To solve the question of which dinosaur fossil among the options is a theropod, we need to understand the classification of dinosaurs and focus on the characteristics of the options provided. Dinosaurs are generally divided into two major groups based on hip structures: Saurischia and Ornithischia. One of the sub-groups of Saurischia is the Theropoda, which includes predominantly carnivorous dinosaurs.
Let's analyze each of the given options:
Based on the classification and characteristics of each dinosaur, Rajasaurus is the correct answer as it is the only one among the options that belongs to the theropod group.
| Group I | Group II |
| P. Dissepiment | 1. Echinodermata |
| Q. Delthyrium | 2. Trilobita |
| R. Pygidium | 3. Brachiopoda |
| S. Ambulacrum | 4. Anthozoa |