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.
Douglas A. Lawson
When the discovery of the fossils was reported in 1975, "Quetzalcoatlus" was the largest flying creature known to have lived. A fellow researcher challenged Lawson's estimates of the dimensions of the wing architecture of "Quetzalcoatlus". However, Lawson responded by demonstrating that while inconsistent with those of modern-day birds, his estimates were consistent with extrapolations of other pterosaurs, such as "Pterodactylus antiquus". In 2010 the U.S. National Park Service described "Quetzalcoatlus" as the world's second-largest known flying creature.