Open Paleo

Choconsaurus

Simón et al., 2018

Named after Villa El Chocón, the locality in Neuquén Province, Argentina where the holotype was found, + Greek sauros ('lizard'), meaning 'El Chocón lizard'.

100.5–93.9 million years ago Cenomanian, Late Cretaceous
Late Cretaceous stages

Choconsaurus is an extinct genus of herbivorous sauropod dinosaur belonging to the group Titanosauriformes, which lived in the area of present-day Argentina at the end of the Cretaceous.

Under dispute

Placed at Somphospondyli incertae sedis. The describing analysis (Simón and colleagues, 2018) recovered Choconsaurus as a non-eutitanosaurian (basal) titanosaur in its most parsimonious trees, but reported that titanosaur membership is very weakly supported — a position outside Titanosauria (as a non-titanosaurian somphospondylan) is only one step less parsimonious. Somphospondyli is the least-inclusive clade both positions accept.

Diagnosis

  1. Small notch on the dorsal margin of the posterior articular surface of the cervical centra
  2. Dorsal neural spine with subparallel lateral margins in anterior and posterior views
  3. Dorsal vertebrae with a rough and wide prespinal lamina extending for nearly the entire length of the neural spine
  4. Mid- and posterior dorsal vertebrae with accessory laminae placed between the posterior centrodiapophyseal lamina and the accessory posterior centrodiapophyseal lamina
  5. Anterior caudal vertebrae bearing a hyposphene
  6. Scapular blade with rounded expansion on acromial side and acromial process nearly at the midpoint of the scapular body

Species

Choconsaurus baileywillisi Simón et al., 2018

Type species

Named for American geologist Bailey Willis, who traced the stratigraphy of the Neuquén region of Argentina between 1910 and 1914.

Holotype
MMCH-Pv 44/10 , Museo Municipal ‘Ernesto Bachman’, Villa El Chocón
Material
Nearly complete dorsal vertebral series (vertebrae 1-4 and 6-10 or 11), right scapular girdle (scapula, coracoid, sternal plate), and right metacarpus
Horizon
lower Huincul Formation, Cenomanian, Late Cretaceous , 100.5–93.9 million years ago
Locality
La Antena, Neuquén, Argentina

References

  1. Simón, E.; Salgado, L.; Calvo, J. O. (2018). A New Titanosaur Sauropod from the Upper Cretaceous of Patagonia, Neuquén Province, Argentina. Ameghiniana 55(1): 1-29. Asociacion Paleontologica Argentina. doi:10.5710/amgh.01.08.2017.3051

    Describing analysis; recovered Choconsaurus as a basal titanosaur but found that placement very weakly supported, with a non-titanosaurian somphospondylan position only one step longer.

    simón2018a
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Sauropods. Princeton University Press.

    Source of the body length, mass, and hip height estimates.

    jones2026b