Open Paleo

Anchiornithidae

Foth & Rauhut, 2017 Type genus Anchiornis

Its genera lived 165.3–149.2 million years ago Middle Jurassic–Late Jurassic
Middle Jurassic and Late Jurassic stages

Anchiornithidae is a family of small, lightly built, feathered paravian theropod dinosaurs known mostly from the Late Jurassic of China, with the majority of fossils coming from the Tiaojishan Formation of Liaoning. Members include Anchiornis, Aurornis, Eosinopteryx and Fujianvenator (Xu and colleagues, 2023) and Ostromia from Germany (Foth and Rauhut, 2017); Xiaotingia and Pedopenna fall inside the family in some analyses (Foth and Rauhut, 2017; Xu and colleagues, 2023) and outside it in others (Rauhut and colleagues, 2019). These were long-legged, long-armed carnivores similar in build to Archaeopteryx and early troodontids. Anchiornis carried large pennaceous feathers on its legs as well as its arms, the arm feathers small with thin rachides and symmetrical vanes (Hu and colleagues, 2009), whereas Eosinopteryx lacks them on the tail, metatarsus and foot (Godefroit and colleagues, 2013). The group's exact place among paravians is unsettled, having been recovered at various times as the earliest-branching birds, as basal members of Troodontidae, or as part of Archaeopterygidae, and membership at the edges of the clade remains unstable.

Under dispute

The phylogenetic position of Anchiornithidae is unresolved. It is most often recovered as the earliest-diverging clade within Avialae (Foth and Rauhut, 2017; Pei and colleagues, 2020; Xu and colleagues, 2023), but several analyses instead place the anchiornithids within Deinonychosauria, either as basal troodontids (Turner and colleagues, 2012) or as archaeopterygid-grade deinonychosaurs (Xu and colleagues, 2011; Hartman and colleagues, 2019), and one analysis places them as basal paravians outside Eumaniraptora (Lefèvre and colleagues, 2017). Cau (2024) recovers the anchiornithids not as a clade at all but as a paraphyletic grade of avialans leading to Scansoriopterygidae. Membership at the edges of the clade is likewise unstable, with Xiaotingia and Pedopenna variously included or excluded (Foth and Rauhut, 2017; Rauhut and colleagues, 2019), and support values are generally low (Foth and Rauhut, 2017).

Diagnosis

  1. Extensive pennaceous feathering on the hindlimb forming a hindwing
  2. Elongate, gracile hindlimbs with an unspecialized, non-raptorial pes
  3. Skull with a subtriangular profile and numerous small, closely spaced teeth
  4. Forelimb shorter than in Archaeopteryx and later avialans

Genera placed directly in Anchiornithidae

  • Anchiornis Xu et al., 2009 Callovian–Kimmeridgian (165.3–149.2 Ma)China
  • Aurornis Godefroit et al., 2013 Callovian–Kimmeridgian (165.3–149.2 Ma)Chinaunder dispute
  • Caihong Hu et al., 2018 Oxfordian (161.5–154.8 Ma)China
  • Eosinopteryx Disputed Godefroit et al., 2013 Callovian–Kimmeridgian (165.3–149.2 Ma)China
  • Fujianvenator Xu et al., 2023 Kimmeridgian (154.8–149.2 Ma)China
  • Serikornis Lefèvre et al., 2017 Oxfordian (161.5–154.8 Ma)Chinaunder dispute

References

  1. 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

    Erected Anchiornithidae as a stem-based clade and recovered it as the basal-most avialan group, containing Anchiornis, Xiaotingia, Eosinopteryx and allies.

    foth2017a
  2. Pei, R.; Pittman, M.; Goloboff, P. A.; Dececchi, T. A.; Habib, M. B.; Kaye, T. G.; Larsson, H. C. E.; Norell, M. A.; Brusatte, S. L.; Xu, X. (2020). Potential for Powered Flight Neared by Most Close Avialan Relatives, but Few Crossed Its Thresholds. Current Biology 30(20): 4033-4046.e8. Elsevier BV. doi:10.1016/j.cub.2020.06.105

    Large paravian phylogenetic analysis recovering Anchiornithidae as earliest-diverging avialan clade.

    pei2020a
  3. 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

    New avialan theropod description supporting Anchiornithidae's placement within Avialae.

    xu2023a
  4. Turner, A. H.; Makovicky, P. J.; Norell, M. A. (2012). A Review of Dromaeosaurid Systematics and Paravian Phylogeny. Bulletin of the American Museum of Natural History 371: 1-206. doi:10.1206/748.1

    Dromaeosaurid/paravian phylogeny review recovering anchiornithids as basal troodontids.

    turner2012a
  5. 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

    Nested Anchiornis with Archaeopteryx in an expanded Archaeopterygidae recovered as deinonychosaurs, rejecting a stemward paravian position at 15 steps.

    hartman2019a
  6. Xu, X.; You, H.; Du, K.; Han, F. (2011). An Archaeopteryx-like theropod from China and the origin of Avialae. Nature 475(7357): 465-470. Springer Science and Business Media LLC. doi:10.1038/nature10288

    Recovered Archaeopteryx among deinonychosaurs close to anchiornithids in a paravian phylogeny.

    xu2011d
  7. Cau, A. (2024). A Unified Framework for Predatory Dinosaur Macroevolution. Bollettino della Società Paleontologica Italiana 63(1): 1-19. doi:10.4435/BSPI.2024.08

    Recovered the anchiornithids as a paraphyletic grade of avialans leading to Scansoriopterygidae rather than as a clade; no support values are reported.

    cau2024a
  8. Lefèvre, U.; Cau, A.; Cincotta, A.; Hu, D.; Chinsamy, A.; Escuillié, F.; Godefroit, P. (2017). A new Jurassic theropod from China documents a transitional step in the macrostructure of feathers. The Science of Nature 104(9-10). Springer Science and Business Media LLC. doi:10.1007/s00114-017-1496-y

    Phylogenetic analysis placed Serikornis and allied taxa as basal paravians outside Eumaniraptora

    lefèvre2017a
  9. Hu, D.; Hou, L.; Zhang, L.; Xu, X. (2009). A pre-Archaeopteryx troodontid theropod from China with long feathers on the metatarsus. Nature 461(7264): 640-643. Springer Science and Business Media LLC. doi:10.1038/nature08322

    Described Anchiornis, with large pennaceous feathers on the forearm, hand, lower leg and metatarsus and symmetrical remiges.

    hu2009a
  10. 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

    Described Eosinopteryx, which lacks large pennaceous feathers on the tail, metatarsus and foot.

    godefroit2013a
  11. Rauhut, O. W. M.; Tischlinger, H.; Foth, C. (2019). A non-archaeopterygid avialan theropod from the Late Jurassic of southern Germany. eLife 8: e43789. eLife Sciences Publications, Ltd. doi:10.7554/elife.43789

    Described Alcmonavis and restricted Anchiornithidae to Eosinopteryx, Ostromia and Anchiornis, with Pedopenna and Xiaotingia basal to Archaeopteryx.

    rauhut2019b