Which of the following are the only extant animals that descended directly from dinosaurs?

• A. Crocodiles
• B. Turtles
• C. Lizards
• D. Birds

Answer: (D)

Verified step by step guidance

1. Understand the evolutionary relationship between dinosaurs and modern animals. Dinosaurs are a group of reptiles that lived millions of years ago, and some of their descendants survived the mass extinction event at the end of the Cretaceous period.
2. Recognize that birds are classified as avian dinosaurs. This classification is based on extensive fossil evidence showing that birds evolved from theropod dinosaurs, a subgroup of the larger dinosaur clade.
3. Examine the anatomical features shared between birds and theropod dinosaurs, such as hollow bones, feathers, and specific skeletal structures like the wishbone (furcula). These features provide strong evidence for their evolutionary connection.
4. Differentiate birds from other reptiles like crocodiles, turtles, and lizards. While these animals share a common ancestor with dinosaurs, they are not direct descendants of dinosaurs. Birds are the only extant animals that directly evolved from dinosaurs.
5. Conclude that birds are the correct answer based on evolutionary biology and fossil evidence, as they are the only living animals that descended directly from dinosaurs.