Evolutionary novelties in cranial kinesis promote the diversification of nesting strategies, foraging behavior and diet during the adaptive radiation of ovenbird-woodcreeper family (Furnariidae)

The evolution of different cranial kinesis types in modern birds has likely driven somespectacular adaptive radiations. However, in certain taxonomic groups, the functional role ofnew kinesis types remains unclear. This is the case of furnariids, a family of neotropicalpasserines known for their stunning nest diversity and ecomorphological disparity. Thesebirds exhibit two types of kinesis, each showing different degrees of craniofacial modularityand representing a distinct regime of evolutionary convergence in both beak andneurocranium. Nevertheless, the extrinsic factors shaping the traits associated with kinesisremain unknown. In this study, we assessed correlations between shape, kinesis type, and sixecological variables, alongside the role of kinesis in transitions toward domed nests and openhabitats. We found that nest type and diet shaped the evolution of beak and cranial kinesistraits, while diet, foraging behavior, foraging strata, and primary habitat structure influencedneurocranium evolution. Specifically, the emergence of rhynchokinesis predicts the evolutionof domed nests and the colonization of less forested environments. We discuss the role ofmodularity in the association between shape and ecology, the evolution of functionalnovelties in both kinetic groups, and the hierarchical order of ecomorphological diversityevolution through stages of the adaptive radiation.