Open Paleo

Daemonosaurus

Sues et al., 2011 DAY-mo-no-SOR-us

From Greek daemon (δαίμων), 'spirit' or 'demon', + Greek sauros, 'lizard'; means 'demon lizard' or 'spirit lizard', likely referring to its fearsome fang-like teeth

205.7–201.4 million years ago Rhaetian, Late Triassic
Late Triassic stages

Daemonosaurus is an extinct genus of possible theropod dinosaur from the Late Triassic of New Mexico. The only known fossil is a skull and neck fragments from deposits of the latest Triassic Chinle Formation at Ghost Ranch. Daemonosaurus was an unusual dinosaur with a short skull and large, fang-like teeth. It lived alongside early neotheropods such as Coelophysis, which would have been among the most common dinosaurs by the end of the Triassic. However, Daemonosaurus retains several plesiomorphic ("primitive") traits of the snout, and it likely lies outside the clade Neotheropoda. It may be considered a late-surviving basal theropod or non-theropod basal saurischian, possibly allied to other early predatory dinosaurs such as herrerasaurids or Tawa.

Under dispute

Daemonosaurus chauliodus is recovered within Morphoraptora in Herrerasauria by recent analyses (Novas and colleagues, 2021; Srivastava and colleagues, 2026); the describing paper (Sues and colleagues, 2011) instead placed it as a basal theropod, while Nesbitt and Sues (2020) could not confidently place it in any dinosaurian subgroup, recovering only a likely basal saurischian. Saurischia is the least-inclusive clade all these hypotheses accept.

Diagnosis

  1. Prefrontal large, occupying about 50% of the dorsal margin of the orbit
  2. Premaxillary and anterior maxillary teeth much enlarged relative to more posterior maxillary teeth; first two dentary teeth large and procumbent
  3. Dorsoventrally deep jugal with prominent lateral ridge; alveolar margin of dentary downturned at symphysis
  4. Ventral process of lacrimal with slender posterior projection extending along anterodorsal margin of jugal
  5. Third cervical vertebra with deep, rimmed, ovoid pleurocoel at junction of centrum and neural arch on anterolateral surfaces
  6. Long posterior process of premaxilla that almost contacts anterior process of lacrimal; antorbital fenestra nearly same size as external naris

Species

Daemonosaurus chauliodus Sues et al., 2011

Type species

From Ancient Greek 'chauliodous' (χαυλιόδους) meaning 'prominent toothed', referring to the animal's large, procumbent front teeth.

Holotype
CM 76821 , Carnegie Museum of Natural History
Material
Nearly complete but transversely crushed skull with mandible and associated anterior cervical vertebrae and ribs
Horizon
Chinle Formation, Rhaetian, Late Triassic , 205.7–201.4 million years ago
Locality
Coelophysis Quarry, New Mexico, United States

References

  1. Sues, H. D.; Nesbitt, S. J.; Berman, D. S.; Henrici, A. C. (2011). A late-surviving basal theropod dinosaur from the latest Triassic of North America. Proceedings of the Royal Society B: Biological Sciences 278(1723): 3459-3464. The Royal Society. doi:10.1098/rspb.2011.0410

    Prints the holotype's coordinates with an eastern longitude, which is impossible for a New Mexico locality and is read as western.

    sues2011a
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

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

    jones2026c
  3. Srivastava, S.; Nesbitt, S. J. (2026). A new taxon of saurischian dinosaur from the Coelophysis Quarry of New Mexico, USA (Triassic: latest Norian or Rhaetian) highlights herrerasaurian diversity in the latest Triassic. Papers in Palaeontology 12(2). doi:10.1002/spp2.70069

    New saurischian description recovering Daemonosaurus within Morphoraptora/Herrerasauria.

    srivastava2026a
  4. Novas, F. E.; Agnolín, F. L.; Ezcurra, M. D.; Müller, R. T.; Martinelli, A. G.; Langer, M. C. (2021). Review of the fossil record of early dinosaurs from South America, and its phylogenetic implications. Journal of South American Earth Sciences 110: 103341. doi:10.1016/j.jsames.2021.103341

    Recovered Daemonosaurus within Morphoraptora in Herrerasauria in their early dinosaur review

    novas2021a
  5. Nesbitt, S. J.; Sues, H. D. (2020). The osteology of the early-diverging dinosaur Daemonosaurus chauliodus (Archosauria: Dinosauria) from the Coelophysis Quarry (Triassic: Rhaetian) of New Mexico and its relationships to other early dinosaurs. Zoological Journal of the Linnean Society 191: 150-179. doi:10.1093/zoolinnean/zlaa080

    Osteological study that could not confidently place Daemonosaurus in any dinosaurian subgroup, recovering only a likely basal saurischian and rejecting the theropod placement.

    nesbitt2020a