Final answer:
The claim that the oldest dinosaurs date to the Late Jurassic about 225 million years ago is false; dinosaurs first appeared in the late Triassic, around 230 million years ago.
Step-by-step explanation:
The statement that the oldest dinosaurs are of the Late Jurassic age, about 225 million years old, is false. Dinosaurs first appeared much earlier, around 230 million years ago, during the latter part of the Triassic Period. The Jurassic Period followed the Triassic and spanned from 201 to 145 million years ago, which is not when the oldest dinosaurs appeared.
The Mesozoic Era, which is known as the Age of Reptiles, includes three periods: Triassic, Jurassic, and Cretaceous. It was during the early part of this era, specifically the late Triassic, that dinosaurs became dominant on Earth. The Cretaceous Period saw the peak of dinosaur evolution and distribution before their eventual extinction about 65 million years ago at the Cretaceous-Paleogene boundary.