Open Paleo

Saurischia

Seeley, 1888

Its genera lived 237.0–66.0 million years ago Late Triassic–Late Cretaceous

Saurischia, meaning "lizard-hipped," is one of the two major divisions of dinosaurs, distinguished from the ornithischians by hip structure. Its members retain the ancestral, three-pronged pelvic arrangement in which the pubis points forward, the same configuration seen in modern lizards and other reptiles, rather than the backward-rotated pubis of ornithischians. The group encompasses the mostly carnivorous, typically bipedal theropods together with the long-necked, herbivorous sauropodomorphs, and because birds are a lineage of maniraptoran theropods, they too fall within Saurischia. It is defined as birds and all dinosaurs more closely related to them than to Triceratops (Sereno, 1998); Gauthier (1986) had defined it against Ornithischia as a whole. All saurischians except birds died out in the Cretaceous-Paleogene extinction event at the end of the Cretaceous, while birds survive as the clade's only living descendants.

Diagnosis

  1. Forward-pointing (anteroventrally directed) pubis in basal members
  2. Elongate, mobile neck with cervical vertebrae bearing well-developed pleurocoels
  3. Asymmetrical hand with digit II longest
  4. Subnarial foramen present between premaxilla and maxilla

Clades within Saurischia

Genera placed directly in Saurischia

  • Chindesaurus Long & Murry, 1995 Norian (227.3–205.7 Ma)United Statesincertae sedisunder dispute
  • Daemonosaurus Sues et al., 2011 Rhaetian (205.7–201.4 Ma)United Statesincertae sedisunder dispute
  • Eshanosaurus Xu et al., 2001 Hettangian (201.4–199.5 Ma)Chinaincertae sedisunder dispute
  • Tawa Nesbitt et al., 2009 Norian (227.3–205.7 Ma)United Statesincertae sedisunder dispute
  • Velocipes Nomen dubium Huene, 1932 Norian (227.3–205.7 Ma)Polandincertae sedisunder dispute

References

  1. Seeley, H. G. (1888). On the classification of the fossil animals commonly named Dinosauria. Proceedings of the Royal Society of London 43: 165-171. doi:10.1098/rspl.1887.0117 seeley1888b
  2. Sereno, P. C. (1998). A rationale for phylogenetic definitions, with application to the higher-level taxonomy of Dinosauria. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 210: 41-83. doi:10.1127/njgpa/210/1998/41

    Defined Saurischia as all dinosaurs closer to Neornithes than to Triceratops.

    sereno1998a
  3. Gauthier, J. A. (1986). Saurischian monophyly and the origin of birds. Memoirs of the California Academy of Sciences 8: 1-55.

    Defined Saurischia as birds and all dinosaurs closer to birds than to Ornithischia.

    gauthier1986a