Sauroposeidon (Greek for "Poseidon lizard"); pronounced SORE-oh-po-SIDE-on
Woodlands of North America
Middle Cretaceous (110 million years ago)
Size and Weight:
About 100 feet long and 60 tons
Extremely long neck; massive body; small head
All we know about Sauroposeidon comes from a handful of vertebrae (neck bones) unearthed in Oklahoma in 1999. These aren't just your garden-variety vertebrae, though--judging by their massive size and weight, it's clear that Sauroposeidon was one of the largest herbivorous dinosaurs that ever lived, outclassed only by the South American Argentinosaurus and its fellow North American Seismosaurus (which may well have been a species of Diplodocus). A few other titanosaurs, like Bruthathkayosaurus and Futalongkosaurus, may also have outclassed Sauroposeidon, but the fossil evidence attesting to their size is even more incomplete.
Based on the limited evidence available, what set Sauroposeidon apart from other enormous, small-brained sauropods and titanosaurs was its extreme height. Thanks to its unusually long neck, this dinosaur may have towered 60 feet into the sky--high enough to peek into a sixth-floor window, if any office buildings had existed back then! However, it's unclear if Sauroposeidon actually held its neck vertically, as this would have placed enormous demands on its heart; one theory is that it swept its neck and head parallel to the ground, sucking up low-lying vegetation like the hose of a giant vacuum cleaner.
By the way, you may have seen an episode of the Discovery Channel show Clash of the Dinosaurs stating that Sauroposeidon juveniles grew to huge sizes by eating insects and small mammals. This is so far from accepted theory that it seems to have been completely made up; to date, there's absolutely no evidence that sauropods were even partly carnivorous. There is, however, some speculation that prosauropods (the distant Triassic ancestors of the sauropods) may have pursued omnivorous diets; perhaps a Discovery Channel intern got his research mixed up!