Subscribe
Subscribe
MY AMERICAN SCIENTIST
LOG IN! REGISTER!
SEARCH
 
Logo IMG

FEATURE ARTICLE

Flights of Fancy in Avian Evolution

From mousebirds to terror birds, the class Aves has encompassed a remarkable diversity of species over the past 150 million years.

Daniel T. Ksepka

Heyday of the Mousebirds

Click to Enlarge ImageClick to Enlarge ImageMost people have never seen a mousebird. These small, social birds are found creeping through vegetation in their namesake mouse-like manner, sometimes clinging upside down using their dexterous grasping toes. Mousebirds are unknown to most because the six living species only occur in sub-Saharan Africa. We might thus assume mousebirds were always minor players in the story of avian evolution. Not so!

Click to Enlarge ImageFossils show that during the Eocene and Oligocene Click to Enlarge ImageEpochs (56 million to 23 million years ago), mousebirds underwent a fascinating diversification that gave rise to a kaleidoscope of different forms. Among the species that flourished in North America and Europe during that golden age of mousebirds were the sharp-billed Chascacocolius cacicirostris, which specialized in prying open bark or hard fruits, the long-winged Celericolius acriala, which most likely chased down insects, and the parrot-skulled Oligocolius psittacocephalon, known from a skeleton packed with seeds. These forms had all vanished by 25 million years ago, possibly losing out to the wildly successful songbirds. They are only one example of many evolutionary radiations that were followed by diversity collapse.




comments powered by Disqus
 

EMAIL TO A FRIEND :

Of Possible Interest

Feature Article: Why Some Animals Forgo Reproduction in Complex Societies

Letters to the Editors: Rodents of Unusual Size

Letters to the Editors: When Horses Fly

Subscribe to American Scientist