Incredibly large, plant-eating dinosaurs with long necks and tails, pillar-like legs, and contrastingly small heads belong to a group called sauropods: the largest land animals to have ever existed. This includes familiar giants like Apatosaurus, Brachiosaurus, and Diplodocus.  Some specimens weighed over 70 tons and stretched more than 100 feet from head to tail! The amazing anatomy of sauropods has captivated paleontologists for generations and spawned numerous theories about how these giants used their substantial necks. Looking at the long-neckers of today provides some answers.

Long necks allowed sauropod dinosaurs to reach high into the canopies of prehistoric forests and access food resources untouched by other dinosaurs, eliminating competition for the loftier varieties of greenery. Similarly, giraffes browse leaves, fruits, and flowers from tall trees, especially during dry seasons when lower vegetation is scarce, and effectively reduce food competition with other animals. Their long necks, combined with their nearly 18-inch-long tongues, allow them to enjoy a wide range of the savanna’s salad bar.

Sauropod dinosaur necks were marvels of anatomy – one of nature’s most impressive feats of engineering. Unlike mammals, who typically have seven cervical vertebrae regardless of neck length, sauropods evolved additional vertebrae specifically to elongate their necks – some species boasted up to 19 neck vertebrae! These bones were remarkably lightweight due to having hollow chambers that reduced their weight by up to 60% while maintaining structural integrity. The neck was supported by an elaborate system of muscles, tendons, and ligaments, including elastic ligaments that may have helped counteract the enormous gravitational forces acting on the extended neck. Remarkably, despite its exceptionally long neck, a giraffe has the same number of vertebrae in its neck as humans and other mammals – seven cervical vertebrae. However, each vertebra can measure nearly ten inches long!

One of the most intriguing puzzles about long-necked dinosaurs is how their blood was able to circulate all the way to their high-rise heads. Giraffes face similar challenges with their lengthy necks and rely on specialized cardiovascular adaptations to pump blood against gravity. They have large, powerful hearts and complex blood pressure regulation systems that maintain blood flow to the brain and prevent excessive pressure when lowering their heads. Sauropods had necks that were many times longer and must have presented an even greater circulatory challenge. Researchers have calculated that their blood pressure must have been nearly seven times that of humans to supply adequate blood to a head-upright sauropod’s brain. Hypotheses include a series of one-way valves in the neck arteries, multiple auxiliary hearts along the neck, or possibly a completely different circulatory arrangement than modern animals. Some paleontologists suggest that sauropods may have rarely raised their heads to full height because of these circulatory limitations.