Which statement best describes the relationship between birds and dinosaurs as presented?

Which statement best describes the relationship between birds and dinosaurs as presented?

• A. Birds are living dinosaurs descended from feathered theropods.
• B. Birds are unrelated to dinosaurs
• C. Birds evolved after dinosaurs disappeared
• D. Birds are mammalian descendants

Answer: (A)

Birds and dinosaurs are connected through direct evolutionary lineage: modern birds are living dinosaurs that descended from feathered theropod ancestors. The fossil record shows theropod dinosaurs with feathers and other bird-like features, and over time those features evolved into the characteristics we associate with birds today—feathers, wings, and the specialized anatomy for flight and respiration. Even though many non-avian dinosaurs went extinct at the end of the Cretaceous, the lineage leading to birds survived and diversified into the many species we see now.

That makes the other statements inconsistent. Birds didn’t evolve after dinosaurs disappeared, since their ancestors were already present while many dinosaurs were still alive. They aren’t unrelated to dinosaurs, and they aren’t mammalian descendants.