What were the dominant land animals during the Jurassic and Cretaceous periods as suggested by the fossils found

Dinosaurs were the dominant terrestrial vertebrates of the Mesozoic, especially the Jurassic and Cretaceous periods. Other groups of animals were restricted in size and niches; mammals, for example, rarely exceeded the size of a domestic cat, and were generally rodent-sized carnivores of small prey.

Explanation:

the answer is a or when it says crossing over

this transfer is call conjunction