Neuquén, Argentina
The Candeleros Formation sits just below the Huincul Formation in the Neuquén Basin sequence and has produced Patagotitan mayorum, described in 2017 as potentially the most massive dinosaur ever discovered. It also preserves Giganotosaurus and a diverse fauna of large sauropods and theropods that lived on the isolated South American continent. The formation is helping paleontologists understand how dinosaur body size reached its extreme limits.
Like the overlying Huincul Formation, the Candeleros was deposited by river systems crossing a broad alluvial plain during an interval of warm, wet climate. Channel sandstones and mudstone floodplain deposits alternate through the section. Bones are often found concentrated in channel deposits, where carcasses accumulated during floods. The Neuquén Basin's long record of sediment accumulation has created a thick stack of fossiliferous rock stretching from the Jurassic to the Late Cretaceous.
The formation was known to contain large dinosaur remains for decades before the major discoveries of the 1990s and 2000s. Patagotitan was excavated by a CONICET-Egidio Feruglio Museum team between 2012 and 2015, after farm worker Aureliano Hernandez spotted a bone protruding from the ground on his property. The specimen — representing a minimum of six individuals — was described in 2017 and immediately attracted global media attention.
Patagotitan's femur (thigh bone) alone is 2.4 metres tall — taller than most adult humans.
It took 40 days to excavate all the Patagotitan bones, which were loaded onto trucks for a 250-km journey to the museum.
A cast of Patagotitan is so large it doesn't fit in a single museum hall — at the American Museum of Natural History its neck and head extend into the lobby.
The Candeleros Formation preserves titanosaur sauropods at the absolute upper limit of vertebrate body size — researchers still debate whether biological constraints prevented them from growing even larger.
2 species in our database · sorted by size