Which of the following correctly distinguishes between Ornithischians and Saurischians in dinosaur taxonomy?

• A. Ornithischians have a bird-like pelvis, while Saurischians have a lizard-like pelvis.
• B. Both Ornithischians and Saurischians have identical pelvic structures.
• C. Ornithischians include modern birds, while Saurischians do not.
• D. Saurischians are exclusively herbivorous, while Ornithischians are exclusively carnivorous.

Answer: (A)

Verified step by step guidance

1. Step 1: Begin by understanding the taxonomy of dinosaurs. Dinosaurs are divided into two major groups based on the structure of their pelvis: Ornithischians and Saurischians.
2. Step 2: Examine the defining characteristic of Ornithischians. Ornithischians are known for having a bird-like pelvis, where the pubis bone points backward, parallel to the ischium.
3. Step 3: Examine the defining characteristic of Saurischians. Saurischians have a lizard-like pelvis, where the pubis bone points forward, away from the ischium.
4. Step 4: Clarify the distinction between these groups. Ornithischians are herbivorous dinosaurs, while Saurischians include both herbivorous and carnivorous dinosaurs. Modern birds evolved from a subgroup of Saurischians called theropods.
5. Step 5: Evaluate the options provided in the question. Use the information about pelvic structure and evolutionary lineage to identify the correct distinction between Ornithischians and Saurischians.