Modern birds are the only living dinosaurs, retaining the DNA and blood of their prehistoric ancestors [1].
This evolutionary link transforms the understanding of avian biology and underscores the resilience of specific dinosaur lineages. By studying these connections, researchers can better map the history of life on Earth and the mechanisms of survival during global catastrophes.
Birds evolved from theropods, specifically those similar to the Velociraptor [1], [2]. This lineage has been evolving for roughly 150 million years [3]. While most dinosaur species vanished, these ancestors possessed the traits necessary to endure the Cretaceous-Paleogene extinction event.
The defining moment of this survival occurred 66 million years ago [4]. An asteroid impact caused a mass extinction that wiped out the vast majority of terrestrial life — yet the ancestors of modern birds persisted.
Steve Brusatte, a palaeontologist at the University of Edinburgh, said that birds are descendants of these theropod dinosaurs. Following the asteroid impact, these survivors diversified into a wide array of ecological niches to populate the planet [2], [4].
This evolutionary journey from predatory theropods to the diverse species seen today involves a complex transition of physiology. The retention of dinosaur DNA serves as a biological record of this transition, linking the smallest songbirds to the massive creatures of the Mesozoic era [1], [2].
“Birds are the only living dinosaurs; they retain dinosaur DNA and blood”
The classification of birds as dinosaurs shifts the narrative of the Cretaceous-Paleogene extinction from a total disappearance to a selective survival event. It demonstrates that the 'extinction' of dinosaurs was not absolute, but rather a narrowing of the lineage to a single, highly adaptable group of theropods.
