Sauropoda ( or ), or the
sauropods (; + , "lizard-footed"), are an
infraorder of
saurischian ("lizard-hipped")
dinosaurs. They had very long necks, long tails, small heads (relative to the rest of their body), and four thick, pillar-like legs. They are notable for the enormous sizes attained by some species, and the group includes the largest animals to have ever lived on land. Well-known
genera include
Brachiosaurus,
Diplodocus,
Apatosaurus and
Brontosaurus.