Feather biomechanics

Transformations associated with a return to a primarily aquatic ecology have been intensely studied in organisms ranging from insects to cetaceans. However, comparatively little attention has been paid to similar transitions in birds. Co-option of the aerial flight stroke for underwater propulsion has evolved multiple times in diverse lineages within crown clade Aves and has been associated with extremes of body size, growth rate, skeletal modification, and integumentary specialization. While the transition from aerial to aquatic “flight” (wing-propelled diving) has been recognized to involve a profound reorganization of the musculoskeletal system, bone microstructure, and integument, proposed patterns of character acquisition have remained largely hypothetical.

This project, in collaboration with Dr. Julia Clarke (University of Texas at Austin) and Dr. Daniel Ksepka (Bruce Museum; March of the Fossil Penguins blog), encompasses phylogenetic, histologic, functional, and sensory evolution. Work in the lab addresses two major questions.

How does feather structure change with the loss of aerial flight?

In water, feathers must produce forces in a medium that is more than 800 times denser than air. We are study both the microstructure of feathers and their bending properties under loads. We have evidence for the first known fossilized penguin feathers, which will provide valuable comparative data on the early evolution of these unusual structures.

Tarrin Casey (MU School of Medicine Summer Research Fellow from Xavier University, New Orleans) adjusts the apparatus that we use to load feathers in three-point bending.
Our lab-built apparatus for loading feather rachises in cantilever bending. Instron doesn't make off-the-shelve fixtures for our needs, so we have to build them outselves.