Skeletal reconstruction of Tawa hallae, together with selected individual bones. From Nesbitt et al. (2009), via Andrea Cau.

Belongs within: Dinosauria.
Contains: Neotheropoda.

The Theropoda are best known as the clade of primarily carnivorous dinosaurs. They also, through the birds, include the only dinosaurs to survive to the present day. However, the composition of this clade (defined by Baron et al., 2017, as all taxa closer to Passer than Diplodocus and Triceratops) outside the Neotheropoda remains contentious. Basal taxa such as Eoraptor are placed by some analyses outside the clade formed by the Theropoda and the Sauropodomorpha, while a few have placed them outside the dinosaurs entirely. Eoraptor lunensis and Eodromaeus murphi are known from the Late Triassic (Carnian) of Argentina.

Synapomorphies (from Baron et al. 2017): Premaxilla with posterodorsal process thin, blade-like; nasal possessing a posterolateral process enveloping part of anterior ramus of lacrimal; ventral rim of antorbital fossa ventrally sloped in its caudal part; descending process of lacrimal curved, subvertically oriented at its dorsal half; anterior ramus of jugal deeper than posterior ramus of jugal; parabasisphenoid with recess present; transverse groove running along dentary beneath and parallel to tooth row; splenial with foramen in ventral part; manual digit V absent; metacarpal I with lateral distal condyle strongly distally expanded relative to medial condyle; manual digit IV with one phalanx; ilium with ridge connecting posterior portion of supraacetabular rim to posterior portion of ilium; ilium with ischiadic peduncle well expanded posteriorly to anterior margin of postacetabular embayment; length of pubic peduncle of ilium less than twice craniocaudal width of its distal end (when excluding contribution of medioventral acetabular wall to craniocaudal width); ischial shaft distally expanded into distinct ‘foot’ or ‘boot’.

<==Theropoda [Herrerasauria, Herrerasauridae, Herreravia]
    |--+--Herrerasaurus Reig 1963KN20, L04 [incl. Frenguellisaurus Novas 1986L04, Ischisaurus Reig 1963L04]
    |  |    `--H. ischigualastensis Reig 1963 (see below for synonymy)L04
    |  `--+--Sanjuansaurus gordilloiBNB17
    |     `--Chindesaurus Long & Murry 1995NS09, L04 [incl. Caseosaurus Hunt, Lucas et al. 1998L04]
    |          `--C. bryansmalli Long & Murry 1995 [incl. Caseosaurus crosbyensis Hunt, Lucas et al. 1998]L04
    `--+--Staurikosaurus Colbert 1970KN20, L04
       |    `--S. pricei Colbert 1970L04
       `--+--Eoraptor Sereno, Forster et al. 1993KN20, L04
          |    `--E. lunensis Sereno, Forster et al. 1993L04
          `--+--Eodromaeus murphiBNB17
             |--Tawa Nesbitt, Smith et al. 2009NS09
             |    `--*T. hallae Nesbitt, Smith et al. 2009NS09
                `--Liliensternus Welles 1984BNB17, TR04
                     |--L. airelensis Cuny & Galton 1993TR04
                     |--L. liliensterni (Huene 1934) [=Halticosaurus liliensternus]TR04
                     `--L. orbitoangulatusD07
Theropoda incertae sedis:
  Compsosuchus Huene & Matley 1933WS03
    `--*C. solus Huene & Matley 1933WS03
  Aggiosaurus (n. d.)N85
  Arctosaurus Adams 1875 (n. d.)N85, M96
  Gwyneddosaurus (n. d.)N85
  Macrodontophion (n. d.)N85
  Pneumatoarthmus (n. d.)N85
  Calamosaurus foxii (Lydekker 1889) [=Calamospondylus foxii]N02
  Calamospondylus Fox in Anon. 1866 (n. d.)N02
    `--*C. oweni Fox in Anon. 1866 (n. d.)N02 [=Aristosuchus oweniP88]
  Aliwalia Galton 1985P88, L04
    `--A. rex Galton 1985L04
  Alwalkeria Chatterjee & Creisler 1994L04 [=Walkeria Chatterjee 1986P88, L04]
    `--A. maleriensis (Chatterjee 1986) [=Walkeria maleriensis]L04

Herrerasaurus ischigualastensis Reig 1963 [incl. Ischisaurus cattoi Reig 1963, Frenguellisaurus ischigualastensis Novas 1986 non H. ischigualastensis Reig 1963]L04

*Type species of generic name indicated


[BNB17] Baron, M. G., D. B. Norman & P. M. Barrett. 2017. A new hypothesis of dinosaur relationships and early dinosaur evolution. Nature 543: 501–506.

[D07] Dixon, D. 2007. The Complete Illustrated Encyclopedia of Dinosaurs & Prehistoric Creatures. Hermes House: London.

[KN20] Kammerer, C. F., S. J. Nesbitt, J. J. Flynn, L. Ranivoharimanana & A. R. Wyss. 2020. A tiny ornithodiran archosaur from the Triassic of Madagascar and the role of miniaturization in dinosaur and pterosaur ancestry. Proceedings of the National Academy of Sciences of the USA 117 (30): 17932–17936.

[L04] Langer, M. C. 2004. Basal Saurischia. In: Weishampel, D. B., P. Dodson & H. Osmólska (eds) The Dinosauria 2nd ed. pp. 25–46. University of California Press: Berkeley.

[M96] Marsh, O. C. 1896. The Dinosaurs of North America: Washington.

[N02] Naish, D. 2002. The historical taxonomy of the Lower Cretaceous theropods (Dinosauria) Calamospondylus and Aristosuchus from the Isle of Wight. Proceedings of the Geologists’ Association 113: 153–163.

[NS09] Nesbitt, S. J., N. D. Smith, R. B. Irmis, A. H. Turner, A. Downs & M. A. Norell. 2009. A complete skeleton of a Late Triassic saurischian and the early evolution of dinosaurs. Science 326: 1530–1533.

[N85] Norman, D. 1985 (reprinted 2000). The Illustrated Encyclopedia of Dinosaurs. Salamander Books: London.

[P88] Paul, G. S. 1988. Predatory Dinosaurs of the World: A Complete Illustrated Guide. Simon & Schuster: New York.

[TR04] Tykoski, R. S., & T. Rowe. 2004. Ceratosauria. In: Weishampel, D. B., P. Dodson & H. Osmólska (eds) The Dinosauria 2nd ed. pp. 47–70. University of California Press: Berkeley.

[WS03] Wilson, J. A., P. C. Sereno, S. Srivastava, D. K. Bhatt, A. Khosla & A. Sahni. 2003. A new abelisaurid (Dinosauria, Theropoda) from the Lameta Formation (Cretaceous, Maastrichtian) of India. Contributions from the Museum of Paleontology, The University of Michigan 31 (1): 1–42.

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