Open Paleo

Sinosaurus

Young, 1940 SIEN-o-SOR-us

From Latin Sinae, "Chinese", combined with Greek sauros, "lizard" — means "Chinese lizard"

201.4–192.9 million years ago Hettangian–Sinemurian, Early Jurassic
Early Jurassic stages

Sinosaurus is an extinct genus of basal theropod dinosaur which lived during the Early Jurassic (Hettangian-Sinemurian). Fossils of the animal have been found in the Lufeng Formation, in the Yunnan Province of China. The type species, S. triassicus, was named by Chung Chieng Young in 1940. A second species, S. sinensis, was originally assigned to Dilophosaurus, but was later reassigned to Sinosaurus. Sinosaurus is morphologically similar to Dilophosaurus including the presence of a similarly shaped cranial crest, though its precise taxonomic position is uncertain, and the two genera may not be closely related.

Under dispute

Sinosaurus triassicus is a basal neotheropod of uncertain position. Carrano and colleagues (2012) recovered it as a basal tetanuran inside Averostra, but other analyses place it outside Averostra near Dilophosaurus and Cryolophosaurus (Smith and colleagues, 2007; Rauhut and colleagues, 2024), and Xing (2012) leaves it in a polytomy with Tetanurae. It is placed conservatively at Neotheropoda incertae sedis. The species "Dilophosaurus" sinensis is referred to Sinosaurus.

Diagnosis

  1. Longitudinal ridge on the lateral surface of the maxilla, dorsal to the alveolar line
  2. Vertical nasomaxillary crest developed dorsoventrally from the ventral portion of the maxilla to the nasal crest
  3. Anterior process of the jugal forming most of the ventral border of the antorbital fenestra, more than half its total length
  4. Fenestra between the nasal, lacrimal, and prefrontal

Species

Sinosaurus triassicus Young, 1940

Type species

From 'Triassic', the geological period from which the fossils were originally thought to date, with the Latin adjectival suffix '-icus'.

Holotype
IVPP V34 , Institute of Vertebrate Paleontology and Paleoanthropology
Material
Left maxilla fragment with four teeth, two other jaw fragments, and three isolated teeth
Horizon
Lufeng Formation, Hettangian–Sinemurian, Early Jurassic , 201.4–192.9 million years ago
Locality
Huangchiatien, Yunnan, China Young (1948) gives the holotype's horizon only as the Red beds of Huangchiatien, while specifying the Dark Red Beds for Lukousaurus from the same village. Xing (2012) places the species in the Shawan Member, but his locality table assigns IVPP V30 and V31 to this site when Young reports them from Mahuangching, about 60 km west. The member is therefore unresolved.

Notable specimens

  • LFKL 004

    Dinosaur Fossil Research and Protection Center of Lufeng City complementary

    A near-complete Sinosaurus triassicus skull with a total length of 51.96 cm from premaxilla to quadratojugal, preserving the paired nasal-lacrimal crests and skull anatomy far beyond the fragmentary type material.

    Zhang et al. (2023)

  • ZLJT01

    Lufeng World Dinosaur Valley ontogeny

    A juvenile individual referred to Sinosaurus, comprising cranial elements including both frontals, parietals, an incomplete braincase and dentary, plus an atlantal intercentrum and other postcranial fragments, documenting an early growth stage of the taxon.

    Xing (2012)

  • ZLJ 0003, ZLJ 0057

    Lufeng World Dinosaur Valley most complete

    Two specimens referred to Sinosaurus that are each almost complete, providing the most complete known skeletal data for the genus after most historically referred postcrania were reassigned to other genera.

    Liang et al. (2024)

References

  1. Zhang, Z. C.; Wang, T.; You, H. L. (2023). A new specimen of Sinosaurus triassicus (Dinosauria: Theropoda) from the Early Jurassic of Lufeng, Yunnan, China. Historical Biology 36(4): 857-871. doi:10.1080/08912963.2023.2190760

    Source of the revised diagnosis; the maxillary ridge is drawn from the holotype, the other three characters from the referred skull LFKL 004.

    zhang2023a
  2. Xing, L. D. (2012). Sinosaurus from Southwestern China. Masters thesis, University of Alberta. doi:10.7939/R3HP8F

    Master's thesis.

    xing2012b
  3. Liang, Q.; Falkingham, P. L.; Xing, L. (2024). Virtual skeleton and body mass for revealing the life strategies of Sinosaurus. Historical Biology 1-15. doi:10.1080/08912963.2024.2385615 liang2024a
  4. Young, C. C. (1940). Preliminary notes on the Lufeng vertebrate fossils. Bulletin of the Geological Society of China 20(3-4): 235-239. doi:10.1111/j.1755-6724.1940.mp203-4003.x

    Preliminary faunal notice coining Sinosaurus triassicus as gen. et sp. nov., with a combined description of the new genus and its single included new species and a statement of tooth characters.

    young1940a
  5. Young, C. C. (1948). On two new saurischians from Lufeng, Yunnan. Bulletin of the Geological Society of China 28(1-2): 75-90. Wiley. doi:10.1111/j.1755-6724.1948.mp281-2007.x

    Full description of the type maxilla and jaw fragments, with the catalog number and a diagnosis the 1940 notice lacked.

    young1948a
  6. Wang, G. F.; You, H. L.; Pan, S. G.; Wang, T. (2017). A new crested theropod dinosaur from the Early Jurassic of Yunnan Province, China. Vertebrata PalAsiatica 55(2): 177-186.

    Reports Sinosaurus as recovered both as a basal tetanuran and near the base of Averostra.

    wang2017b
  7. Carrano, M. T.; Benson, R. B. J.; Sampson, S. D. (2012). The phylogeny of Tetanurae (Dinosauria: Theropoda). Journal of Systematic Palaeontology 10(2): 211-300. Informa UK Limited. doi:10.1080/14772019.2011.630927

    Tetanurae phylogeny analysis recovered Sinosaurus as a basal tetanuran within Averostra

    carrano2012a
  8. Rauhut, O. W. M. (2003). The interrelationships and evolution of basal theropod dinosaurs. Special Papers in Palaeontology 69: 1-213. The Palaeontological Association.

    Excluded "Dilophosaurus" sinensis from its analysis as too poorly known to code.

    rauhut2003b
  9. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

    Treats Sinosaurus as a stem-averostran.

    jones2026c
  10. Smith, N. D.; Makovicky, P. J.; Hammer, W. R.; Currie, P. J. (2007). Osteology of Cryolophosaurus ellioti (Dinosauria: Theropoda) from the Early Jurassic of Antarctica and implications for early theropod evolution. Zoological Journal of the Linnean Society 151(2): 377-421. doi:10.1111/j.1096-3642.2007.00325.x

    Recovered "Dilophosaurus" sinensis outside Averostra.

    smith2007b
  11. Rauhut, O. W. M.; Bakirov, A. A.; Wings, O.; Fernandes, A. E.; Hübner, T. R. (2024). A new theropod dinosaur from the Callovian Balabansai Formation of Kyrgyzstan. Zoological Journal of the Linnean Society 201(4). Oxford University Press (OUP). doi:10.1093/zoolinnean/zlae090

    Recovered "Dilophosaurus" sinensis outside Averostra.

    rauhut2024a