Dinosaur size
There were larger dinosaurs, but knowledge of them is based entirely on a small number of fragmentary fossils. Most of the largest herbivorous specimens on record were discovered in the 1970s or later, and include the massive titanosaur "Argentinosaurus huinculensis", which is the largest dinosaur known from uncontroversial evidence, estimated to have been and long. Some of the longest sauropods were those with exceptionally long, whip-like tails, such as the "Diplodocus hallorum" (formerly "Seismosaurus") and the 33- to 35-metre-long (108–115 ft) "Supersaurus". The tallest was the "Brachiosaurus".
Choristodera
The neochoristoderan taxa Champsosauridae and Simoedosauridae are found from the Late Cretaceous to the middle Eocene, indicating that the group survived the Cretaceous–Paleogene extinction event. "Champsosaurus" teeth, vertebrae, and other bones are common fossils in Cretaceous deposits such as the Dinosaur Park Formation of Alberta and the Lance Formation of Wyoming. The presence of champsosaurs as far north as the North Slope of Alaska implies warmer temperatures during the Cretaceous. The Paleocene species, "Champsosaurus gigas", is the largest known champsosaur. The most complete skeleton was found at the Wannagan Creek site in North Dakota, but is found throughout North American Paleocene strata in the Dakotas, Wyoming, and Montana. "C. gigas" is unusual among Paleocene reptiles in that it is far larger than known Mesozoic ancestors, at about 3 meters in length (10 ft) versus 1.5 meters (5 ft) for the largest Cretaceous champsosaurs.