Fish otoliths from the Paleocene of Bavaria

Otoliths of 54 teleost species are reported from the Paleocene strata of Kressenberg in Bavaria and Kroisbach in Austria, representing 31 families: 33 new species are described, 7 remain in open nomenclature.

Until only 25 years ago, descriptions of Paleocene otolith assemblages were very scarce. The increase in knowledge since then has resulted in more than 100 valid otolith based species, with the fauna described here ranking as the largest and most diverse. While Kressenberg represents mainly a neritic shelf fauna, the Kroisbach association includes a number of truly open marine faunal elements, mostly Stomiiformes, and is the first of its kind from the Paleocene.

The various Paleocene otolith based fish faunas show a remarkable degree of regional diversification. The data accumulated during the past 25 years from the U.S.A., Belgium, Denmark, Greenland and the Ukraine allow for a first paleobiogeographic evaluation of the Paleocene fish fauna as reconstructed from otoliths.

This Paleocene collection is also remarkable for its transitional nature in the evolution of the Teleostei documenting forms that came after the K-T-boundary extinction event and before the rise of the modern Teleostei in the Eocene after the Paleocene/Eocene Thermal Maximum (PETM) event. Hence, there are only very few Paleocene species in common with either the Late Cretaceous, Maastrichtian, which was recently described from nearby outcrops in Bavaria, or the Eocene. The main difference from the older faunal assemblage of the Maastrichtian is the low level of extinct otolith morphologies in the Paleocene and the abundance of plesiomorphic morphologies, which represent modern groups for example of the Percoidei. Other common groups with plesiomorphic morphologies are the Congridae, the Ophidiiformes and the Stomiiformes (in Kroisbach). They are often difficult to associate with living genera and in some cases even families and give rise to the large percentage of taxa considered as 'extinct plesiomorphic' or 'missing links' in teleost phylogeny. Gadiformes, which play an important role in the Danish Paleocene are poorly represented. One of the most dominant groups of the Late Cretaceous, the Beryciformes, was still common and specious in the Paleocene of Bavaria, but mostly represented by genera or families persisting until Recent. A good proportion of those groups can be considered as 'living fossils' in the Recent. The phylogenetic analyses and interpretation for several higher taxa are presented in a chapter at the end of this study.

1. Introduction 5
2. Geology and Locations 5
3. Systematic Part 9
3.1 Elopiformes 9
3.2 Anguilliformes 11
3.3 Siluriformes 20
3.4 Stomiiformes 20
3.5 Aulopiformes 24
3.6 Myctophiformes 27
3.7 Gadiformes 29
3.8 Ophidiiformes 37
3.9 Lophiiformes 34
3.10 Beryciformes 35
3.11 Zeiformes 44
3.12 Perciformes 45
4. Faunal reconstruction 53
4.1 Comparison of the Kressenberg and the Kroisbach faunal composition 54
4.2 Regional comparison and paleoecological interpretation 55
4.3 Paleobiogeographic interpretation of Paleocene otolith associations 57
4.4 Paleocene otolith biostratigraphy 67
5. Phylogenetic analyses and evolutionary interpretation 69
5.1 The Paleocene fish fauna: Linking the Late Cretaceous with the modern bloom 69
5.1.1 Evolutionary interpretation 69
5.1.2 Influence of the K-T boundary extinction event for teleost evolution (based on otolith analysis) 70
5.1.3 Influence of the PETM event for teleost evolution (based on otolith analysis) 74
5.2 The Beryciformes: The fate of the survivors from the Cretaceous (deferred extinction, evolutionary stasis leading to 'living fossils', adaption to niches) 74
5.3 The Anguilliformes and Aulopiformes early radiations 76
5.4 The rise of the Ophidiiformes (with an excursion to the Gadiformes) 79
5.5 The early radiation of the Perciformes/Percoidei 79
5.6 The Stomiiformes, Myctophiformes, Macrouridae: Early records of a bathyal fauna 81
6. Acknowledgments 83
7. References 84
8. Addendum 87