Open Paleo

Jakapil

Riguetti et al., 2022 ja-ka-pill

From 'Ja-Kapïl', a Puelchean word meaning 'shield bearer', in reference to its thyreophoran armor. The species name 'kaniukura' means 'crest stone' in Mapudungun.

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

Jakapil is a genus of basal thyreophoran dinosaur from the Late Cretaceous (Cenomanian-aged) Candeleros Formation of Argentina. The type species is Jakapil kaniukura.

Under dispute

Jakapil is a Late Cretaceous Patagonian thyreophoran. Its describers recovered it as a basal thyreophoran or a stem ankylosaur, closely related to Scelidosaurus, depending on the matrix, and rejected a parankylosaur relationship (Riguetti and colleagues, 2022). Fonseca and colleagues (2024) recover it outside Eurypoda under equal weights and as the earliest ankylosaur under implied weights, while Raven and colleagues (2023) suggested it may be an armored marginocephalian or another non-thyreophoran ornithischian.

Diagnosis

  1. Large ventral crest on posterior lower jaw composed of dentary, angular, and splenial
  2. Dorsomedially directed process on short retroarticular process
  3. Leaf-shaped tooth crowns with prominent mesial edge on labial surface
  4. Maxillary teeth pointed and strongly asymmetrical; dentary teeth slightly curved distally with rounded contour
  5. Elongated and slender postzygapophyses in dorsal vertebrae
  6. Strongly reduced humerus relative to femur with deep proximal fossa
  7. Very large fibula relative to femur
  8. Flattened and thin disk-like postcranial osteoderms

Species

Jakapil kaniukura Riguetti et al., 2022

Type species

From Mapudungun 'kaniukura' meaning 'crest stone', in reference to the uniquely deep jaw of the animal.

Holotype
MPCA-PV 630 , Museo provincial de Cipolletti "Carlos Ameghino"
Material
Partial skeleton of subadult individual preserving cranial fragments (premaxilla, maxilla, basisphenoid), ~15 teeth, nearly complete left lower jaw plus isolated surangular, 12 vertebral elements, dorsal rib and 15 rib fragments, partial coracoid, nearly complete left scapula, partial right scapula, two partial humeri, possible partial ulna, metacarpals, three ischial and two femoral fragments, distal tibia, proximal fibula, pedal phalanges, and 40+ osteoderms.
Horizon
upper Candeleros Formation, Cenomanian, Late Cretaceous , 100.5–93.9 million years ago
Locality
Cerro Policía, Río Negro, Argentina

References

  1. Riguetti, F. J.; Apesteguía, S.; Pereda-Suberbiola, X. (2022). A new Cretaceous thyreophoran from Patagonia supports a South American lineage of armoured dinosaurs. Scientific Reports 12(1). Springer Science and Business Media LLC. doi:10.1038/s41598-022-15535-6

    Named Jakapil and recovered it as a basal thyreophoran or stem ankylosaur, depending on the matrix.

    riguetti2022a
  2. Paul, G. S. (2024). The Princeton Field Guide to Dinosaurs (3rd ed.). Princeton University Press.

    Source of the appearance features.

    paul2024a
  3. Raven, T. J.; Barrett, P. M.; Joyce, C. B.; Maidment, S. C. R. (2023). The phylogenetic relationships and evolutionary history of the armoured dinosaurs (Ornithischia: Thyreophora). Journal of Systematic Palaeontology 21(1): 2205433. doi:10.1080/14772019.2023.2205433

    Suggested Jakapil may be an armored marginocephalian or another non-thyreophoran ornithischian.

    raven2023a
  4. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.

    Treats Jakapil as a basal thyreophoran near Scelidosaurus.

    jones2026a
  5. Fonseca, A. O.; Reid, I. J.; Venner, A.; Duncan, R. J.; Garcia, M. S.; Müller, R. T. (2024). A comprehensive phylogenetic analysis on early ornithischian evolution. Journal of Systematic Palaeontology 22: 2346577. doi:10.1080/14772019.2024.2346577

    Recovered Jakapil outside Eurypoda under equal weights, and as the earliest ankylosaur under implied weights.

    fonseca2024a