Sauroposeidon
The press release in 1999 immediately garnered international media attention, which led to many (inaccurate) news reports of "the largest dinosaur ever!". While "Sauroposeidon" likely represents the tallest known dinosaur taxon, it does not hold records for either the longest or most massive. "Patagotitan" or "Argentinosaurus" make better candidates for the title "World's Largest Dinosaur" (presuming to ignore, as is conventional, "Amphicoelias"), though incomplete fossil evidence makes exact rankings impossible.
Sauropoda
Neosauropoda is quite plausibly the largest clade of dinosaurs ever to have existed, with a few exceptions. Most exceptions are hypothesized to be caused by island dwarfism, although there is a trend in Titanosauria towards a smaller body size. The titanosaurs, however, have also been some of the largest sauropods ever. Other than titanosaurs, a clade of diplodocoids, a group of giants, called Dicraeosauridae, is diagnosed by a small body size. No sauropods were very small, however, for even "dwarf" sauropods are larger than , a size reached by only about 10% of all mammalian species.