Mammals during the Mesozoic were generally small and relatively inconspicuous compared to the dominant reptiles
Comparing The Size Of Reptiles And Mammals During Mesozoic.
During the Mesozoic Era, reptiles were dominant, and they exhibited a wide range of sizes and forms.
Dinosaurs, which were a group of reptiles, were the dominant terrestrial vertebrates.
Some dinosaurs were relatively small, like the feathered dinosaurs, while others were massive, such as the long-necked sauropods and the large theropods.
They did exist but were not the dominant group. Mammals started to diversify during this era, but their size and ecological impact were limited compared to reptiles.