ScienceDaily: Earth & Climate News

Birds and mammals are on extreme ends of the airflow spectrum. Mammals inhale oxygen-rich air and they exhale depleted air, exhibiting a so-called tidal flow pattern. In contrast, bird breath travels tidally through part of the respiratory system, but in a one-way loop throughout most of the lung. Biologists have discovered that Savannah monitor lizards have lung structures that are hybrid system of bird and mammal lungs.

Born pink, blind, and helpless, giant pandas typically weigh about 100 grams at birth -- the equivalent of a stick of butter. Their mothers are 900 times more massive than that. That raises a question that has vexed biologists: why the disparity? No one knows the answer, but by comparing bone growth across newborn bears, dogs and other animals, scientists find that one idea doesn't hold up.