Question: why is adaptive radiation so common a pattern in evolution

title: Adaptive radiation
text: The evolution of a novel feature may permit a clade to diversify by making new areas of morphospace accessible . A classic example is the evolution of a fourth cusp in the mammalian tooth . This trait permits a vast increase in the range of foodstuffs which can be fed on . Evolution of this character has thus increased the number of ecological niches available to mammals . The trait arose a number of times in different groups during the Cenozoic , and in each instance was immediately followed by an adaptive radiation . Birds find other ways to provide for each other , i.e. the evolution of flight opened new avenues for evolution to explore , initiating an adaptive radiation . Other examples include placental gestation ( for eutherian mammals ) , or bipedal locomotion ( in hominins ) . 

Answer: answer: The evolution of a novel feature may permit a clade to diversify by making new areas of morphospace accessible . The trait arose a number of times in different groups during the Cenozoic , and in each instance was immediately followed by an adaptive radiation . Birds find other ways to provide for each other , i.e. the evolution of flight opened new avenues for evolution to explore , initiating an adaptive radiation .