Argentinosaurus in the context of "Titanosauria"

Sauropoda (/sɔːˈrɒpədə/), whose members are called sauropods (/ˈsɔːrəpɒdz/; from sauro- + -pod; lit. 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their body), and four thick, pillar-like legs. They are notable for the enormous sizes attained by some species, and the group includes the largest animals to have ever lived on land. Well-known genera include Alamosaurus, Apatosaurus, Argentinosaurus, Brachiosaurus, Brontosaurus, Camarasaurus, Diplodocus, Dreadnoughtus, and Mamenchisaurus.

The oldest known unequivocal sauropod dinosaurs are known from the Early Jurassic. Isanosaurus and Antetonitrus were originally described as Triassic sauropods, but their age, and in the case of Antetonitrus also its sauropod status, were subsequently questioned. Sauropod-like sauropodomorph tracks from the Fleming Fjord Formation (Greenland) might, however, indicate the occurrence of the group in the Late Triassic. By the Late Jurassic (150 million years ago), sauropods had become widespread (especially the diplodocids and brachiosaurids). By the Late Cretaceous, one group of sauropods, the titanosaurs, had replaced all others and had a near-global distribution. However, as with all other non-avian dinosaurs alive at the time, the titanosaurs died out in the Cretaceous–Paleogene extinction event. Fossilised remains of sauropods have been found on every continent, including Antarctica.

Size is an important aspect of dinosaur paleontology, of interest to both the general public and professional scientists. Dinosaurs show some of the most extreme variations in size of any land animal group, ranging from tiny hummingbirds, which can weigh as little as two grams, to the extinct titanosaurs, such as Argentinosaurus and Bruhathkayosaurus which could weigh as much as 50–130 t (55–143 short tons).

The latest evidence suggests that dinosaurs' average size varied through the Triassic, early Jurassic, late Jurassic and Cretaceous periods, and dinosaurs probably only became widespread during the early or mid Jurassic. Predatory theropod dinosaurs, which occupied most terrestrial carnivore niches during the Mesozoic, most often fall into the 100–1,000 kg (220–2,200 lb) category when sorted by estimated weight into categories based on order of magnitude, whereas recent predatory carnivoran mammals peak in the range of 10–100 kg (22–220 lb). The mode of Mesozoic dinosaur body masses is between one and ten metric tonnes. This contrasts sharply with the size of Cenozoic mammals, estimated by the National Museum of Natural History as about 2 to 5 kg (4.4 to 11.0 lb).

Fernbank Museum of Natural History, in Atlanta, Georgia, is a museum that presents exhibitions and programming about natural history. The museum has a number of permanent exhibitions and regularly hosts temporary exhibitions in its expansive facility, designed by Graham Gund Architects. Giants of the Mesozoic, on display in the atrium of Fernbank Museum, features a 123-foot (37 m) long Argentinosaurus, the largest dinosaur ever classified; as well as a Giganotosaurus. The permanent exhibition, A Walk Through Time in Georgia, tells the twofold story of Georgia's natural history and the development of the planet. Fernbank Museum has won several national and international awards for one of its newest permanent exhibitions, Fernbank NatureQuest, an immersive, interactive exhibition for children that was designed and produced by Thinkwell Group. The awards NatureQuest has won include the 2012 Thea Award for Outstanding Achievement for a Museum Exhibit and the 2011 Bronze Award for Best Museum Environment from Event Design. The nearby Fernbank Science Center is a separate organization operated by the DeKalb County Board of Education and is not affiliated with Fernbank Museum of Natural History (Fernbank, Inc.).

Alamosaurus (/ˌæləmoʊˈsɔːrəs/; meaning "Ojo Alamo lizard") is a genus of titanosaurian sauropod dinosaurs containing a single known species, Alamosaurus sanjuanensis, from the Maastrichtian age of the Late Cretaceous period in what is now southwestern North America. It is one of the few known titanosaurs to have inhabited North America after the nearly 30-million-year absence of sauropods from the North American fossil record ("sauropod hiatus") and probably represents an immigrant from South America.

Adults would have measured around 26 metres (85 ft) long, 5 metres (16 ft) tall at the shoulder and weighed up to 30–35 tonnes (33–39 short tons), though some specimens indicate a larger body size. Isolated vertebrae and limb bones suggest that it could have reached sizes comparable to Argentinosaurus and Puertasaurus, which would make it the absolute largest dinosaur known from North America. Its fossils have been recovered from a variety of rock formations spanning the Maastrichtian age. Specimens of a juvenile Alamosaurus sanjuanensis have been recovered from only a few meters below the Cretaceous-Paleogene boundary in Texas, with the Naashoibito Member in New Mexico where the holotype was found in also being constrained to the latest Maastrichtian, making it among the last surviving non-avian dinosaur species.

Titanosaurs (or titanosaurians; members of the group Titanosauria) were a diverse group of sauropod dinosaurs, including genera from every continent. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still thriving at the time of the extinction event at the end of the Cretaceous. This group includes some of the largest land animals known to have ever existed, such as Patagotitan, estimated at 37 m (121 ft) long with a mass of 69 tonnes (76 tons), and the comparably-sized Argentinosaurus and Puertasaurus from the same region.

The group's name alludes to the mythological Titans of ancient Greek mythology, via the type genus (now considered a nomen dubium) Titanosaurus. Together with the brachiosaurids and relatives, titanosaurs make up the larger sauropod clade Titanosauriformes. Titanosaurs have long been a poorly-known group, and the relationships between titanosaur species are still not well-understood.