The heads (and brains) of the long-necked dinosaurs were held high above their hearts. In the larger sauropods, the head could be up to 26 feet (8 m) above the heart! This presents a problem in blood-flow engineering. Paleontologists use giraffes as models to estimate Brachiosaurus blood flow. Brachiosaurus’ neck articulation was more vertical (giraffe-like) than a lot of other sauropods, and could feed at heights of about 30 feet.
In order to pump enough oxygenated blood to the head to operate a Brachiosaurus’ brain (even this tiny sauropod brain) would require:
- A large, powerful heart
- A heart weighing about 880 pounds (400 kg) would be needed to pump blood up the huge blood vessels at high pressure.
- Tremendous blood pressure
- It has been estimated that large sauropods needed a pumping (systolic) blood pressure of over 600 mm of Hg (Mercury). In contrast, most mammals (including people) have systolic pressure of about 100 - 150 mm of Hg. Even the giraffes only have a systolic pressure of about 300 mm of Hg.
- Huge, muscular blood vessels
- Very wide arteries would be necessary to contain neck blood flow. These vessels would need many one-way valves to keep the blood from flowing back down again before reaching the top. Also, when the neck bends downwards, too much back-flow of blood to the head would necessitate one-way valves in the veins.