Postnatal ontogenetic patterns in Avialae (Dinosauria, Theropoda)

• Applicant: Dr. Christian Foth
• Subject Area: Palaeontology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 562995972

Crown birds (Aves) represent one of the most extraordinary vertebrate groups, with their origin dating back to the Late Cretaceous. As the sole surviving dinosaur lineage following the K-Pg mass extinction, they have achieved remarkable taxonomic, morphological, and ecological diversity. While crown group of birds emerged in the Late Cretaceous, the evolutionary history of birds extends further back to the Late Jurassic, traditionally associated with the iconic Archaeopteryx from Germany. However, our current understanding of early avian evolution is primarily informed by Early Cretaceous fossils from China. Numerous phylogenetic and macroevolutionary studies have been conducted on this clade called Avialae, aiming to unravel the complex evolutionary relationships within early bird lineages. However, the postnatal ontogeny of extant birds but also stem birds is not well understood. However, such knowledge is important for understanding patterns of ontogenetic variation in crown birds and their theropod ancestors as well as the impact of potential heterochronic events on the evolution of theropods leading to birds. The overall objective of this proposal is to collect ontogenetic series of multiple crown birds taking their phylogenetic relationship as well as different ecologies and developmental modes into account. After documenting the ontogenetic patterns of single species, the comparison will be extended onto the interspecific level and known ontogenetic variation in stem line representatives. By comparing ontogenetic and phylogenetic changes within Avialae and more basal Coelurosauria with each other potential heterochronic events in early bird evolution will be explored. The project will focus primarily on the postcranium and aims to address the following questions: • What are the main postnatal ontogenetic patterns in the postcranium of crown birds, and what is the plesiomorphic condition? • What are the main ontogenetic changes in the osteology of with respect to the shift from a precocial to an altricial lifestyle? • Based on these patterns, does the comparison of ontogenetic and phylogenetic data provide any evidence for heterochronic evolution in non-avialan theropods, non-avian avialans and crown birds? • Are ontogenetic and potential heterochronic patterns synchronic or affected by modularity, i.e., do different body regions show similar or different types of heterochronies? The primary methods that will be applied to tackle these questions include intra- and interspecific morphological comparisons of ontogenetic series in extant birds with help of ontograms and network analyses in combination with different phylogenetic and ontogenetic comparative methods, multivariate statistics and principal coordinate analyses.

• DFG Programme: Research Grants
• International Connection: China (Hong Kong), United Kingdom
• Co-Investigator: Professorin Dr. Nadia Belinda Fröbisch
• Cooperation Partners: Professor Daniel Field, Ph.D.; Professor Michael Pittman, Ph.D.; Dr. Olivia Plateau