Birds are exceptionally diverse, with more than 10,000 known species—all of them the descendants of dinosaurs. Modern birds consist of 247 families and 10,731 species, more than any other vertebrate group except fish.
source/image: National Geographic
The latest genetic clues and fossil finds suggest that at least three lineages of modern birds arose during the Cretaceous period and survived the mass extinction.
These discoveries are helping us better understand how birds evolved and how they’re related to each other, from the tiny hummingbird to the towering ostrich.
The origin of birds has historically been a contentious topic within evolutionary biology. However, only a few scientists still debate the dinosaurian origin of birds, suggesting descent from other types of archosaurian reptiles. Within the consensus that supports dinosaurian ancestry, the exact sequence of evolutionary events that gave rise to the early birds within maniraptoran theropods is hotly disputed.