Failure in a field of success - phylogeny, classification and palaeodiversity of Slit Shells (order Pleurotomariida: Gastropoda)

• Applicant: Professor Dr. Alexander Nützel
• Subject Area: Palaeontology
• Term: from 2018 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 413609851

During the first two years of the project “Failure in a field of success - phylogeny, classification and palaeodiversity of slit shells (order Pleurotomariida: Gastropoda)” we produced three comprehensive taxonomic monographs on Carboniferous, Permian and Triassic Pleurotomariida, in accordance with our research plan for the current project. The taxonomic analyses were very successful and led to numerous clarifications (e.g., new combinations) based on a thorough re-evaluation of morphological characters of type material and well-preserved non-type material. These taxonomic clarifications form an essential prerequisite for phylogenetic and diversity analyses. In these monographs we described 149 species (102 Pleurotomariida, many of them type species of genera), including 31 new species (22 Pleurotomariida) and 11 new pleurotomariidan genera. We documented previously unknown early shell morphology and ontogenetic development of many taxa, improved the descriptive terminology and revised classification of Pleurotomariida on the genus and family level. Additionally, 500 specimens (belonging to more than 400 species) including important type material have been studied and photographed during the collection visits to be used in the phylogenetic analyses. Half of the planned collection visits and data acquisition could not be conducted due to the corona pandemic (especially the planned trip to the US and Sicily had to be cancelled). To a certain degree we were successful to overcome this by intense work on our own collections in Munich, the collections in Vienna, London, and Cortina d'Ampezzo as well as literature analysis. However, the re-design of our original work plan as well as limited access to our research facilities during the lock-downs lead to delays for planned analyses which are well under way but need more time. Phylogenetic analyses and investigation of diversity dynamics were two main goals of the initial project. First result of diversity analysis is to be published soon and phylogenetic analyses are underway (character coding and data matrix). Both need more elaboration and thus an extension of the project duration is desirable. I am therefore applying for an extension of funding for one more year. Within the extended year, the phylogenetic analysis and the diversity analysis will be completed, and the results will be submitted as two separate manuscripts. In the phylogenetic analysis, parsimony analysis and Bayesian inference methods (Fossilized Birth Death Model) will be employed. In the diversity analysis, the diversity change will be investigated with sampling standardization techniques and the environmental affinity hypothesis will be investigated. Preliminary analysis suggests carbonate affinity of Paleozoic gastropod taxa (including Pleurotomariida) and replacement of these groups by taxa with broader environmental affinity during the Mesozoic.

• DFG Programme: Research Grants