The Buzz on Birds and Bees

Where Do Birds Come From?

Predatory Dinosaurs Breathed Like Birds, Study Suggests, Sarah Graham, Scientific American:  A new analysis suggests that theropod dinosaurs such as T. rex shared another characteristic with their modern day bird descendants: their mode of breathing. Although some scientists have posited that the extinct creatures would have had lungs similar to those of today's crocodiles and other reptiles, the results instead indicate that theropods used a more complex pulmonary system resembling that of living birds.  Birds have a number of extra air sacs in their skeletons that supply their lungs with air and enhance their ability to exchange gases.

PLeon P. A. M. Claessens of Harvard University …[said] "The pulmonary system of meat-eating dinosaurs such as T. rex in fact shares many structural similarities with that of modern birds, which, from an engineering point of view, may possess the most efficient respiratory system of any living vertebrate inhabiting the land or the sky,"  The results, published in today's issue of the journal Nature, indicate that the system that birds use for breathing developed before birds themselves evolved. This respiratory adaptation, the authors note, is consistent with the hypothesis that predatory dinosaurs had elevated metabolic rates.

Busy, busy buzzing bees

Why do bees buzz?, M. O'Malley, Newton, Mass. Scientific American:  Gard Otis, a professor of environmental biology at the University of Guelph in Ontario, Canada, who studies bee behaviour, ecology and evolution, explains.  Bees buzz for two reasons. First, the rapid wingbeats of many species create wind vibrations that people hear as buzzes. The larger the bee, the slower the wingbeat and the lower the pitch of the resulting buzz. … In addition some bees, most commonly bumblebees (genus Bombus), are capable of vibrating their wing muscles and thorax (the middle segment of their body) while visiting flowers. These vibrations shake the pollen off the flower's anthers and onto the bee's body. Some of that pollen then gets deposited on the next flower the bee visits, resulting in pollination. … When bumblebees vibrate flowers to release pollen, the corresponding buzz is quite loud. Honeybees (genus Apis) are incapable of buzz-pollination and are usually quiet when foraging on flowers. … some flowers are adapted to pollination by pollinators capable of "buzz-pollination." Tomatoes, green peppers and blueberries all have tubular anthers with the pollen inside the tube. … bumblebees pollinate these crops much more efficiently than honeybees do.