长颈蜥脚类恐龙生活在侏罗纪和白垩纪。本世纪早期，蜥脚类恐龙化石第一次被发现时，它的颈部被描述为近乎水平。但近来发现的化石则被重新搭建：它的头远远高出地面，有着天鹅般曲线的颈部几乎与地面垂直。这也引起了人们对这种恐龙的血液循环如何为头部提供血液的争论，... Long-necked sauropod dinosaurs live in the Jurassic and Cretaceous. When the Sauropod dinosaur fossil was first discovered in the early part of the century, its neck was described as near-horizontal. But recently discovered fossils have been rebuilt: its head is far above the ground, and the neck with a swan-like curve is almost perpendicular to the ground. It also raises questions about how the blood circulation of this dinosaur can provide blood to the head, ...