Agassiz’s beautiful illustrated five volume opus “Recherches sur les poissons fossiles” (1833–1843) was the actual beginning for paleoichthyology. He gave, in this publication, the first comprehensive presentation of fossil agnathans and fishes. In the ensuing years, numerous descriptions of forms (mostly from Europe and North America) were published. These were compiled by A. S. Woodward (1889–1901), one of the many excellent paleoichthyologists (from past to present) in Great Britain, in his famous “Catalogue of Fossil Fishes in the British Museum (Natural History)”. The catalogue was compiled so well that it is continuously used by specialists in paleoichthyology.

In Scandinavia after World War I, E. A:son Stensiö founded an important school for paleoichthyology. He and his followers did extremely detailed investigations, with great emphasis on anatomical interpretations. These brought about strong controversies, between the Stockholm and the English-American schools, regarding the interpretation of morphological data and the interrelationships of different groups of agnathans and fishes. Even though the Stockholm school disappeared with the demise of its instigators, the controversy lived longer, and Russian, German and French paleoichthyologists found themselves having to take sides. The English-American school including Australian and Chinese paleoichthyologists dominates the field now.

Between 1960 and 1970 one synopsis in Russian (Obruchev, D. V. (ed.) 1964: Osnovy paleontology, vol. 11: Agnatha, Pisces; 1967: Engl. translation), one in French (Piveteau, J. (ed.) 1964 to 1969: Traité de Paléontologie, vol. 4: 1, Vertébrés, Agnathes; 2, Gnathostomes, Acanthodiens, Placodermes, Elasmobranches; 3, Actinopterygiens, Crosso­pterygiens, Dipneustes) and a shorter one in German (Müller, A. H. 1966: Lehrbuch der Paläozoologie. Band III. Vertebraten. Teil 1. Fische im weiteren Sinne und Amphibien) were published, covering the whole field of paleoichthyology. The Osnovy presents the fishes in a systematic order, whereas the Traité focusses on morphological-anatomical aspects following the Swedish School, of which members compiled part of it. A new version of the fish volume of the Osnovy (Novitskaya, L. I. & Afanassieva, O. B. (eds.), Agnathans and Early Fishes) was published in 2004; it presents selected groups of Paleozoic fishes (Thelodonti, Heterostraci, Osteostraci, and Sarcopterygii [Crossopterygii and Dipnoi]), but is more geographically constrained than the first edition of the Osnovy.

New and young paleoichthyologists have replaced the older well-reputed generation. New findings, especially in remote and less explored regions (Asia, southern continents, and northern and southern polar regions) reveal a great amount of new information about Paleozoic agnathans and fishes. Especially important are the findings in China and Australia because they were accompanied by the emergence of a new group of scientists.

In addition, another event has influenced and will continue to influence paleoichthyology: Willi Hennig’s book “Grundzüge einer Theorie der phylogenetischen Systematik” (1950) translated in 1966 into English (“Phylogenetic systematics”) by R. Zangerl, a contributor to the Handbook. Since the 1970s, revision, verification and/or falsification of the old ideas regarding the interrelationships of agnathans and fishes has ensued. This new approach that began in the 1960s contradicted the approach of the Stockholm School and was refuted by its members, what lead to the demise. The new group of paleoichthyologist in Uppsala, Sweden, is no continuation, in contrary it is a branch of the English tradition of paleoichthyology. Finally, new nondestructive methods like CTscan and Synchrotron X-ray microtomography have revolutionized our ability to interpret internal structures of fossils.

The Handbook of Paleoichthyology summarizes (as far as possible) all known data as a comparison with new findings and for interpretation of interrelationships. The reader will find the most current analyses of interrelationships, sometimes even contrary ones in different volumes.

Each volume deals with the anatomy and the fossil record of agnathans or of a group (class, subclass, etc.) of gnathostome fishes, except volume 10, which deals with one organ of osteichthyan fishes, otoliths or ear stones. The Actinopterygii, one of the two groups of osteichthyan fishes, will be dealt in volumes 8 and 9, where Volume 8 will cover the lower actinopterygians (Volume 8A: basal actinopterygians, Volume 8B: basal neopterygians [Holostei ]) and Volume 9 the Teleostei . Volume 8A had a difficult history; after the first author returned the assignment, Cecile Poplin took over relatively late, and she was not able to finish the manuscript. She turned it over to the editor of the Handbook, who started after finishing the editorship of a Solnhofen book. In addition, Kathryn E. Mickle agreed to help to finalize the manuscript and figures. The first part except the portion on the endocranium, and the bibliography are new. The concept and the text of the systematic part are that of Poplin; new genera (after 2006) and additional families have been added and updates and edits made throughout. Eric J. Hilton and Lance Grande are responsible for the part on Chondrostei (including Birgeriidae and Saurichthyidae ).

Volumes have been reprinted (vol. 3B) or new editions (vol. 3E replacing vol. 3B and vol. 5 replacing vol. 5) published whereas other volumes have not been published yet. Volume 1C, 3C and 8B are in progress. I hope that additional volumes will follow and be published by the present publisher, Dr. Friedrich Pfeil.

Lawrence, July 2021, H.-P. Schultze