Raw data from microCT tomography of Ausichicrinites zelenskyyi

Fossil comatulids, referred to as feather stars, are mostly known from highly disarticulated specimens. A single isolated element (centrodorsal) has been the basis for taxonomic description of a vast majority of fossil comatulids. Here, we report a nearly complete, and thus extremely rare, comatulid from the Upper Jurassic (Tithonian) of the Blue Nile Basin in central western Ethiopia that provides a unique insight into the morphology of comatulid arms and cirri. It is assigned to Ausichicrinites messingi gen. et sp. nov. and is the first Jurassic comatulid from the African continent. The new taxon shows close resemblance with the modern family Zygometridae, exclusively known from the Holocene of the western Pacific and eastern Indian Oceans.

Methods
The slab with the comatulid crinoid was transported from Ethiopia to the Palaeontological Laboratory of the Faculty of Natural Sciences of the University of Silesia in Katowice, Poland, in September 2021. It was cleaned there and photographed using a Canon Eos 350D digital camera. This specimen was also scanned with the X-ray computed tomography (CT-scanning) using a GE PHOENIX v|tome|s at the Institute of Biomedical Engineering, Faculty of Science and Technology, University of Silesia in Katowice, Poland (see Supplementary movies 1, 2). It was investigated using different settings (voltage: 140 kV, amperage: 90 A, exposure time: 333 ms, projections: 2000, voxel resolution: 5 µm). Raw 2D X-ray data were then processed using phoenix datos|x. The movies were prepared using the following application VGStudio Max 2.0. The next step was to professionally prepare the specimen using a chemical method (it was treated with potassium hydroxide - caustic potassium, KOH) by Frank Siegel, Berlin, Germany, from HAUFWERK.COM (https://www.haufwerk.com/). Finally, the specimen was photographed using a Canon Eos 350D digital camera (Fig. 4A-C).