400
What is the Topic Sentence of:
The paleontologists hope these two differences—skeleton size and time periods—will help them learn how the T. rex evolved through natural selection into a fast and ferocious predator. In the case of the evolution of the T. rex, scientists may want to study how, over time, succeeding generations of the dinosaur evolved to be so large, have such strong legs, or have such tiny arms.
The paleontologists hope these two differences—skeleton size and time periods—will help them learn how the T. rex evolved through natural selection into a fast and ferocious predator.