Abditosaurus (meaning "forgotten lizard") is an extinct genus of titanosaurian sauropod dinosaur from the Late Cretaceous (Maastrichtian) Tremp Group of Catalonia, Spain.

[1] While prospecting for fossil mammals in 1954, German paleontologist Walter Georg Kühne on 25 September discovered the remains of a large titanosaur at the Orcau-1 locality of the Conques Formation of Catalonia, Spain.

During the initial two weeks of excavation Kühne managed to identify around ten bones, some of which were packaged and sent to the Instituto Lucas Mallada (ILM) in Madrid, while others remained at the site (jacketed for protection).

This expedition recovered elements left at the site by the 1955 and 1986 digs, with additional material of the limbs, tooth fragments, ribs and an articulated series of dorsal and cervical vertebrae.

The type specimen, which has numerous accession numbers, is the most complete known European titanosaur skeleton, with the semi-articulated neck, preserving twelve of the estimated fourteen cervical vertebrae, being especially noteworthy.

[6] In 2022, the type species Abditosaurus kuehnei was named and described by Bernat Vila, Albert Sellés, Miguel Moreno-Azanza, Novella L. Razzolini, Alejandro Gil-Delgado, José Ignacio Canudo and Àngel Galobart.

[1] Futalognkosaurus Rukwatitan Epachthosaurus Mendozasaurus Notocolossus Atsinganosaurus Mansourasaurus Paludititan Ampelosaurus Lirainosaurus Opisthocoelicaudia Lohuecotitan Pellegrinisaurus Dreadnoughtus Baurutitan Alamosaurus Neuquensaurus Saltasaurus Maxakalisaurus Paralititan Abditosaurus Patagotitan Maxakalisaurus Paralititan Baurutitan Dreadnoughtus Alamosaurus Abditosaurus Pellegrinisaurus Mendozasaurus Rukwatitan Argentinosaurus Futalognkosaurus Notocolossus Atsinganosaurus Epachthosaurus Saltasaurus Neuquensaurus Nemegtosaurus Opisthocoelicaudia Mansourasaurus Paludititan Ampelosaurus Igai Lirainosaurus Lohuecotitan The discoverers of Abditosaurus interpreted it as a member of Saltasaurinae, a clade of titanosaurs found in South America and Africa.

[1] A subsequent study, using a revised version of the dataset used by Vila and colleagues, found Abditosaurus to occupy a different (non-saltasaurid) position, forming a clade with Alamosaurus, Pellegrinisaurus, Baurutitan, and Dreadnoughtus that was closely related to lognkosaurs.