How did giant dinosaurs with super‑long necks bend down to drink water and then raise their heads without getting really dizzy? While there's no way of being certain, scientists have been studying how tall animals today raise and lower their heads without getting dizzy, such as the giraffe.
Giraffes have really large, powerful hearts that pump blood to the head at high pressure. Giraffes also have soft tissue in their legs that help keep blood from pooling there.
They also have special valves in their arteries that direct blood to the brain and keep it from flowing back down. And, finally, giraffes have a bunch of blood vessels at the base of the brain that regulate blood pressure. When they bend down to drink and rise back up, the vessels slow blood flow to and from the brain to avoid a sudden drop in blood pressure.
There are many examples in nature of different species evolving similar strategies to solve problems. So maybe giraffes work similarly to how giant dinosaurs did long ago.
How Did Long-Necked Dinosaurs Drink Without Getting Dizzy? (National Geographic)