Open Paleo

Chakisaurus

Nogueira et al., 2024 SHAH-kee-SOR-us

From Mapudungun chaki ('elder guanaco') + Greek sauros ('lizard'), meaning 'elder guanaco lizard'.

100.5–89.8 million years ago Cenomanian–Turonian, Late Cretaceous
Late Cretaceous stages

Chakisaurus is an extinct genus of elasmarian ornithopod dinosaur from the Late Cretaceous Huincul Formation of Argentina. The genus contains a single species, C. nekul, known from multiple partial skeletons belonging to individuals of different ages. Chakisaurus represents the first ornithischian species to be named from the Huincul Formation.

Diagnosis

  1. Anterior proximal caudal vertebrae with parallelogram-shaped centra in lateral view
  2. Anterior caudals of the distal tail with rod-like, posterodorsally oriented transverse processes
  3. Proximal end of the fibula with a deep, proximodistally extended fossa (possible autapomorphy, unknown in other elasmarians)
  4. Transversely compressed calcaneus, its transverse width about one-third of its anteroposterior length (proportionally narrower than in other elasmarians)
  5. Nearly flat tibial articular surface of the calcaneus
  6. Posterior dorsal vertebrae with a hyposphene articulation bearing a deeply excavated lateral surface

Species

Chakisaurus nekul Nogueira et al., 2024

Type species

From Mapudungun 'nekul' meaning 'swift', in reference to the cursorial habits inferred for this ornithopod.

Holotype
MPCA-PV 816 , Museo provincial de Cipolletti "Carlos Ameghino"
Material
Incomplete postcranial skeleton: posterior dorsal neural arch and centrum, a partial sacrum, several caudal vertebrae, partial left femur, right tibia and left fibula, calcaneus, and pedal phalanges.
Horizon
Huincul Formation, Cenomanian–Turonian, Late Cretaceous , 100.5–89.8 million years ago
Locality
Pueblo Blanco Natural Reserve, Río Negro, Argentina

References

  1. Nogueira, R. A.; Rozadilla, S.; Agnolín, F. L.; García Marsà, J. A.; Motta, M. J.; Novas, F. E. (2024). A new ornithopod from the Upper Cretaceous (Huincul Formation) of northwestern Patagonia, Argentina: Implications on elasmarian postcranial anatomy. Cretaceous Research 159. Elsevier BV. doi:10.1016/j.cretres.2024.105874 nogueira2024a
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.

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

    jones2026a