Open Paleo

Byronosaurus

Norell et al., 2000 BIE-ruh-no-SAWR-us

Named in honor of Byron Jaffe, in recognition of the Jaffe family's support for the Mongolian Academy of Sciences-American Museum of Natural History Paleontological Expeditions, combined with Greek 'sauros' meaning 'lizard'.

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

Byronosaurus is a genus of troodontid dinosaur from the Late Cretaceous Period of Mongolia.

Under dispute

Byronosaurus is consistently recovered as a troodontine, but often near the base of the subfamily or just outside the derived Saurornithoides-Zanabazar- Troodon clade (Norell and colleagues, 2009; Tsuihiji and colleagues, 2014; Hartman and colleagues, 2019). It is placed in Troodontinae following these analyses.

Diagnosis

  1. Teeth devoid of serrations on the anterior and posterior carinae (unserrated teeth throughout the tooth row).
  2. Presence of a large interfenestral bar that is not inset medially from the lateral surface of the maxilla.
  3. Presence of a connection between the nasal passage and the antorbital fenestra through the interfenestral bar.
  4. A horizontal groove on the maxilla adjacent and parallel to the tooth row, containing small foramina.

Species

Byronosaurus jaffei Norell et al., 2000

Type species

Named for Byron Jaffe, in recognition of the Jaffe family's support for the Mongolian Academy of Sciences-American Museum of Natural History Paleontological Expeditions.

Holotype
IGM 100/983 , Paleontological Center, Mongolian Academy of Sciences
Material
Fragmentary skull (rostral fragment and braincase preserved separately) and postcranial bones; skull broken at anterior margin of orbits; braincase three-dimensionally preserved with roof missing.
Horizon
Bayn Dzak Member, Djadokhta Formation, Campanian, Late Cretaceous , 83.6–72.2 million years ago
Locality
Ankylosaur Flats, Ukhaa Tolgod, Ömnögovi, Mongolia

Synonyms of the genus

Name Type Reason
Byranjaffia junior subjective Treated as a junior synonym of Byronosaurus; remains a nomen nudum.

Notable specimens

  • IGM 100/972, IGM 100/974

    Paleontological Center, Mongolian Academy of Sciences reproductive

    Two front skulls and lower jaws of perinates (hatchlings or near-hatching embryos), skull lengths about 22.6 and 25.4 cm, found in an oviraptorid (Citipati) egg nest at the Flaming Cliffs. First called Velociraptor, later referred to this genus, but the referral was contested in 2017.

    Bever & Norell (2009)

References

  1. Ding, A.; Pittman, M.; Upchurch, P.; O'Connor, J.; Field, D. J.; Xu, X. (2020). The biogeography of coelurosaurian theropods and its impact on their evolutionary history. Pennaraptoran Theropod Dinosaurs: Past Progress and New Frontiers (Pittman, M.; Xu, X., eds.) 440: 117-157. American Museum of Natural History, New York.

    Gives the holotype locality as "Ankylosaur Flats, Ukhaa Tolgod".

    ding2020a
  2. Norell, M. A.; Makovicky, P. J.; Clark, J. M. (2000). A new troodontid theropod from Ukhaa Tolgod, Mongolia. Journal of Vertebrate Paleontology 20(1): 7-11. Informa UK Limited. doi:10.1671/0272-4634(2000)020[0007:anttfu]2.0.co;2 norell2000a
  3. Bever, G. S.; Norell, M. A. (2009). The perinate skull of Byronosaurus (Troodontidae) with observations on the cranial ontogeny of paravian theropods. American Museum Novitates (3657): 1-51. doi:10.1206/650.1 bever2009a
  4. Paul, G. S. (2024). The Princeton Field Guide to Dinosaurs (3rd ed.). Princeton University Press.

    Source of the appearance features.

    paul2024a
  5. Norell, M. A.; Makovicky, P. J.; Bever, G. S.; Balanoff, A. M.; Clark, J. M.; Barsbold, R.; Rowe, T. (2009). A Review of the Mongolian Cretaceous Dinosaur Saurornithoides (Troodontidae: Theropoda). American Museum Novitates 3654: 1-63. American Museum of Natural History (BioOne sponsored). doi:10.1206/648.1

    Review of Mongolian troodontids recovered Byronosaurus as a troodontine near the base of the subfamily.

    norell2009a
  6. Tsuihiji, T.; Barsbold, R.; Watabe, M.; Tsogtbaatar, K.; Chinzorig, T.; Fujiyama, Y.; Suzuki, S. (2014). An exquisitely preserved troodontid theropod with new information on the palatal structure from the Upper Cretaceous of Mongolia. Naturwissenschaften 101(2): 131-142. Springer Science and Business Media LLC. doi:10.1007/s00114-014-1143-9

    New troodontid description's phylogeny bore on Byronosaurus's position near Saurornithoides-Zanabazar-Troodon clade.

    tsuihiji2014a
  7. Hartman, S.; Mortimer, M.; Wahl, W. R.; Lomax, D. R.; Lippincott, J.; Lovelace, D. M. (2019). A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight. PeerJ 7: e7247. PeerJ. doi:10.7717/peerj.7247

    Large paravian phylogeny bore on Byronosaurus's troodontine placement.

    hartman2019a