Open Paleo

Amargasaurus

Salgado & Bonaparte, 1991 ah-MAHR-gah-SAWR-us /əˌmɑːrɡəˈsɔːrəs/

Named for La Amarga arroyo in Argentina, where it was discovered, combined with Greek 'sauros' meaning 'lizard', meaning 'La Amarga lizard'.

125.8–121.4 million years ago Barremian, Early Cretaceous
Early Cretaceous stages

Amargasaurus is a genus of sauropod dinosaur from the Early Cretaceous epoch (129.4-122.46 mya) of what is now Argentina. The only known skeleton was discovered in 1984 and is virtually complete, including a fragmentary skull, making Amargasaurus one of the best-known sauropods of its epoch. Amargasaurus was first described in 1991 and contains a single known species, Amargasaurus cazaui. It was a large animal, but small for a sauropod, reaching 9 to 13 meters (30 to 43 feet) in length. Most distinctively, it sported two parallel rows of tall spines down its neck and back, taller than in any other known sauropod. In life, these spines could have stuck out of the body as solitary structures that supported a keratinous sheath. An alternate hypothesis, now more favored, postulates that they could have formed a scaffold supporting a skin sail. They might have been used for display, combat, or defense.

Diagnosis

  1. Dicraeosaurid with split neural spines extending to penultimate presacral
  2. Taller presacral vertebrae with more accentuated bifurcation than Dicraeosaurus hansemanni
  3. Cervical neural spines substantially longer and subcylindrical in cross section
  4. Fused basal tubera of basioccipital
  5. Basipterygoid processes longer than in D. hansemanni
  6. Parietal and postparietal fenestrae present with smaller postparietal relative to parietal
  7. Robust orbitosphenoids with large olfactory nerve opening

Species

Amargasaurus cazaui Salgado & Bonaparte, 1991

Type species

Named for Luis Cazau, a geologist with the YPF oil company who informed Bonaparte's team about the paleontological significance of the La Amarga Formation, leading to the discovery of the skeleton.

Holotype
MACN-N 15 , Museo Argentino de Ciencias Naturales ‘Bernardino Rivadavia’
Material
Basicranial and temporal skull region, 22 articulated presacral vertebrae, 5 fused sacral vertebrae, 3 anterior-middle caudal vertebrae, ribs, scapulocoracoid, humerus, radius, ulna, ilium, femur, tibia, fibula, astragalus, metatarsals.
Horizon
Puesto Antigual Member, La Amarga Formation, Barremian, Early Cretaceous , 125.8–121.4 million years ago
Locality
2.5 km southeast of the La Amarga Arroyo bridge on National Route 40, Neuquén, Argentina

References

  1. Salgado, L.; Carvalho, I. de S.; Garrido, A. C. (2006). Zapalasaurus bonapartei, un nuevo dinosaurio saurópodo de La Formación La Amarga (Cretácico Inferior), noroeste de Patagonia, Provincia de Neuquén, Argentina. Geobios 39(5): 695-707. Elsevier BV. doi:10.1016/j.geobios.2005.06.001

    Gives "Amargasaurus cazaui (lower Barremian, Puesto Antigual, La Amarga Formation)".

    salgado2006b
  2. Bonaparte, J. F. (1984). I dinosauri dell'Argentina [. Sulle Orme dei Dinosauri 125-143. Erizzo Editrice, Esplorazioni e Ricerche. bonaparte1984a
  3. Salgado, L.; Bonaparte, J. F. (1991). Un nuevo sauropodo Dicraeosauridae, Amargasaurus cazaui gen. et sp. nov., de la Formacion La Amarga, Neocomiano de la Provincia del Neuquén, Argentina [A new dicraeosaurid sauropod, Amargasaurus cazaui gen. et sp. nov., from the La Amarga Formation, Neocomian of Neuquén Province, Argentina]. Ameghiniana 28(3-4): 333-346.

    In Spanish.

    salgado1991a
  4. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Sauropods. Princeton University Press.

    Source of the hip height estimate, and the appearance features.

    jones2026b