Evolutionary simplification of the dermatocranium in early tetrapods

• Applicant: Dr. Marylene Danto
• Subject Area: Palaeontology
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 442217617

Throughout Paleozoic and Mesozoic stem- and crown-tetrapods, the skull morphology is remarkably divergent and extreme skull modifications (characterized by a frequent losses of bony elements), are observed among the different groups. The extreme end to this trend is exemplified in modern lissamphibians, in which only 19 out of the original 43 dermal skull elements of their early tetrapod ancestors are retained. The best way to understand this evolutionary reduction of numerous dermal bones is to study the underlying developmental processes in a functional-adaptive context. Skull morphology and its associated development have solely been examined separately in a select few early tetrapod taxa, making it easy to lose sight of the big picture of the repeated evolutionary simplification of the dermal skull. I propose to examine if (1) the loss of skull bones is a consequence of resource or habitat limitations, if (2) body size reduction combined with large cell volume induces a simplified skull morphology, if (3) the simplification of the dermal skull bones results from a delay or truncation of the growth trajectory or if (4) the skull morphology and skull bone reduction is associated with the size of the jaw muscles. I will study the skull morphology of a broad selection of early tetrapods that populate important branches of early tetrapod phylogeny and lissamphibians that are adapted to different lifestyles. A morphological analysis (geometric morphometrics) will be complemented by histological and ontogenetic data. The study will clarify how and specifically why dermal bones are lost repeatedly and if this pattern evolved convergently in the different lineages of early tetrapods.

• DFG Programme: Research Grants