Reptiles had overcome evolutionary hurdles of support and reproduction that limited amphibians. Reptiles had strong ossified skeletons supported by advanced muscular systems for body support and locomotion. Some of largest animals ever to live were dinosaurs of Jurassic Period. Reptiles were also capable of laying amniotic eggs, which kept developing young moist and nourished during gestation. This allowed for first fully terrestrial animal life cycles. Dinosaurs may have been dominant land animals, but y were not alone. Early mammals were mostly very small herbivores or insectivores and were not in competition with larger reptiles. Adelobasileus, a shrew-like animal, had differentiated ear and jaw bones of a mammal and dates from late Triassic. Thus, option B is correct and or options are wrong.