Patagotitan mayorum

Patagotitan mayorum was a colossal titanosaur from the late Albian of Chubut Province, Argentina. Unlike most contenders for the largest dinosaur, it is represented by multiple individuals that collectively preserve much of the neck, trunk, tail and limb skeleton. This makes its proportions more defensible than those of Argentinosaurus, although no complete individual or skull is known. Current reconstructions commonly fall around 31-37.5 metres and 42.5-71.4 tonnes, with roughly 57 tonnes serving as a cautious central estimate.

Its fossils occur between approximately 101.8 and 101.4 million years ago. Values shown here are approximate and reflect the current curated seed dataset.

Collectively the fossils include nine neck vertebral positions, nine of the probable ten dorsal positions, many tail vertebrae, ribs and chevrons, shoulder and chest bones, forelimb elements, pelvic bones and multiple femora. The neck vertebrae are extremely elongated and internally divided into many small air chambers. Thin but tall bony laminae strengthened the dorsal vertebrae, while an accessory hyposphene-hypantrum joint appears to have been retained only between the third and missing fourth dorsals. Broad anterior tail neural spines, an expanded scapular blade, distinctive humeral muscle scars and a straight distal femoral edge help diagnose the species.

• Extremely elongated, camellate neck vertebrae with internal air chambers
• Nine of an inferred ten dorsal vertebral positions represented
• Tall, thin vertebral laminae and vertically directed dorsal neural spines
• Accessory spinal articulation restricted to the third-fourth dorsal junction
• Distinctive first tail vertebra with flat front and convex rear joint surface
• Very broad neural spines and high transverse processes on the anterior tail
• Expanded scapular blade and diagnostic muscle attachment scars on the humerus
• Massive femora reaching approximately 2.38 metres

Ranch worker Aurelio Hernandez spotted the first giant bone at the Mayo family's La Flecha ranch in Chubut Province, and Oscar Mayo alerted palaeontologists at the Museo Paleontologico Egidio Feruglio. Excavations recovered more than 130 bones from at least six similar-sized individuals in three closely spaced flood deposits. Jose L. Carballido, Diego Pol and seven colleagues formally named Patagotitan mayorum in 2017. Patago refers to Patagonia, titan evokes the powerful beings of Greek mythology, and mayorum honours the Mayo family's hospitality during fieldwork.

Discovery credit: Aurelio Hernandez, Oscar Mayo, Museo Paleontologico Egidio Feruglio field team.

Naming authors: Jose L. Carballido, Diego Pol, Alejandro Otero and 6 coauthors.

The La Flecha quarry lay on a low-energy river floodplain represented by muddy sandstone and sandy mudstone of the Cerro Castano Member. Volcanic ash entered the basin, allowing a tuff beneath the fossil beds to be dated to about 101.62 million years ago. Repeated floods buried the Patagotitan remains without significant transport. The wider Cerro Barcino ecosystem included other sauropods, the large theropod Tyrannotitan, crocodyliforms, turtles and sphenodontians, with conifer and flowering-plant wood recorded in the formation.

All six known individuals were similar-sized young adults that died at the same place during at least three separate flooding events. The describing team interpreted this recurrence as site fidelity and possible social behaviour among giant titanosaurs. It is suggestive rather than proof of a permanent herd: the animals were not one simultaneous group death, and the quarry preserves no trackway showing how they moved together. Histology indicates the sampled individuals were still growing. Feeding mechanics and reproduction are reconstructed from sauropods generally because no Patagotitan skull, nest or egg has been identified.

• More than 130 bones from at least six individuals were recovered from the La Flecha quarry.
• The three fossil layers represent separate floods, not one catastrophic herd death.
• A volcanic-ash date places the quarry at approximately 101.62 million years old.
• The holotype preserves both femora along with much of the neck and trunk skeleton.
• The species name mayorum thanks the Mayo family, owners of La Flecha ranch.
• A 2.38-metre femur is taller than most people, yet the known animals were probably still growing.

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1. 01
   The Paleobiology Database

   Open source
2. 02
   A new giant titanosaur sheds light on body mass evolution among sauropod dinosaurs

   Jose L. Carballido, Diego Pol, Alejandro Otero and 6 coauthors · Proceedings of the Royal Society B 284 · 2017

   Open source
3. 03
   The appendicular osteology of Patagotitan mayorum (Dinosauria, Sauropoda)

   Alejandro Otero, Jose L. Carballido, Agustin Perez Moreno · Journal of Vertebrate Paleontology 40(4) · 2020

   Open source
4. 04
   High-resolution chronostratigraphy of the Cerro Barcino Formation (Patagonia)

   J. Marcelo Krause, Jahandar Ramezani, Aldo M. Umazano and 6 coauthors · Gondwana Research 80 · 2020

   Open source
5. 05
   The accuracy and precision of body mass estimation in non-avian dinosaurs

   Nicolas E. Campione, David C. Evans · Biological Reviews 95(6) · 2020

   Open source
6. 06
   Patagotitan mayorum: publication and scientific significance

   Museo Paleontologico Egidio Feruglio · 2017

   Open source
7. 07
   MEF displays more original fossils of Patagotitan mayorum

   Museo Paleontologico Egidio Feruglio · 2025

   Open source
8. 08
   Maximo the Titanosaur

   Field Museum

   Open source
9. 09
   Patagotitan: Dino Directory

   Natural History Museum, London

   Open source