Halecomorph actinopterygians from the Kimmeridgian of Brunn: insights into the origin and evolutionary dynamics of the fishes from the Solnhofen Archipelago

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The Jurassic was crucial for the evolution of modern vertebrate faunas. Profound geographic and climatic changes occurred to our planet during this period of time, and most of our modern vertebrate groups have their first diversification and radiation. One of the most important areas for our understanding of Jurassic vertebrate diversity and evolution is the Late Jurassic lagerstätte complex of the Solnhofen Archipelago in Southern Germany. This series of exceptional lagerstätten formed around the Kimmeridgian-Tithonian at the northern margin of the Tethyan ocean, in a tropical shallow marine carbonate platform environment. Among this complex, the oldest (Late Kimmeridgian) locality of Brunn has yielded an excellently preserved vertebrate fauna, including selachians, several groups of actinopterygian osteichthyans, and some clades of tetrapods. This fauna is thus of greatest interest for our understanding of the origin and evolutionary dynamics of the vertebrate fauna of the Solnhofen Archipelago. The still unstudied halecomorph actinopterygian fauna of Brunn includes potentially endemic species (caturids) as well as more widely distributed Kimmeridgian taxa, which are absent in the Tithonian (the species Ophiopsis muensteri and Ainia armata). With an almost complete record throughout the Jurassic, these fishes represent a very interesting case for evolutionary studies, including analyses of speciation rates and historical biogeography. The biogeographical analyses of the Brunn halecomorphs further approaches a synthesis of both ecological and historical biogeography since both palaeoecological and historical factors are most probably necessary to explain the diversity of these fishes within the palaeoarchipelago. Therefore, the present project is proposed to analyse the halecomorphs from Brunn in detail and explore the patterns and possible causes of faunal changes in halecomorph fishes within the Solnhofen Archipelago in particular, and in the Late Jurassic of the north-western rim of the Tethys in general.