Feather Characteristics in Extinct Stem Birds and Extant Species



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Flight requires a coherent surface that generates lift. In birds, surface integrity of a feather depends on the locking mechanism of barbs and barbules that preserves the integrity of the feather surface by resisting mechanical loads that would pull the barbs apart. Of the different types of feathers, primaries are especially important to flight. Recent studies have revealed differences in finer features of primary feathers in different species, such as the angle and density of barbs. These differences we observe may provide an interesting perspective on the evolution of avian flight. A recent study revealed a difference in barb angles on the trailing edge of primary feathers between modern species and stem birds. This raises questions about the nature of feather integrity in basal bird lineages. In this project, I present barb angle and barb density data on extinct stem bird species that were not measured before. I use a comparative phylogenetic approach to survey the differences between these Mesozoic birds and several modern taxa. I also ask whether there are correlations between the observable features of barbs and barbules in different functional and phylogenetic groupings of living birds—a connection that cannot currently be evaluated in fossilized feathers, but which is likely to be an important part of the functional and developmental story of feather evolution.



Feather, Evolution, Stem bird, Barb, Barbule