Open Paleo

Eosinopteryx

Godefroit et al., 2013 EE-oh-si-NOP-ter-ix Disputed

From Greek eos, 'dawn/daybreak', + Latin Sinae, 'Chinese', + Greek pteryx, 'feather' or 'wing'; means 'dawn Chinese feather', referring to its early age and feathered Chinese specimen

165.3–149.2 million years ago Callovian–Kimmeridgian, Middle Jurassic–Late Jurassic
Middle Jurassic and Late Jurassic stages

Eosinopteryx is an extinct genus of theropod dinosaurs known to the Late Jurassic epoch of China. It contains a single species, Eosinopteryx brevipenna. Some researchers consider it a junior synonym of Anchiornis.

Under dispute

Eosinopteryx brevipenna is skeletally very similar to Anchiornis, and several workers have questioned its distinctness, treating it as a probable junior synonym of Anchiornis; Foth and colleagues (2025) removed it from their analysis, its character scores needing revision and its status questionable. Li and colleagues (2026), redescribing the holotype, attribute most of its diagnostic features to taphonomic deformation and damage and formally regard it as a junior synonym of Anchiornis huxleyi, probably an immature individual. Its position within the anchiornithid grade is otherwise stable.

Diagnosis

  1. Short snout, about 82% the length of the orbit
  2. Lacrimal with a long posterior process participating in about half the length of the dorsal margin of the orbit and a vestigial anterior process
  3. Short tail composed of only 20 caudal vertebrae, 2.7 times the length of the femur
  4. Chevrons reduced to small rod-like elements present only below the proximal 8th or 9th caudal vertebrae
  5. Ilium with a proportionally long, low and distally tapering postacetabular process (length/height at midlength ratio = 5)
  6. Pedal unguals shorter than the corresponding penultimate phalanges

Species

Eosinopteryx brevipenna Godefroit et al., 2013 Disputed

Type species

From Latin 'brevis' meaning 'short' and 'penna' meaning 'feather', referring to the reduced plumage preserved in the type specimen.

Holotype
PMOL-AD00134 , Paleontological Museum of Liaoning
Formerly
YFGP-T5197 (rehoused from Yizhou Fossil and Geology Park)
Material
Nearly complete articulated skeleton
Horizon
Tiaojishan Formation, Callovian–Kimmeridgian, Middle Jurassic–Late Jurassic , 165.3–149.2 million years ago
Locality
Yaolugou, Liaoning, China

References

  1. Godefroit, P.; Demuynck, H.; Dyke, G.; Hu, D.; Escuillié, F.; Claeys, P. (2013). Reduced plumage and flight ability of a new Jurassic paravian theropod from China. Nature Communications 4(1). Springer Science and Business Media LLC. doi:10.1038/ncomms2389 godefroit2013a
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

    Source of the body length, mass, and hip height estimates, and the appearance features.

    jones2026c
  3. Foth, C.; Rauhut, O. W. M. (2017). Re-evaluation of the Haarlem Archaeopteryx and the radiation of maniraptoran theropod dinosaurs. BMC Evolutionary Biology 17(1). Springer Science and Business Media LLC. doi:10.1186/s12862-017-1076-y

    Placed Eosinopteryx within Anchiornithidae in reassessment of basal paravians.

    foth2017a
  4. Xu, L.; Wang, M.; Chen, R.; Dong, L.; Lin, M.; Xu, X.; Tang, J.; You, H.; Zhou, G.; Wang, L.; He, W.; Li, Y.; Zhang, C.; Zhou, Z. (2023). A new avialan theropod from an emerging Jurassic terrestrial fauna. Nature 621(7978): 336-343. Springer Science and Business Media LLC. doi:10.1038/s41586-023-06513-7

    Recovered Eosinopteryx within Anchiornithidae, questioning its validity relative to Anchiornis.

    xu2023a
  5. Foth, C.; van de Kamp, T.; Tischlinger, H.; Kantelis, T.; Carney, R. M.; Zuber, M.; Hamann, E.; Wallaard, J. J. W.; Lenz, N.; Rauhut, O. W. M.; Frey, E. (2025). A new Archaeopteryx from the lower Tithonian Mörnsheim Formation at Mühlheim (Late Jurassic). Fossil Record 28(1): 17-43. doi:10.3897/fr.28.131671

    Removed Eosinopteryx from its phylogenetic matrix, its character scores needing revision and its taxonomic status questionable.

    foth2025a
  6. Li, F.-F.; Hu, D.-Y.; Zhao, C.-L.; Li, Z.-H.; Zhou, Z.-H. (2026). Redescription and taxonomic reassessment of the holotype of anchiornithine Eosinopteryx brevipenna. Palaeoworld 35(6): 201180. doi:10.1016/j.palwor.2026.201180

    Redescribes the holotype and regards Eosinopteryx brevipenna as a junior synonym of Anchiornis huxleyi, most of its diagnostic features taphonomic.

    li2026a