Open Paleo

Shishugounykus

Qin et al., 2019 shih-shoo-GOH-NY-kus

Named after the Shishugou Formation where it was found, combined with Greek onyx/onykos, "claw" — means "Shishugou claw"

165.3–154.8 million years ago Callovian–Oxfordian, Middle Jurassic–Late Jurassic
Middle Jurassic and Late Jurassic stages

Shishugounykus is a genus of basal alvarezsaurian dinosaur from the Shishugou Formation of Xinjiang, China. The type and only species is Shishugounykus inexpectus. The specific name refers to the unexpected discovery of another species of alvarezsaur from the Shishugou Formation (other alvarezsaurs from this formation include Haplocheirus and possibly Aorun). Its affinities to alvarezsaurs have subsequently been questioned.

Under dispute

Shishugounykus inexpectus was described as an early-diverging alvarezsaurian (Qin and colleagues, 2019) and recovered as the earliest-diverging member of the group by Meso and colleagues (2024). Agnolín and colleagues (2021) questioned this, arguing that the Jurassic Chinese "alvarezsauroids" (Shishugounykus with Haplocheirus and Aorun) may instead have ornithomimosaur or compsognathid affinities.

Diagnosis

  1. Scapula with hollow acromial process but without lateral concavities
  2. Humeral internal tuberosity mediolaterally constricted distally, giving it a pinched appearance
  3. Iliac medial surface with step-wise transition from ischial peduncle to pubic peduncle
  4. Distal end of metatarsal II asymmetrically ginglymoid
  5. Supratemporal fossa occupying large portion of frontal with indistinct anterior border
  6. Metacarpal III straight in dorsal view
  7. Ungual III-3 subequal in size to ungual II-2

Species

Shishugounykus inexpectus Qin et al., 2019

Type species

From Latin 'inexpectus' meaning 'unexpected', referring to the unexpected discovery of another alvarezsaurian species from the Shishugou Formation.

Holotype
IVPP V23567 , Institute of Vertebrate Paleontology and Paleoanthropology
Material
A partial skeleton including several cranial elements, three dorsal vertebrae, four sacral vertebrae, three caudal vertebrae, partial scapula, partial humerus, partial ulna and radius, nearly complete manus, partial ilium, ischium, and pubis, complete right femur, partial left femur, nearly complete tibiae, partial fibula, partial metatarsals II and III, pedal phalanges, and rib fragments.
Horizon
Shishugou Formation, Callovian–Oxfordian, Middle Jurassic–Late Jurassic , 165.3–154.8 million years ago
Locality
Wucaiwan, Xinjiang, China Qin and colleagues (2019) place the holotype between two tuffs, dated 161.2 and 158.7 Ma on the older calibration, which on the ICS chart v2024/12 straddle the base of the Oxfordian.

References

  1. Qin, Z.; Clark, J.; Choiniere, J.; Xu, X. (2019). A new alvarezsaurian theropod from the Upper Jurassic Shishugou Formation of western China. Scientific Reports 9(1). Springer Science and Business Media LLC. doi:10.1038/s41598-019-48148-7 qin2019a
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

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

    jones2026c
  3. Agnolín, F. L.; Lü, J. C.; Kundrát, M.; Xu, L. (2021). Alvarezsaurid osteology: new data on cranial anatomy. Historical Biology 34(3): 443-452. doi:10.1080/08912963.2021.1929203

    Argued Jurassic Chinese alvarezsauroids may instead show ornithomimosaur or compsognathid affinities

    agnolín2021b
  4. Meso, J. G.; Pol, D.; Chiappe, L.; Qin, Z.; Díaz-Martínez, I.; Gianechini, F.; Apesteguía, S.; Makovicky, P. J.; Pittman, M. (2024). Body size and evolutionary rate analyses reveal complex evolutionary history of Alvarezsauria. Cladistics 41(2): 135-155. Wiley. doi:10.1111/cla.12600

    Recovered Shishugounykus as the earliest-diverging member of the group.

    meso2024a