In
a finding that could change the way scientists think about bird evolution,
researchers have found that the shape of bird wings is influenced more by how
closely related species are to one another than by flight style.
The
research challenges scientific beliefs that assume the way a bird species
flies--whether it primarily dives, glides or flaps, for instance--plays the
primary role in the evolution of its wing shape. It also indicates that it may
be more difficult than previously thought to infer flying behaviors of early
birds and the first flying dinosaurs from fossils alone.
Julia
Clarke, an associate professor in the Department of Geological Sciences at The
University of Texas Jackson School of Geosciences, conducted the work with Xia
Wang, a post-doctoral researcher who led the study. Their research was
published in the journal Proceedings of the Royal Society B: Biological
Sciences in October.
Bird
wings, unlike stiff airplane wings, are flexible and change shape during
flight. So, their geometry and wing outline may not tell the whole story of a
particular flight style or environment, Clarke said.
"We've
taken a lot for granted. Birds are not airplanes," Clarke said.
By
comparing geometry across species and clades - groups of organisms that evolved
from a common ancestor - the researchers found that birds that are closely
related evolutionarily have similar wing structures, even if the birds show
very different flight styles. For example, albatrosses, penguins and loons,
despite looking very different from one another, all belong to the clade
Aequornithes and have a wing shape that is very similar.
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