Parental care: The key to understanding endothermy and other convergent features in birds and mammals

Birds and mammals share a number of features that are remarkably similar bu t that have evolved independently. One of these characters, endothermy has been suggested to have played a cardinal role in avian and mammalian evolut ion. I hypothesize that it is parental care, rather than endothermy, that i s the key to understanding the amazing convergence between mammals and bird s. Endothermy may have arisen as a consequence of selection for parental ca re because endothermy enables a parent to control incubation temperature. T he remarkable ability of many birds and mammals to sustain vigorous exercis e may also have arisen as a consequence of selection for parental care beca use provisioning of offspring often requires sustained vigorous exercise. B ecause extensive parental care encompasses a wide range of behaviors, morph ology, and physiology it may be a key innovation that accounts for the majo rity of convergent avian and mammalian characters.