Images and measurements of Fezouata marrellid early developmental stages

For the publication: Laibl L, Gueriau P, Saleh F, Pérez-Peris F, Lustri L, Drage HB, Bath Enright OG, Potin GJ-M and Daley AC (2023) Early developmental stages of a Lower Ordovician marrellid from Morocco suggest simple ontogenetic niche differentiation in early euarthropods. Front. Ecol. Evol. 11:1232612. doi: 10.3389/fevo.2023.1232612 High resolution image files, photographs of specimens showing the early developmental stages of the Fezouata Shale marvelled. Photos taken by Lukas Laibl. Specimens were mechanically prepared with a Micro-Jack 4 pneumatic air scribe equipped with a pointed stylus. Photographs were taken using a digital camera Canon EOS 800D coupled with a Canon MP-E 65-mm 1:2.8 1-5X macro lens. A polarizing filter was attached to the lens and the light source to reduce reflections and enhance the contrast between the rock and the specimen. To further increase the contrast, all specimens were immersed in diluted ethanol. The immature specimens were measured using the optical image analyzer TpsDig2 2.31. Eight dimensions of the immature specimens were measured, namely the maximal length and width of the cephalic shield (both including and excluding the cephalic spines), the lengths of the anterolateral, mediolateral, and posterolateral cephalic spines, and the observed length of the trunk. Three folders of images are provided: Raw image files with scale bars that were used for making the measurements (raw_images_measurements); Raw image files of the photographs used in the plates (raw_images_plates); Image files cropped and adjusted for the size in the plates with contrast/brightness adjustments (upgraded_images_plates). In addition, an excel spreadsheets contains the raw data of the measurements.