Practice question

Birds originated from small feathered theropod dinosaurs within archosaurian Reptilia evidenced by fossil intermediates like Archaeopteryx lithographica from Late Jurassic Solnhofen limestone preserving reptilian teeth, long bony tail, clawed fingers and avian asymmetric flight feathers, fused furcula, and recent feathered dinosaurs from Liaoning China including Microraptor four-winged glider and Anchiornis. Synapomorphies include pneumatic bones, bipedal stance, brooding behavior, furcula fused clavicles. Molecular phylogeny firmly nests Aves within Dinosauria, not direct descent from fishes amphibians or mammals but reptilian archosaur lineage.