Patagotitan

Patagotitan mayorum is a exceptionally well-preserved giant titanosaur. Its description is based on at least six young adult individuals, which together represent about 70% of the skeleton. When first announced, estimates suggested it was the largest dinosaur ever found, reaching 37 m in length and weighing nearly 70 tonnes. However, later studies by Otero et al. (2020) and Paul (2019) revised these figures down to approximately 31 m and 50–60 tonnes. These new estimates place Patagotitan in the same size category as its relatives Argentinosaurus and Puertasaurus.

The animal's anatomy is typical of the Lognkosauria, a group of broad-bodied titanosaurs with widely spaced, columnar limbs and a sturdy torso. Its vertebrae featured large pneumatic chambers, and its neck was likely between 12 and 15 m long. Unlike diplodocids, it had a relatively short tail. The holotype's completeness, which includes full femora and pelvic elements, has allowed scientists to produce more accurate body-mass estimates than are possible for many other giants.

The American Museum of Natural History in New York features a famous full-skeleton mount of the genus. This reconstruction is so long that its head must extend into a corridor to fit within the display gallery.

Patagotitan inhabited the lush floodplains of mid-Cretaceous Patagonia. Its diet consisted of conifers, ferns, cycads, and early flowering plants. The discovery of six individuals at the same site suggests that these dinosaurs lived in groups. Bone histology shows they followed a fast-growth strategy, reaching sexual maturity at around 30 years of age and continuing to grow after that. An adult's massive size provided protection against all but the largest predators, leaving only the juveniles at risk.

Biomechanical models of its long neck (Sellers et al. 2013) suggest that Patagotitan could feed across a broad horizontal arc while standing still. This ability helped it conserve energy, giving it an advantage over smaller, more active browsers.

• MPEF-PV 3399 — holotype, Museo Paleontológico Egidio Feruglio, Trelew, Argentina; substantial multi-individual material.
• AMNH cast — full-skeleton replica at the American Museum of Natural History, New York; one of the largest mounted dinosaurs in the world.
• Field Museum cast — Field Museum of Natural History, Chicago.

Mass estimate — initial 2017 figures of ~70 tonnes were revised down to ~50–60 tonnes by 2020. Length — initial 37 m revised down to ~31 m. Comparison with Argentinosaurus — Patagotitan and Argentinosaurus are now considered close in size, with the "largest dinosaur" title contested between them and the older fragmentary giants. Phylogenetic position within Lognkosauria — well-supported as close to Argentinosaurus and Puertasaurus.

Patagotitan received major media coverage at its 2014 announcement (when initial size estimates suggested it was the largest dinosaur ever) and at its 2017 formal description. The AMNH mount is one of the museum's flagship exhibits and a popular Instagram subject.

• argentinosaurus
• sauropodomorpha
• brachiosaurus

• Carballido, J. L., et al. (2017). A new giant titanosaur sheds light on body mass evolution among sauropod dinosaurs. Proc. R. Soc. B, 284, 20171219.
• Otero, A., et al. (2020). Forelimb posture in Patagotitan mayorum. Acta Palaeontologica Polonica, 65, 461–479.
• Paul, G. S. (2019). Determining the largest known land animal: a critical comparison of differing methods for restoring the volume and mass of extinct animals. Annals of Carnegie Museum, 85, 335–358.
• Sellers, W. I., et al. (2013). March of the titans: the locomotor capabilities of sauropod dinosaurs. PLOS ONE, 8, e78733.