Author Question: What is the evidence that dinosaurs were endotherms? What is the evidence that they were ... (Read 46 times)

joesmith1212 · **on:** Jul 15, 2018

What is the evidence that dinosaurs were endotherms? What is the evidence that they were
ectotherms? What is the conclusion? What will be an ideal response?

Question 2

What are the differences between Saurischian and Ornithischian dinosaurs, and what was their
common ancestor like? What will be an ideal response?

emilymalinowski12 · **Reply #1 on:** Jul 15, 2018

Answer to Question 1

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.

Answer to Question 2

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.