What is the evidence that dinosaurs were endotherms? What is the evidence that they were ...

Bones of endotherms typically have numerous passageways that contain blood vessels, but ectotherm
bones contain fewer passageways. Some dinosaur fossils have bones like endotherms, but they are
ectotherms. Endotherms must eat more than ectotherms because they have a higher metabolic rate, so
endothermic predators would require more prey. While it is difficult to tell, dinosaur predators make
up 3 to 5 of the total population, in line with their being predators. Large-brained animals are
endothermic to keep the brain at constant body temperatures. Some dinosaurs had large brains,
especially small- and medium-sized carnivores, but many did not. Theropods in China have been
found with feathers, and today only endotherms have this insulation. It is likely that large sauropods
were ectothemic, but many theropods and some ornithopods were likely endothermic.

Saurischian dinosaurs have a lizard-like pelvis, and Ornithischian dinosaurs have a bird-like pelvis.
These dinosaurs had a common ancestor, much like archosaurs. Archosaurs were small, long-legged
carnivores that walked and ran on their hind limbs, meaning that they were bipedal.

Plants had to solve some of the same problems that animals did by dealing with the effects of
desiccation, gravity, and reproduction. Vascular plants have a tissue system for the movement of water
and nutrients, and for support. The development of seeds allowed plants to reproduce without
problems of drying out.

Amphibians were limited in colonizing land because they had to return to water to lay their gelatinous
eggs. Reptiles developed amniote eggs in which the developing embryo is surrounded by a liquidfilled
sac and provided with food and a waste sac. This egg allowed reptiles to colonize all parts of the
land.