One of the most popular of all dinosaurs, for a long time Brachiosaurus was thought to be the biggest--but in recent years it has been outclassed by even larger herbivores like Argentinosaurus and Sauroposeidon. (See more facts, figures and news about Brachiosaurus.)
Besides its enormous, elephant-dwarfing girth, the most noticeable feature of Brachiosaurus is its extremely long (about 30 feet for an adult) neck. Most paleontologists think this indicates that Brachiosaurus led a giraffe-like lifestyle, nibbling the tops of tall trees, but there's some disagreement about whether this dinosaur's heart would have been powerful enough to pump blood to that height. (An alternative theory is that Brachiosaurus extended its neck parallel to the ground and used its tail as a counterweight.)
It was once thought that the nostrils of Brachiosaurus were located on top of its head, but now it appears that they punctuated the end of its snout, just like other land creatures. (By the way, paleontologists also once thought that Brachiosaurus lived in the water, and stuck out its head like a snorkel!)
