Fossilised skeleton and reconstruction of Protosuchus richardsoni, photographed by Ryan Somma.

Belongs within: Crocodylomorpha.
Contains: Metasuchia.

The Crocodyliformes correspond to the ‘Crocodylia’ of many earlier authors (with the latter generally now restricted to the crown group of crocodilians). The basalmost forms, the protosuchians, were still relatively lightly built taxa, though undeniably crocodile-like. Members of the basal lineage including modern species, the Mesoeucrocodylia, are united by the fusion of the frontal bones of the skull, together with the development of a secondary palate from the posterior extension of the palatine bones.

Synapomorphies (from Benton & Clark 1988): Otoccipital contacting ventromedial part of quadrate, enclosing carotid artery and forming passage for cranial nerves IX-XI; basisphenoid rostrum dorsoventrally expanded; basipterygoid process reduced, basipterygoid joint closed suturally; pterygoid extending dorsally, forming ventrolateral edge of trigeminal foramen; otoccipitals broadly meeting dorsal to foramen magnum; eustachian tubes enclosed between basioccipital and basisphenoid; antorbital fenestra much smaller than orbit; premaxilla and maxilla sutured together along butt joint; parietal lacking broad occipital portion; ventromedial end of coracoid anteroposteriorly expanded, anterior edge concave; quadrate hollow with several fenestrae on dorsal surface; mastoid antrum extending through supraoccipital; two large palpebrals present; dorsal head of quadrate contacting laterosphenoid; skull table in temporal region with nearly flat dorsal surface; postorbital medial to jugal on postorbital bar; scapula dramatically broadening dorsally.

Crocodyliformes [Crocodilia]
    |--Mesoeucrocodylia [Mesosuchia]SL01
    |    |  i. s.: Brachychampsa Gilmore 1911D07
    |    |           |--B. montanaSF03
    |    |           `--B. sealeyiD07
    |    |--+--Zaraasuchus shepardiGPS06
    |    |  `--Gobiosuchus [Gobiosuchidae]GPS06
    |    |       `--G. kielanaeGPS06
    |    `--+--+--Zosuchus davidsoniGPS06
    |       |  `--+--Shantungosuchus hangjinensisGPS06
    |       |     `--Sichuanosuchus shuhanensisGPS06
    |       `--+--MetasuchiaGPS06
    |          `--HsisosuchidaeB93
    |               |--Hsisosuchus chungkingensis Young & Chow 1953GPS06, B93
    |               `--Doratodon carcharidens (Bunzel 1871)B93
         |--Orthosuchus [Orthosuchidae]GPS06
         |    `--O. stormbergi Nash 1968B93
         `--Protosuchidae [Stegomosuchidae]GPS06
              |  i. s.: NotochampsaR72
              |         ErythrochampsaR72
              |         Stegomosuchus longipes Lull 1953B93
              |         PlatyognathusR72
              |         MicrochampsaR72
              |         Dyoplax arenaceus Fraas 1867B93
              |--Edentosuchus tienshanensis Young 1973GPS06, B93
              `--+--Hemiprotosuchus leali Bonaparte 1969GPS06, B93
                 `--Protosuchus Brown 1934GPS06, D07 (see below for synonymy)
                      |--P. haughtoniD07
                      |--P. micmacD07
                      `--P. richardsoniGPS06
Crocodyliformes incertae sedis:
    |--D. sphenops Cope 1875C77
    `--D. subulatusC77
  Allodaposuchus precedens Nopcsa 1928PST99
  Aigialosuchus Persson 1959LS04
    |--A. depressifronsRRO00
    `--A. nanlingensis Young 1964SM71
  Eoalligator chunyii Young 1964SM71
  Eotomistoma multidentata Young 1964 [=Eotomiostoma (l. c.) multidentata]SM71

Protosuchus Brown 1934GPS06, D07 [incl. ArchaeosuchusR72, Baroqueosuchus Busbey & Gow 1984BC88, Lesothosuchus Whetstone & Whybrow 1983BC88]

*Type species of generic name indicated


[B93] Benton, M. J. 1993. Reptilia. In: Benton, M. J. (ed.) The Fossil Record 2 pp. 681–715. Chapman & Hall: London.

[BC88] Benton, M. J., & J. M. Clark. 1988. Archosaur phylogeny and the relationships of the Crocodylia. In: Benton, M. J. (ed.) The Phylogeny and Classification of the Tetrapods vol. 1. Amphibians, Reptiles, Birds pp. 295–338. Clarendon Press: Oxford.

[C77] Cope, E. D. 1877. Report upon the extinct Vertebrata obtained in New Mexico by parties of the expedition of 1874. Geographical Surveys West of the One Hundredth Meridian 4 (2): i–iv, 1–370.

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

[GPS06] Gasparini, Z., D. Pol & L. A. Spalletti. 2006. An unusual marine crocodyliform from the Jurassic–Cretaceous boundary of Patagonia. Science 311: 70–73.

[LS04] Lindgren, J., & M. Siverson. 2004. The first record of the mosasaur Clidastes from Europe and its palaeogeographical implications. Acta Palaeontologica Polonica 49 (2): 219–234.

[PST99] Pereda Suberbiola, X., & P. Taquet. 1999. Restes de Rhabdodon (dinosaure ornithopode) de Transylvanie donnés par Nopcsa au Muséum national d’Histoire naturelle de Paris. Geodiversitas 21 (2): 157–166.

[R72] Romer, A. S. 1972. The Chañares (Argentina) Triassic reptile fauna. XVI. Thecodont classification. Breviora 395: 1–24.

[RRO00] Rossmann, T., M. Rauhe & F. Ortega. 2000. Studies on Cenozoic crocodiles: 8. Bergisuchus dietrichbergi Kuhn (Sebecosuchia: Bergisuchidae n. fam.) from the Middle Eocene of Germany, some new systematic and biological conclusions. Paläontologische Zeitschrift 74: 379–392.

[SF03] Salisbury, S. W., E. Frey, D. M. Martill & M. C. Buchy. 2003. A new crocodilian from the Lower Cretaceous Crato Formatioin of north-eastern Brazil. Palaeontographica Abteilung A: Paläozoologie—Stratigraphie 270: 3–47.

[SL01] Sereno, P. C., H. C. E. Larsson, C. A. Sidor & B. Gado. 2001. The giant crocodyliform Sarcosuchus from the Cretaceous of Africa. Science 294: 1516–1519.

[SM71] Szalay, F. S., & M. C. McKenna. 1971. Beginning of the age of mammals in Asia: the late Paleocene Gashato fauna, Mongolia. Bulletin of the American Museum of Natural History 144 (4): 269–318.

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