Final answer:
Dinosaurs and birds share characteristics such as hollow bones, nest building, and brooding, reflecting their close evolutionary relationship and the descent of birds from theropod dinosaurs.
Step-by-step explanation:
The characteristics that dinosaurs and birds share include hollow bones, nest building, and brooding. These features indicate a close evolutionary relationship, with birds having descended from maniraptoran theropod dinosaurs. Hollow bones, also known as pneumatic bones, contribute to a lightweight but strong skeleton which is important for flight. Both dinosaurs and birds exhibit nest building, suggesting behavioral parallels as well. Brooding, the process where the parent sits on the eggs to keep them warm, indicates that parental care may have been present in dinosaurs similarly to how it is observed in birds today.
Dinosaurs and birds also share a similar respiratory system, indicative of the evolutionary lineage that connects them. The detailed fossil evidence, including specimens like Archaeopteryx, highlights shared traits between dinosaurs and birds, such as feathers modified for flight—a characteristic unique to birds among modern animals.