Open Paleo

Incisivosaurus

Xu et al., 2002 IN-si-SEE-vo-SOR-us

Named for its unusually large incisiform front teeth combined with Greek 'sauros' meaning 'lizard', hence 'incisor lizard'.

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

Incisivosaurus is a genus of small, probably herbivorous theropod dinosaurs from the early Cretaceous Period of what is now the People's Republic of China. The first specimen to be described (by Xu and colleagues in 2002), IVPP V13326, is a skull that was collected from the lowermost levels (the fluvial Lujiatun beds) of the Yixian Formation (dating to the Barremian stage about 126 million years ago) in the Sihetun area, near Beipiao City, in western Liaoning Province. The most significant, and highly unusual, characteristic of this dinosaur is its apparent adaptation to an herbivorous or omnivorous lifestyle. It was named for its prominent, rodent-like front teeth, which show wear patterns commonly found in plant-eating dinosaurs. The specific name gauthieri honors Dr. Jacques Gauthier, a pioneer of the phylogenetic method of classification.

Diagnosis

  1. Highly heterodont upper dentition with large incisiform first premaxillary tooth, smaller subconical second-fourth premaxillary teeth, and very small lanceolate maxillary teeth
  2. Large high-angled wear facets on mesial margins of teeth
  3. Longitudinal crest on ventral surface of basisphenoid
  4. Contact between accessory ventral flanges of pterygoids
  5. Subsidiary ectopterygoid fenestra present
  6. Triradiate palatine with very short maxillary process
  7. Relatively low skull with short preorbital region and toothed jaws for oviraptorosaur

Species

Incisivosaurus gauthieri Xu et al., 2002

Type species

Named for Dr. Jacques Gauthier, a pioneer of the phylogenetic method of classification.

Holotype
IVPP V13326 , Institute of Vertebrate Paleontology and Paleoanthropology
Material
Almost complete skull and partial cervical vertebra
Horizon
lower Yixian Formation, Barremian, Early Cretaceous , 125.8–121.4 million years ago
Locality
Lujiatun, Shangyuan, Beipiao City, Liaoning, China

References

  1. Xu, X.; Cheng, Y. N.; Wang, X. L.; Chang, C. H. (2002). An unusual oviraptorosaurian dinosaur from China. Nature 419(6904): 291-293. Springer Science and Business Media LLC. doi:10.1038/nature00966 xu2002d
  2. Zhong, Y.; Huyskens, M. H.; Yin, Q. Z.; Wang, Y.; Ma, Q.; Xu, Y. G. (2021). High-precision geochronological constraints on the duration of 'Dinosaur Pompeii' and the Yixian Formation. National Science Review 8(6): nwab063. doi:10.1093/nsr/nwab063

    Dates the base of the Yixian Formation, the Lujiatun Unit that yielded the holotype, to 125.755 Ma: Barremian on the ICS chart v2024/12 at its central value; its error reaches the Hauterivian.

    zhong2021a
  3. Gale, A. S.; Mutterlose, J.; Batenburg, S.; Gradstein, F. M.; Agterberg, F. P.; Ogg, J. G.; Petrizzo, M. R. (2020). The Cretaceous Period. Geologic Time Scale 2020 (Gradstein, F. M.; Ogg, J. G.; Schmitz, M. D.; Ogg, G. M., eds) 1023-1086. Elsevier, Amsterdam. doi:10.1016/B978-0-12-824360-2.00027-9

    Gives the GTS2020 Barremian span, 126.5 to 121.4 Ma; the ICS chart v2024/12 starts the stage at 125.77 Ma.

    gale2020a