Sustained miniaturization and anatomical innovation in the dinosaurian ancestors of birds

Abstract

Turning large dinosaurs into small birds Most paleontologists agree that birds are descended from dinosaurs. How did such large terrestrial or aquatic animals evolve into small feathered fliers? Lee et al. used two large databases of theropod morphology to explore possible evolutionary patterns that may have driven this dramatic transformation (see the Perspective by Benton). They found no clear pattern of miniaturization across the entire clade of Theropoda. However, several lines of evidence suggested that the lineage leading to birds underwent sustained miniaturization. Within that lineage, body sizes decreased and species evolved faster. They also developed ecological and morphological innovations linked to smaller body sizes. Science , this issue p. 562 ; see also p. 508