Society of Systematic Biologists

From PLoS Biology:

Prior to human settlement 700 years ago New Zealand had no terrestrial mammalsâ�"apart from three species of batsâ�"instead, approximately 250 avian species dominated the ecosystem. At the top of the food chain was the extinct Haast's eagle, Harpagornis moorei. H. moorei (10â�"15 kg; 2â�"3 m wingspan) was 30%â�"40% heavier than the largest extant eagle (the harpy eagle, Harpia harpyja), and hunted moa up to 15 times its weight. In a dramatic example of morphological plasticity and rapid size increase, we show that the H. moorei was very closely related to one of the world's smallest extant eagles, which is one-tenth its mass. This spectacular evolutionary change illustrates the potential speed of size alteration within lineages of vertebrates, especially in island ecosystems.