Permian–Triassic boundary.

Nonetheless, it is our honour to present this thematic issue containing eight palaeontological contributions presented at the 19th ICCP as well as a supplementary paper. The contributions are mostly devoted to taxonomy and biostratigraphy, in part related to the quest for GSSPs in the Carboniferous and Lower Permian. In consequence, the contributions deal with the most important guide fossils—conodonts, smaller foraminifers, fusulinids, and ammonoids. Further contributions deal with taxonomy of tabulate corals, anatomical ultrastructures of palynomorphs, stratigraphic correlation, palaeobiogeography, and carbonate microfacies. Regionally, the papers include studies from Turkey, Iran, Ukraine, and Kazakhstan; they include different parts of Russia including its Far East and bridge to the western side of North America in British Columbia (Canada).

However, our joy about completing the present thematic issue is clouded by the grief for our friend and colleague George Sevastopulo, who passed away in mid-September 2021, and to whom we dedicate this issue. Wyse Jackson and Aretz (2022) contributed the obituary herein. George was a distinguished researcher of Carboniferous stratigraphy and palaeontology. He actively contributed to the 19th ICCP as first author and co-author with two oral presentations (Pointon et al. 2019; Sevastopulo et al. 2019), and took part in the post-congress field trip to the Mississippian Kulm Basin of the Rhenish Mountains. Finally, his co-authored presentation on uranium-lead dates from Livian (middle Viséan) bentonites of the Namur-Dinant Basin, Belgium was printed last summer in the special Issue “19th International Congress on the Carboniferous and Permian, Cologne 2019. Stratigraphic contributions” (Pointon et al. 2021), and only some two and a half months before he deceased.

The articles in the present issue are arranged in stratigraphical order. The stratigraphically oldest one by Nikolaeva et al. (2022) contributes to the discussion on the redefinition of the Devonian–Carboniferous boundary. This issue was extensively discussed at the 19th ICCP and recently deepened in a volume edited by Aretz and Corradini (2021). Nikolaeva et al. provide a detailed description of the mostly shallow-water, mixed carbonate-siliciclastic Berchogur (Birshogyr) sections in the Mugodzhary (Mugalzhary) Mountains in western Kazakhstan based on previous and supplemented by new data, and illustrate its varied fossil content. Of special interest within the finely subdivided biostratigraphic succession is the co-occurrence of ammonoids of the Acutimitoceras Genozone, the conodont Siphonodella sulcata, and the foraminifer Tournayellina pseudobeata that indicate the earliest Carboniferous faunal diversification. In general, recognition of siliciclastic–carbonate cycles and combined multibiostratigraphy enable a very close approximation of the Devonian–Carboniferous boundary, in spite of the absence of the conodont Protognathodus kockeli which is proposed as another index for the boundary, and missing of the typical “Hangenberg lithologies” developed in its type region in the Rhenish Mountains, Germany.

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The presentation of the lower Famennian to latest Tournaisian conodont biostratigraphy of the Chelcheli section in the eastern Alborz Mountains (North Iran) by Bahrami et al. (2021) supplements the contributions from the 19th ICCP. Almost 50 conodont species from 15 genera enabled recognition of 15 conodont zones in a supposedly continuous, predominantly calcareous shallow-water succession. Comparable with the Berchogur sections presented above, the index species Protognathodus kockeli and Protognathodus kuehni and also Siphonodella sulcata do not occur at the Devonian–Carboniferous boundary. In contrary, the characteristic “Hangenberg lithologies” are developed which are not known from other Devonian–Carboniferous boundary sections in Iran. Unfortunately, the record of Tournaisian conodont zones remains meagre. It is restricted to the undifferentiated middle–upper Tournaisian Siphonodella isosticha-Upper Siphonodella crenulata and Gnathodus typicus zones and the overlying latest Tournaisian Scaliognathus anchoralis-Doliognathus latus Zone.

Ohar (2022) deals with taxonomic description and biostratigraphic distribution of Tournaisian and lower Viséan tabulate corals from the Donets Basin, eastern Ukraine, which allow a fine insight into this less known faunal group. He differentiates eleven species, one of them new, belonging to six genera from four families. Faunal changes are congruent to those observed in rugose corals and at least in certain cases are connected to sea-level changes. Of special interest is the discussion and preliminary description of the historical type material of Syringopora ramulosa Goldfuss, type species of the genus, and Syringopora reticulata Goldfuss, both housed at the Goldfuß-Museum of the University of Bonn, Germany.

Smaller calcareous foraminifers underwent explosive radiation during the Mississippian. They are the most important stratigraphic index fossils in calcareous shallow-water deposits and enable Palaeotethys-wide correlations, in spite of some necessary taxonomic revisions and uncertainties on locally delayed first occurrences or longer ranging refugee taxa. Kulagina (2021) describes the middle to upper Viséan succession of the Sikasya River Valley in the South Urals, which is mostly calcareous in its lower part but contains some important dolomitic intercalations in the upper Viséan and lower Serpukhovian. She describes five foraminiferal units and their correlation with the Belgian standard zonation as well as with the zonation of the Russian Platform. The still debated Viséan–Serpukhovian boundary is approximated by the index foraminifer Eostaffellina decurta.

Akbaş and Okuyucu (2022) present a detailed biostratigraphic study devoted to the fusulinid biozonation of the Bashkirian–Moscovian successions from the Hadim Nappe in the central Taurides, southern Turkey. Based on rich, amply illustrated fusulinid assemblages, they defined four first occurrence zones for each of the Bashkirian and Moscovian stages. This contribution from a less-studied region closes an important gap in the knowledge of Palaeotethyan fusulinid faunas and enables correlation throughout the realm, from northern Spain across the Donets Basin, the Russian Platform, and Southern Urals to central Asia and southern China, as well as to Iran. Particularly close connections exist with the Russian Platform and enable correlation with the substages/horizons of the Russian regional chronostratigraphic subdivisions.

A second contribution on the Donets Basin within this special issue analyses conodonts from the Moscovian–Kasimovian boundary interval in the Kalinovo section which is one of the most continuous successions in eastern Ukraine. Nemyrovska (2022) recognizes two evolutionary events in conodont history. The lower one with the income of new species of Swadelina results in the necessity to shift the Moscovian–Kasimovian boundary in the Carboniferous Stratigraphic Scale of the Ukraine according to the valid definition of the Moscovian–Kasimovian boundary. A second prominent conodont event upsection is characterized by the income (FOD) of the conodont Idiognathodus sagittalis and a number of new species of the genus that are described and figured in open nomenclature. The potential of this index conodont for future definition of the Moscovian–Kasimovian boundary as well of some further conodonts is discussed; however, correlation of Palaeotethyan and North American conodont faunas is strongly hampered by provincialism of the two realms.

Three papers of this special issue present results from the Permian. In a very detailed analysis Filimonova and Isakova (2022) describe four new species of smaller foraminifers from strata close to the Artinskian–Kungurian boundary from localities in the Middle and Southern Urals. Main focus is the Mechetlino Quarry section which is a potential GSSP candidate for the base of the Kungurian, the uppermost Cisuralian (Lower Permian) stage. The new, highly variable species of the genera Hemigordius and Pseudoammodiscus are very similar in equatorial sections, in number of whorls and size, but discrimination is very well supported in binary diagrams. New species of the genus Nodosaria show a multi-layered, poly- or plesiomonolamellar wall, a feature that might be a good marker of the upper Artinskian close to the Artinskian–Kungurian boundary.

In spite of a high number of presentations on Carboniferous and Permian plants at the 19th ICCP, only a single contribution could be obtained for this issue. This is a sophisticated palynological study from the Middle Permian (Roadian–Wordian) of the eastern part of the Russian Platform by Foraponova (2022). She describes for the first time in situ pollen of Permotheca sardykensis Zalessky, a morphotaxon for pollen organs, now generally considered to belong to peltasperm seed ferns, a supposedly basal gymnosperm group. The author also compares pollen grains of other Permotheca species. Marked differences might indicate that Permotheca is a heterogenous morphotaxon of several similar, but unrelated pollen organs and doubts remain that all Permotheca species belong to the Peltaspermales.

Finally, Nestell and Nestell (2021) present a fascinating palaeobiogeographic connection between southern British Columbia (western Canada), South Primorye (Russian Far East), and Japan. The results are based on the taxonomic analysis of in part exotic fusulinids, most probably of early Capitanian (late Guadalupian, late Middle Permian, respectively) age from the Cache Creek Terrane, among those four new species. Moreover, 43 taxa of smaller calcareous foraminifers are listed and illustrated. The fusulinid genera Sichotenella and Wutuella were never reported from North America before, but like further fusulinids and smaller foraminifers belong to taxa that are known from the Primorye area, northeastern China and Japan. Further faunal elements also show relations to the autochthonous Western Hemisphere fauna of the Delaware Basin of West Texas.

This is the third and last issue of contributions resulting from the 19th ICCP. A first issue, published in Newsletters on Stratigraphy 54(3), assembled a set of seven papers dealing with chronostratigraphy, biostratigraphy, and non-marine lithostratigraphy (Herbig et al. 2021b). A second issue was published by colleagues of the Geological Survey of North Rhine-Westphalia (Geologischer Dienst Nordrhein-Westfalen) in ZDGG, Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 172(3). It contains nine papers of the ICCP 2019 session “Mississippian carbonate rocks in North-West Europe—reservoir for deep geothermal energy” and supplementing contributions (Arndt and Salamon 2021).

Moreover, the scientific achievements of the 19th ICCP were documented in the abstract volume that contains 179 contributions, up to two pages long, mostly including a key figure and selected references (Hartenfels et al. 2019), and in an extensive, fully coloured field guide volume (Herbig et al. 2019) with description of six field trips to the Carboniferous and Permian of Germany, adjacent Belgium, and to the Carnic Alps and Karavanke Mountains along the borders of Austria, Italy, and Slovenia. A general report on the congress was given by Herbig (2020). With the end of the activities on the 19th ICCP, it is now time to look forward and to pass the baton to the 20th International Congress on the Carboniferous and Permian that will take place in Toulouse, Southern France.