Propagation phase contrast synchrotron X-ray micro computed tomography of four skull of Lystrosaurus

Four skull of the genus Lystrosaurus have been imaged on the BM18 beamline of the ESRF with the aim of characterising their endocranial cavities. BP/1/3900: Lystrosaurus murrayi (Dicynodontia) LAZ, Karoo Basin, Induan (Early Trias-sic). Voxel size: 0.067 mm (BM18, ES1552). NMQR 3641: Lystrosaurus declivis (Dicynodontia) LAZ, Karoo Basin, Induan (Early Trias-sic). Voxel size: 0.066 mm (BM18, ES1552 ). BP/1/8496: Lystrosaurus maccaigi (Dicynodontia), Lystrosaurus maccaigi-Moschorhinus Subzone of the DAZ, Karoo Basin, Changhsingian (late Permian). Scanned at ESRF. Voxel size: 0.067 mm (BM18, ES1552). BP/1/2241: Lystrosaurus maccaigi (Dicynodontia), Lystrosaurus maccaigi-Moschorhinus Subzone of the DAZ, Karoo Basin, Changhsingian (late Permian). Voxel size: 0.067 mm (BM18, IH-ES-1666). The latter specimen, BP/1/2241, was imaged using a derivative of the attenuation protocol. The specimen was placed inside a 35 cm diameter tube, which was filled with 1–2 mm glass pebbles. The tube was positioned to match the natural horizontal intensity profile of the BM18 beam, which exhibits higher intensity at the center, and was aligned accordingly with the beam axis.
For flat-field correction, two image series were recorded through the tube filled with glass pebbles but without the specimen. During acquisition, the tube was moved in a helical motion along the vertical axis. The median of all recorded images was computed to capture the average attenuation profile of the pebble-filled tube, which was then used as the background signal for the acquisition.