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.
Dallasaurus
Dallasaurus ("Dallas lizard") is a basal mosasauroid from the Upper Cretaceous of North America. Along with "Russellosaurus", "Dallasaurus" is one of the two oldest mosasauroid taxa currently known from North America. This small semi-aquatic lizard measured less than a meter in length, compared to such gigantic derived mosasaurs as "Tylosaurus" and "Mosasaurus", each exceeding 14 meters.