Open Paleo

Eopinacosaurus

Penkalski, 2026 EE-o-pi-NAK-o-SAWR-us

From Greek 'eos' meaning 'dawn' plus Pinacosaurus, referring to the apparent lower stratigraphic or systematic position of the species relative to Pinacosaurus grangeri.

83.6–72.2 million years ago Campanian, Late Cretaceous
Late Cretaceous stages

Eopinacosaurus is an extinct genus of ankylosaurid armored dinosaur known from the Late Cretaceous (Campanian) Bayan Mandahu Formation of Inner Mongolia, China, with a referred skull from the coeval Djadokhta Formation of Mongolia. The genus contains a single species, Eopinacosaurus mephistocephalus, originally assigned to the coeval genus Pinacosaurus.

Diagnosis

  1. Supranarial embayment absent.
  2. Lacrimal incisure absent or rudimentary.
  3. Nasoprefrontal pyramid absent.
  4. Knife-shaped, caudolaterally directed squamosal horns.
  5. Medial segments of first cervical half-ring (h.r.1) broadly oval, with scythe-shaped medial osteoderms.
  6. Straight dorsal border of scapula; no sulcus between anterior and posterior supraorbitals.

Species

Eopinacosaurus mephistocephalus (Godefroit et al., 1999)

Type species

First named as Pinacosaurus mephistocephalus

Honors Mephistopheles (the devil of Faust) plus Greek 'kephalē' meaning 'head', referencing the distinctive squamosal horns.

Holotype
IMM 96BM3/1 , Inner Mongolia Museum, Hohhot
Material
Articulated subadult skeleton with skull, both cervical half-rings, and a nearly complete postcranium in situ; some limb elements and dorsal armor are missing.
Horizon
lower Bayan Mandahu Formation, Campanian, Late Cretaceous , 83.6–72.2 million years ago
Locality
Quarry SBDE 96BM3, Inner Mongolia, China

Synonyms

  • Pinacosaurus mephistocephalus reassigned

    Originally described as Pinacosaurus mephistocephalus by Godefroit and colleagues (1999); Penkalski (2026) transferred the species to the new genus Eopinacosaurus after a specimen-level phylogenetic analysis recovered the holotype outside Pinacosaurus sensu stricto.

References

  1. Penkalski, P. (2026). The morphology and systematics of Pinacosaurus. Historical Biology 1-42. doi:10.1080/08912963.2026.2633178

    Erects Eopinacosaurus to receive 'Pinacosaurus' mephistocephalus Godefroit and colleagues 1999 and recognizes Pinacosaurus hilwitnorum sp. nov. as a second species of Pinacosaurus sensu stricto.

    penkalski2026a
  2. Godefroit, P.; Pereda-Suberbiola, X.; Li, H.; Dong, Z. M. (1999). A new species of the ankylosaurid dinosaur Pinacosaurus from the Late Cretaceous of Inner Mongolia (P.R. China). Bulletin de l'Institut Royal des Sciences Naturelles de Belgique, Sciences de la Terre 69(supp. B): 17-36.

    Original description of Pinacosaurus mephistocephalus (IMM 96BM3/1) from the Bayan Mandahu Formation, recombined as Eopinacosaurus mephistocephalus by Penkalski (2026).

    godefroit1999a