Patagotitan

Patagotitan is a genus of titanosaurian sauropod dinosaur from the Early Cretaceous (Albian stage) Cerro Barcino Formation in Chubut Province, Patagonia, Argentina. The genus contains a single species known from at least six young adult individuals, Patagotitan mayorum, which was first announced in 2014 and then named in 2017 by José Carballido and colleagues. Originally thought to be the largest known titanosaur and land animal overall, preliminary studies and press releases suggested that Patagotitan had an estimated length of and an estimated weight of . Later research revised the length estimate down to and weight estimates down to approximately , suggesting that Patagotitan was of a similar size to, if not smaller than, its closest relatives Argentinosaurus and Puertasaurus. Still, Patagotitan is one of the best-known titanosaurs, and so its interrelationships with other titanosaurs have been relatively consistent in phylogenetic analyses. This led to its use in a re-definition of the group Colossosauria by Carballido and colleagues in 2022.

Like Argentinosaurus and other members of its clade, Lognkosauria, Patagotitan was a particularly large and robust titanosaur. It can be distinguished from its close relatives by a suite of unique characteristics in its and , and in the forelimb, and and in the hindlimb. Among these was the presence of accessory vertebral articulations known as the between only one pair of vertebrae at the level of the scapular blade, which was likely a weight-bearing adaptation not seen in any other sauropod (where they were either present between all pairs or between none). Several unique features in the limbs were also likely attachment scars for muscles. In life, Patagotitan lived in a forested region on a floodplain that was dominated by coniferous trees.