µCT scans of the lepidosaur skull roof

The study of convergently acquired adaptations allows fundamental insight into life's evolutionary history. Within lepidosaur reptiles – i.e. lizards, tuatara, and snakes – a fully fossorial lifestyle has independently evolved in most major clades. However, despite their consistent use of the skull as a digging tool, cranial modifications common to all these lineages are yet to be found. In particular, bone microanatomy, although highly diagnostic for lifestyle, remains unexplored in the lepidosaur cranium. This constitutes a key gap in our understanding of their complexly interwoven ecology, morphology, and evolution. In the article First Evidence of Convergent Lifestyle Signal in Reptile Skull Roof Microanatomy, we set out to bridge this gap by reconstructing the acquisition of a fossorial lifestyle in 2813 lepidosaurs and assessing the skull roof compactness from digital cross-sections in a representative subset (n = 99). The µCT scans presented here complement this article as supplementary raw data. Using the 3D-volume processing software VG-Studio Max 3.3 (RRID:SCR_017997), linear measurements were taken and 2D-slices exported (10.6084/m9.figshare.13084583). These slices were further processed with ImageJ 1.52i (RRID:SCR_003070) including the plug-in BoneJ 1.4.3 in order to quantify differences in skull roof structure between non-fossorial, semi-fossorial, and fully fossorial taxa. Alongside skull roof compactness, we tested skull roof thickness, bone overlap, the length ratio of frontal and parietal bones (rfp), cranial elongation, and skull diameter for a lifestyle signal and their convergent evolution.