Exploring cranial development in the mourning gecko ( Lepidodactylus lugubris ) through 3D modelling of the chondrocranium

The chondrocranium plays a central role in cranial development. However, its structure and ontogenetic transformations are poorly documented in many reptile lineages, particularly geckos. Here, we present the first detailed 3D reconstruction and anatomical description of the chondrocranium of Lepidodactylus lugubris (Duméril & Bibron, 1836), the mourning gecko, based on PTA-enhanced micro-CT scans of three embryonic stages. We described the neurocranium and splanchnocranium, compared morphology across other gecko species, and mapped selected characters onto a simplified phylogeny. Our findings reveal conserved traits (e.g., a single fenestra optica, an unfenestrated interorbital septum) and unique features (e.g., planum antorbitale contacting the nasal septum, no contact between the auditory capsule and the processus ascendens, and an oval-triangular hypophysial fenestra), the latter recovered as putative autapomorphies of L. lugubris. Several characters showed high variability and possible phylogenetic signal, while others (taenia marginalis, pilae antotica and accesoria, and basicranial fenestra) were ontogenetically variable, highlighting the importance of developmental timing in anatomical interpretations. This study offers a new framework for understanding skull development in geckos, while highlighting the phylogenetic potential of chondrocranial data in reptiles. Besides, it represents the first application of PTA-enhanced micro-CT to visualize embryonic cranial cartilage in reptiles.