Ceratopsia

Skeletal mounts of Psittacosaurus mongoliensis, copyright Ninjatacoshell.

Belongs within: Genasauria.
Contains: Ceratopsidae.

The Ceratopsia are a group of herbivorous dinosaurs known from the Late Jurassic to Cretaceous of Asia and North America (with some less definite records from other parts of the world). Members of this group are characterised by a novel bone, the rostral bone, at the front of the upper jaw (which forms a narrow beak), and a tendency to the develop of a frill on the rear margin of the skull (You & Dodson 2004).

See also: Big horned lizards; Ceratopsids: a Cretaceous flash in the pan.

Synapomorphies (from You & Dodson 2004): External naris high, separated from ventral border of premaxilla by flat area; rostral bone present; premaxilla enlarged; jugal with well-developed lateral flaring; wide dorsoventral length of infraorbital ramus of jugal; palatal extensions of maxillae contacting rostral to choana.

<==Ceratopsia
    |  i. s.: Micropachycephalosaurus Dong 1978 ZY09, MCW04
    |           `--M. hongtuyanensis Dong 1978 MCW04
    |--Psittacosaurus Osborn 1923 [incl. Protiguanodon Osborn 1923] YD04
    |    |--P. guyangensis Cheng 1983 YD04
    |    |--P. mazongshanensis Xu 1997 YD04
    |    |--P. meileyingensis Sereno, Chao et al. 1988 YD04
    |    |--P. mongoliensis Osborn 1923 (see below for synonymy) YD04
    |    |--P. neimongoliensis Russell & Zhao 1996 YD04
    |    |--P. ordosensis Russell & Zhao 1996 YD04
    |    |--P. osborni Young 1931 [incl. P. tingi Young 1931] YD04
    |    |--P. sattayaraki Buffetaut & Suteethorn 1992 (n. d.) YD04
    |    |--P. sinensis Young 1958 YD04
    |    |--P. xinjiangensis Sereno & Chao 1988 YD04
    |    `--P. youngi Chao 1962 YD04
    `--Neoceratopsia [Protoceratopidae, Protoceratopoidea] YD04
         |  i. s.: Microceratops YD04
         |           |--M. gobiensis Bohlin 1953 (n. d.) YD04
         |           `--M. sulcidens Bohlin 1953 (n. d.) YD04
         |         Kulceratops kulensis Nessov 1995 (n. d.) YD04
         |         Yamaceratops dorngobiensis BN08
         |         Bainoceratops efremovi T08
         |--Yinlong downsi BSN07
         `--+--Chaoyangsaurus Zhao, Cheng & Xu 1999 YD04
            |    `--C. youngi Zhao, Cheng & Xu 1999 YD04
            `--+--Liaoceratops Xu, Makovicky et al. 2002 XM02
               |    `--*L. yanzigouensis Xu, Makovicky et al. 2002 XM02
               `--+--Archaeoceratops Dong & Azuma 1997 [Archaeoceratopidae] YD04
                  |    `--A. oshimai Dong & Azuma 1997 YD04
                  `--Coronosauria YD04
                       |--Ceratopsoidea YD04
                       |    |--+--Ceratopsidae YD04
                       |    |  `--Zuniceratops Wolfe & Kirkland 1998 YD04
                       |    |       `--Z. christopheri Wolfe & Kirkland 1998 YD04
                       |    `--+--Asiaceratops salsopaludalis Nessov, Kaznyshkina & Cherepanov 1989 (n. d.) XM02, YD04
                       |       `--Leptoceratopsidae YD04
                       |            |--Montanoceratops Sternberg 1951 YD04
                       |            |    `--M. cerorhynchus (Brown & Schlaikjer 1942) [=Leptoceratops cerorhynchus] YD04
                       |            `--+--Leptoceratops Brown 1914 YD04
                       |               |    `--L. gracilis Brown 1914 YD04
                       |               `--Udanoceratops Kurzanov 1992 XM02, YD04
                       |                    `--U. tschizhovi Kurzanov 1992 YD04
                       `--Protoceratopsidae YD04
                            |--Graciliceratops Sereno 2000 YD04
                            |    `--G. mongoliensis Sereno 2000 YD04
                            |--Protoceratops Granger & Gregory 1923 YD04
                            |    |--P. andrewsi Granger & Gregory 1923 YD04
                            |    `--P. hellenikorhinus Lambert, Godefroit et al. 2001 YD04
                            `--Bagaceratopidae A03
                                 |--Bagaceratops Maryańska & Osmólska 1975 [incl. Breviceratops Kurzanov 1990] YD04
                                 |    `--B. rozhdestvenskyi Maryańska & Osmólska 1975 (see below for synonymy) YD04
                                 |--Lamaceratops Alifanov 2003 A03
                                 |    `--*L. tereschenkoi Alifanov 2003 A03
                                 `--Platyceratops Alifanov 2003 A03
                                      `--*P. tatarinovi Alifanov 2003 A03

Bagaceratops rozhdestvenskyi Maryańska & Osmólska 1975 [incl. Protoceratops kozlowskii Maryańska & Osmólska 1975, Breviceratops kozlowskii] YD04

Psittacosaurus mongoliensis Osborn 1923 [incl. Protiguanodon mongoliensis Osborn 1923, Ps. protiguanodonensis Young 1958] YD04

*Type species of generic name indicated

REFERENCES

[A03] Alifanov, V. R. 2003. Two new dinosaurs of the infraorder Neoceratopsia (Ornithischia) from the Upper Cretaceous of the Nemegt Depression, Mongolian People’s Republic. Paleontologicheskii Zhurnal 2003 (5): 77–88 (transl. Paleontological Journal 37 (5): 524–534).

[BN08] Balanoff, A. M., M. A. Norell, G. Grellet-Tinner & M. R. Lewin. 2008. Digital preparation of a probable neoceratopsian preserved within an egg, with comments on microstructural anatomy of ornithischian eggshells. Naturwissenschaften 95: 493–500.

[BSN07] Butler, R. J., R. M. H. Smith & D. B. Norman. 2007. A primitive ornithischian dinosaur from the Late Triassic of South Africa, and the early evolution and diversification of Ornithischia. Proceedings of the Royal Society of London Series B—Biological Sciences 274 (1621): 2041–2046.

[MCW04] Maryańska, T., R. E. Chapman & D. B. Weishampel. 2004. Pachycephalosauria. In: Weishampel, D. B., P. Dodson & H. Osmólska (eds) The Dinosauria 2^nd ed. pp. 464–477. University of California Press: Berkeley.

[T08] Tereschenko, V. S. 2008. Adaptive features of protoceratopoids (Ornithischia: Neoceratopsia). Paleontologicheskii Zhurnal 2008 (3): 50–64.

[XM02] Xu, X., P. J. Makovicky, X.-L. Wang, M. A. Norell & H.-L. You. 2002. A ceratopsian dinosaur from China and the early evolution of Ceratopsia. Nature 416: 314–317.

[YD04] You H. & P. Dodson. 2004. Basal Ceratopsia. In: Weishampel, D. B., P. Dodson & H. Osmólska (eds) The Dinosauria 2^nd ed. pp. 478–493. University of California Press: Berkeley.

[ZY09] Zheng, X.-T., H.-L. You, X. Xu & Z.-M. Dong. 2009. An Early Cretaceous heterodontosaurid dinosaur with filamentous integumentary structures. Nature 458: 333–336.