Otoliths from dredges in the Gulf of Guinea and off the Azores

The purpose of the present compendium of articles is to establish a frame for research of fossil otoliths primarily from the Neogene period of the tropical Atlantic.

This concept was first born when Orangel Aguilera in 2010 approached me with the aim to jointly review otoliths that he and his peers have collected in Central America over more than two decades. The material soon proved to be too large and too diverse to deal with in a single volume and decision was made to break it down into more manageable portions. Such approach also aids to a more in depth creation of a comprehensive knowledge base which we felt would benefit the quality of the publications.

The rich assemblage of otoliths of the mesopelagic family Myctophidae was singled out as the first group of our investigation. The trigger was clearly their abundance and diversity and the prospect of establishing a nucleus for the biostratigraphic usage of these fossils. The study was expanded to also encompass previously published and unpublished myctophid otolith material from other Neogene localities in Central America from collections housed at LACM (collection Fitch) and NMB (collections Kugler, Rohr and Saunders) in order to provide for a more comprehensive review.

It soon turned out that in order to adequately identify fossil otoliths of the species-rich myctophid genus Diaphus a review of the Recent otoliths of this genus would be required. This was made possible with the support of colleagues from AMS, BPBM, CAS, LACM, MCZ, MNHN, Ohe, SMF, USNM and ZMUC and through advise from P. A. Hulley and J. Paxton.

At about the same time I received from Volker Thiel (Bonn) a large collection of otoliths extracted from bottom dredges from eleven transects in the Gulf of Guinea from about 30 m to over 3000 m water depth. This unique collection of sub-recent otoliths and a second smaller one made available from off the Azores by ZMUC gave new insight into our actuo-paleontological understanding of otolith assemblages.

During a visit at the Senckenberg Museum (SMF) in 2010 another unique collection was made available for review, from the Neogene of tropical West Africa this time. The core of this collection was brought together from early exploration wells in Gabon during the years 1954 to 1956 by Ivan de Klasz, then working as biostratigrapher of the first hour in the country. The material was now recovered in the inheritance of Wilhelm Weiler, who became involved through de Klasz as the then leading otolith specialist.

Now this first compendium of two dealing primarily with Neogene otoliths from Central America and West Africa comprises four articles: