Open Paleo

Daliansaurus

Shen et al., 2017 DAH-ly-uhn-SOR-us

Named after Dalian, a city in Liaoning Province, China, + Greek sauros ('lizard' or 'reptile'), meaning 'Dalian reptile'.

125.8–121.4 million years ago Barremian, Early Cretaceous
Early Cretaceous stages

Daliansaurus is a genus of small troodontid theropod dinosaur, measuring approximately 1 meter (3 ft 3 in) long, from the Early Cretaceous of China. It contains a single species, D. liaoningensis, named in 2017 by Shen and colleagues from a nearly complete skeleton preserved in three dimensions. Daliansaurus is unusual in possessing an enlarged claw on the fourth digit of the foot, in addition to the "sickle claw" found on the second digit of the feet of most paravians. It also has long metatarsal bones, and apparently possesses bird-like uncinate processes (a first among troodontids). In the Lujiatun Beds of the Yixian Formation, a volcanically-influenced region with a cold climate, Daliansaurus lived alongside its closest relatives — Sinovenator, Sinusonasus, and Mei, with which it forms the group Sinovenatorinae.

Under dispute

Daliansaurus was described as a member of Sinovenatorinae, the sister of Sinusonasus (Shen and colleagues, 2017), but every later analysis recovers it in a more derived position, outside that subfamily (Hartman and colleagues, 2019; Cau and Madzia, 2021; Sellés and colleagues, 2021; Wang and colleagues, 2023; Kubota and colleagues, 2024).

Diagnosis

  1. Ungual of pedal digit IV is robust, dorsoventrally deep, and approximately the same size as the sickle-shaped ungual of pedal digit II (unique among troodontids).
  2. Uncinate processes present on the dorsal ribs (not previously reported in troodontids).
  3. Metatarsal IV lacks a prominent longitudinal lateroventral flange (unlike Sinovenator and Sinusonasus).
  4. Ventral surface of the postacetabular process of the ilium is strongly concave in lateral view (not nearly straight as in Sinovenator and Mei).
  5. Metatarsal II so short it terminates before the trochlea of metatarsal IV begins (unlike Sinovenator and Sinusonasus).
  6. Metacarpal II is slightly shorter than metacarpal III (instead of longer, as in Sinovenator and Sinusonasus).

Species

Daliansaurus liaoningensis Shen et al., 2017

Type species

Named for Liaoning Province in northeastern China, where the fossil was discovered.

Holotype
DNHM D2885 , Xinghai Paleontological Museum of Dalian
Material
Nearly complete skeleton with estimated total body length of 1 meter.
Horizon
Yixian Formation, Barremian, Early Cretaceous , 125.8–121.4 million years ago
Locality
Lujiatun, Liaoning, China

References

  1. Shen, C.; Lü, J.; Liu, S.; Kundrát, M.; Brusatte, S. L.; Gao, H. (2017). A New Troodontid Dinosaur from the Lower Cretaceous Yixian Formation of Liaoning Province, China. Acta Geologica Sinica (English Edition) 91(3): 763-780. Wiley. doi:10.1111/1755-6724.13307

    Named Daliansaurus and erected Sinovenatorinae, recovering it as the sister of Sinusonasus.

    shen2017b
  2. Paul, G. S. (2024). The Princeton Field Guide to Dinosaurs (3rd ed.). Princeton University Press.

    Source of the mass estimate.

    paul2024a
  3. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

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

    jones2026c
  4. 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

    Recovered Daliansaurus outside Sinovenatorinae; forcing it in costs four steps.

    hartman2019a
  5. Cau, A.; Madzia, D. (2021). The phylogenetic affinities and morphological peculiarities of the bird-like dinosaur Borogovia gracilicrus from the Upper Cretaceous of Mongolia. PeerJ 9: e12640. PeerJ. doi:10.7717/peerj.12640

    Recovered Daliansaurus outside Sinovenatorinae.

    cau2021a
  6. Sellés, A. G.; Vila, B.; Brusatte, S. L.; Currie, P. J.; Galobart, À. (2021). A fast-growing basal troodontid (Dinosauria: Theropoda) from the latest Cretaceous of Europe. Scientific Reports 11(1). Springer Science and Business Media LLC. doi:10.1038/s41598-021-83745-5

    Recovered Daliansaurus as the sister of Tochisaurus.

    sellés2021a
  7. Wang, X.; Cau, A.; Wang, Z.; Yu, K.; Wu, W.; Wang, Y.; Liu, Y. (2023). A new theropod dinosaur from the Lower Cretaceous Longjiang Formation of Inner Mongolia (China). Cretaceous Research 151. Elsevier BV. doi:10.1016/j.cretres.2023.105605

    Recovered Daliansaurus as the sister of the late-diverging troodontids.

    wang2023a
  8. Kubota, K.; Kobayashi, Y.; Ikeda, T. (2024). Early Cretaceous troodontine troodontid (Dinosauria: Theropoda) from the Ohyamashimo Formation of Japan reveals the early evolution of Troodontinae. Scientific Reports 14(1). Springer Science and Business Media LLC. doi:10.1038/s41598-024-66815-2

    Recovered Daliansaurus outside Sinovenatorinae.

    kubota2024a