Open Paleo

Paraxenisaurus

Serrano-Brañas et al., 2020 peh-rak-sih-nee-sor-us /pɛərəkˌsɪniːˈsɔːrəs/

From Greek para (near, beside) and xenos (strange) and sauros (lizard); meaning "strange lizard".

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

Paraxenisaurus is an extinct genus of ornithomimosaurian theropod from the Late Cretaceous Cerro del Pueblo Formation of Coahuila in Mexico. The genus contains a single species, P. normalensis, which is known from a few bones of tail, hips, hands, and feet. The specific epithet was given in honor of the Benemérita Normal School of Coahuila, a teacher training institution, where the fossils were reposited. It is a member of the family Deinocheiridae and is the only member of that clade known from Laramidia.

Diagnosis

  1. Strongly curved and laterally compressed manual ungual I with distally placed flexor tubercle divided by deep sulcus
  2. Deeply concave proximal articular surface of manual ungual I, elliptical outline, twice taller than wide
  3. Metacarpal III with expanded proximal articular end similar in width to metacarpal II
  4. Posterior caudal vertebrae with low dorsoventrally prezygapophyses having nearly vertical articulation surfaces anteriorly and ventromedially-facing prezygapophyses posteriorly
  5. Non-arctometatarsalian pes with proximal end of metatarsal III expanded and ovoid outline
  6. Expanded medial condyle of metatarsal II flaring laterally
  7. Distal end of metatarsal III transversely wider than anteroposteriorly with semi-ginglymoid articulation

Species

Paraxenisaurus normalensis Serrano-Brañas et al., 2020

Type species

Named in honor of the Benemérita Normal School (Escuela Normal) of Coahuila, Mexico, the teacher-training institution where the holotype fossils were reposited.

Holotype
BENC 2/2-001 , Benemérita Escuela Normal de Coahuila
Material
Partial postcranial skeleton
Horizon
Cerro del Pueblo Formation, Campanian, Late Cretaceous , 83.6–72.2 million years ago
Locality
BENC 2/2, Coahuila, Mexico

References

  1. Serrano-Brañas, C. I.; Espinosa-Chávez, B.; Maccracken, S. A.; Gutiérrez-Blando, C.; de León-Dávila, C.; Ventura, J. F. (2020). Paraxenisaurus normalensis, a large deinocheirid ornithomimosaur from the Cerro del Pueblo Formation (Upper Cretaceous), Coahuila, Mexico. Journal of South American Earth Sciences 101. Elsevier BV. doi:10.1016/j.jsames.2020.102610 serrano-brañas2020a
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

    Source of the hip height estimate.

    jones2026c