Open Paleo

Animantarx

Carpenter et al., 1999 ann-i-MAN-tarks /ænɪˈmæntɑːrks/

From Latin 'animatus' meaning 'living' or 'animated' and 'arx' meaning 'fortress' or 'citadel', meaning 'living citadel', referring to its heavily armored body.

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

Animantarx is a genus of nodosaurid ankylosaurian dinosaur from the Early and Late Cretaceous of western North America. Like other nodosaurs, it would have been a slow-moving quadrupedal herbivore covered in heavy armor scutes, but without a tail club. The skull measures approximately 25 cm (10 inches) in length, suggesting the animal as a whole was no more than 3 meters (10 feet) long.

Diagnosis

  1. Parietal region highly domed
  2. Postorbital horns very small
  3. Deltopectoral crest shoulder very high, near level of humeral head, unlike all other nodosaurids
  4. Coracoid elongated, about 63% of scapula length
  5. Oblique ridge on anterolateral surface of femur below lesser trochanter
  6. Armor pattern of skull roof indistinguishable (individual plates not discernible)

Species

Animantarx ramaljonesi Carpenter et al., 1999

Type species

Named for Ramal Jones, who discovered the holotype following a radiological survey of the area.

Holotype
CEUM 6228R , College of Eastern Utah Prehistoric Museum
Material
Partial skull and right mandible, cervical and dorsal vertebrae, ribs, both scapula-coracoids, fragment of sternal plate, right humerus, left ilium with ischium, left femur
Horizon
Mussentuchit Member, Cedar Mountain Formation, Cenomanian, Late Cretaceous , 100.5–93.9 million years ago
Locality
Carol Site, Utah, United States

References

  1. Carpenter, K.; Kirkland, J. I.; Burge, D.; Bird, J. (1999). Ankylosaurs (Dinosauria: Ornithischia) of the Cedar Mountain Formation, Utah, and their stratigraphic distribution. Vertebrate Paleontology in Utah (Gillette, D. D., ed.) 99-1: 243-251.

    Dates the member by a radiometric age of 98.39 Ma, early Cenomanian on the ICS chart v2024/12, though it reads the fauna as Late Albian or Early Cenomanian.

    carpenter1999a
  2. Paul, G. S. (2024). The Princeton Field Guide to Dinosaurs (3rd ed.). Princeton University Press.

    Source of the mass estimate.

    paul2024a
  3. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.

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

    jones2026a