Crurotarsi

From Palaeos

o Sauria
|--Lepidosauromorpha
`--o Archosauromorpha
   |?--Choristodera
   `--+--Rhynchosauria
      `--+--Trilophosauridae
         `--+--Prolacertiformes
            `--o--Proterosuchidae 
               `--+--Erythrosuchidae
                  `--+--Euparkeriidae
                     `--o--Proterochampsidae
                        `--o Archosauria
                           |--o Ornithodira
                           |  |--Pterosauria
                           |  `--Dinosauromorpha
                           `--Crurotarsi

[edit] Introduction

The Crurotarsi ("cross-ankles") are a group of archosaurs created as a node-based clade by Paul Sereno in 1991 to supplant the old term Pseudosuchia. Sereno accidentally did not create a stem clade as had been his intention as the basal phylogeny of this clade is not really understood. In 2005 a stem-based exact definition was given by Sereno: all forms closer to Crocodylus niloticus than to Passer domesticus (thus to Crocodiles rather than to Birds). As such, the Crurotarsi are by definition the sister group of the Ornithodira (all forms closer to Birds than Crocodiles). In terms of the old Linnean taxonomy they correspond more or less to the Orders Thecodonta (minus the Proterosuchia) and Crocodylia

The Crurotarsi are one of the two primary daughter clades of the Archosauria. The skull is often massively built, especially in contrast to ornithodires; the snout narrow and sometimes tending to be elongate, the neck is short and strong, and the limb posture ranging from typically reptilian sprawling to dinosaur or mammal-like erect (although this is achieved in a different way to dinosaurs and mammals). The body is often protected by two or more rows of armoured plates. Many forms reached large size; 3 meters or more in length.

Crurotarsans seem to have appeared during the late Olenekian (early Triassic); by the Ladinian (late Middle Triassic) they dominated the terrestrial carnivore niches. Their heyday was the Late Triassic, during which time their ranks included erect-limbed rauisuchians, the crocodile-like phytosaurs, herbivorous armoured aetosaurs, the large predatory poposaurs, the small agile protocrocodilian Sphenosuchia, and a few other assorted groups.

At the end Triassic extinction, all of the large crurotarsans died out, allowing the dinosaurs to succeed them as rulers of the land. Only the little Sphenosuchia and the Protosuchia (Crocodylia) survived.

As the Mesozoic proceeded, the Protosuchia gave rise to more typically crocodile like forms (the Crocodylia proper), and, while Dinosaurs were the dominant animals on land, the crocodiles flourished in rivers, swamps, and the ocean; with far greater diversity than they have today.

With the end Cretaceous extinction the tables were turned - the ornithodiran dinosaurs died out except for the birds while the curotarsan crocodylians continued with little change.

Today, the crocodiles, alligators, and gavials continue as the surviving representatives of this ancient and successful lineage.

o Archosauria 
|--Ornithodira
`--o CRUROTARSI
   |--Phytosauridae
   `--o--o?--Ornithosuchidae 
      |  `--+?--Prestosuchidae (grade?)
      |     `--+--Rauisuchidae
      |        `--+?--Ctenosauriscidae
      |           `?--Poposauridae
      `--o--Stagonolepididae
         `--+--Euscolosuchus  
            `--o--Gracilisuchus stipanicicorum
                |?--Poposauridae
                `--o--Erpetosuchus granti
                   `--Crocodylomorpha

[edit] Phylogenetic Trees

The following trees are from Mikko's Phylogeny Archive. A number of problematic taxa have been excluded.

[edit] After Parrish, 1993

<==o Crurotarsi Sereno & Arcucci, 1990 sensu Parrish, 1993
   `--o Crocodylotarsi Gauthier & Padian, 1985
      |--o †Ornithosuchidae
      |  |?- †Venaticosuchus rusconii
      |  |-- †Riojasuchus tenuisceps
      |  `--o †Ornithosuchus
      |     |-- †O. rusconii
      |     `-- †O. longidens
      `--+-- †Phytosauria Meyer, 1861 [Parasuchia Huxley, 1875]
         `--o Suchia Krebs, 1976 [1974?] sensu Parrish, 1993 (advanced crurotarsans, incl. crocodiles)
            |--o †Prestosuchidae Romer, 1966 sensu Parrish, 1993
            |  |-- †Ticinosuchus ferox Krebs, 1965 [“Mandasuchus” Charig, 1957]
            |  `--+-- †Saurosuchus galilei Reig, 1959
            |     |-- †Batrachotomus kupferzellensis Gower, 1999 [transferred to Rauisuchidae?]
            |     `--o †Prestosuchus Huene, 1942
            |        |-- †P. chiniquensis Huene, 1942
            |        `?- †P. loricatus Huene, 1942 [cospecific with P. chiniquensis sensu Parrish, 1993]
            `--+?- †Lewisuchus admixtus Romer, 1972 [possibly a dinosauromorph?! (Paul, 1988)]
               |?-o †Turfanosuchus Young, 1973 [however, see Archosauriformes for alternative position after Wu & Russell, 2001]
               |  |-- †T. shageduensis Wu, 1982 [or 1986]
               |  `-- †T. dabanensis Young, 1973
               `--o Rauisuchiformes Huene, 1942 sensu Parrish, 1993
                  |--+?- †Revueltosaurus callenderi Hunt, 1989
                  |  `-- †Aetosauria Lydekker, 1889 [Aëtosauria] (aetosaurs)
                  `--o Rauisuchia Huene, 1942 [non Bonaparte, 1982] sensu Parrish, 1993
                     |-- †Rauisuchidae Huene, 1942 (rauisuchids)
                     `--o Paracrocodylomorpha Parrish, 1993
                        |-- †Gracilisuchus stipanicicorum Romer, 1972a
                        `--+-- †Poposauridae Nopsca, 1928 [1923] [incl. Chatterjeeidae Long & Murry, 1995]
                           `--o Bathyotica Benton & Walker, 2002
                              |-- †Erpetosuchus granti Newton, 1894 [Erpetosuchidae Watson, 1917] [incl. Parringtonia gracilis??]
                              `-- Crocodylomorpha Walker, 1968 (crocodile-like archosaurs)

[edit] After Parrish, 1993, Nesbitt, 2003, 2005, and Nesbitt & Norell, 2006

<==o Suchia Krebs, 1976 [1974?] sensu Parrish, 1993
   |--o †Prestosuchidae Romer, 1966 sensu Parrish, 1993
   |  |-- †Ticinosuchus ferox Krebs, 1965 [“Mandasuchus” Charig, in Krebs, 1957 (nomen nudum)]
   |  `--+-- †Saurosuchus galilei Reig, 1959
   |     |-- †Batrachotomus kupferzellensis Gower, 1999 [transferred to Rauisuchidae?]
   |     `--o †Prestosuchus Huene, 1942
   |        `-- †P. chiniquensis Huene, 1942
   `--+?- †Lewisuchus admixtus Romer, 1972 [possibly a dinosauromorph?! (Paul, 1988)]
      |?-o †Turfanosuchus Young, 1973 [however, see Archosauriformes for alternative position after Wu & Russell, 2001]
      |  |-- †T. shageduensis Wu, 1982 [or 1986]
      |  `-- †T. dabanensis Young, 1973
      `--o Rauisuchiformes Huene, 1942 sensu Parrish, 1993
         |--+?- †Revueltosaurus callenderi Hunt, 1989 [?incl. †Krzyzanowskisaurus hunti (Heckert, 2002) Heckert, 2005 (tooth-taxa)]
         |  `-- †Aetosauria Lydekker, 1889 [Aëtosauria] (kärsäkrokotiilit; aetosaurs)
         `--o Rauisuchia Huene, 1942 [non Bonaparte, 1982] sensu Parrish, 1993
            |-- †Rauisuchidae Huene, 1942 (rauisuchids)
            `--o Paracrocodylomorpha Parrish, 1993
               |-- †Gracilisuchus stipanicicorum Romer, 1972a
               `--+--o Bathyotica Benton & Walker, 2002
                  |  |-- †Erpetosuchus granti Newton, 1894 [Erpetosuchidae Watson, 1917] [incl. Parringtonia gracilis??]
                  |  `-- Crocodylomorpha Walker, 1968 (krokotiilimaiset arkosaurit; crocodile-like archosaurs)
                  `--o †Poposauria
                     |--o †Ctenosauriscidae Kuhn, 1964 [Ctenosauridae Kuhn, 1961] [incl. †Lotosauridae Zhang, 1975; †Shuvosauridae Chatterjee, 1993; †Chatterjeeidae Long & Murry, 1995]
                     |  |-- †Ctenosauriscus koeneni (v. Huene) Kuhn 1964 [Ctenosaurus von Huene, 1902 (non Ctenosaurus Fitzinger, 1843)]
                     |  |-- †Bromsgroveia walkeri Galton, 1985
                     |  |-- †Arizonasaurus babbitti Welles, 1947; M.Trias. SWNA.
                     |  |-- †Lotosaurus edentus Zhang, 1975; U.Trias. EAs.
                     |  `--+?- †Sillosuchus longicervix Alcober & Parrish, 1997
                     |     |-- †Shuvosaurus inexpectatus Chatterjee, 1993 [incl. †Chatterjeea elegans Long & Murry, 1995 (Mueller, 2003, and Nesbitt & Norell, 2006)] U.Trias. SWNA.
                     |     `-- †Effigia okeeffeae Nesbitt & Norell, 2006; U.Trias. SWNA.
                     `--o †Poposauridae Nopsca, 1928 [1923]
                        |-- †Poposaurus gracilis Mehl, 1915 (non? Nopsca, 1921)
                        `-- †Lythrosuchus langstoni Long & Murry, 1995 [Lythrosaurus (lapsus calami)] [cogeneric with Poposaurus?? (Mueller, 2003)]

[edit] After Gower, 2002

<==o Suchia Krebs, 1976 [1974?] sensu Parrish, 1993
   |-- †Saurosuchus galilei Reig, 1959
   `--+-- †Batrachotomus kupferzellensis Gower, 2000?
      |--o †Prestosuchidae Romer, 1966 sensu Parrish, 1993
      |  |?- †Ticinosuchus ferox Krebs, 1965 ["Mandasuchus" Charig, 1957]
      |  |-- †Tikisaurus romeri Chatterjee & Majumdar, 1987
      |  `--o †Prestosuchus Huene, 1942
      |     |-- †P. chiniquensis Huene, 1942
      |     `?- †P. loricatus Huene, 1942 [cospecific with P. chiniquensis sensu Parrish, 1993]
      |?- †Rauisuchidae Huene, 1942 (karhukrokotiilit; rauisuchids)
      |??- †Lewisuchus admixtus Romer, 1972 [possibly a dinosauromorph?! (Paul, 1988)]
      |?-o †Turfanosuchus Young, 1973 [however, see Archosauriformes for alternative position after Wu & Russell, 2001]
      |  |-- †T. shageduensis Wu, 1982 [or 1986]
      |  `-- †T. dabanensis Young, 1973
      `--+-- †Aetosauria Lydekker, 1889 [Aëtosauria] (aetosaurs)
         `--o Paracrocodylomorpha Parrish, 1993
            |-- †Gracilisuchus stipanicicorum Romer, 1972a
           `--+-- †Poposauridae Nopsca, 1928 [1923] [incl. Chatterjeeidae Long & Murry, 1995]
              `--o Bathyotica Benton & Walker, 2002
                 |-- †Erpetosuchus granti Newton, 1894 [Erpetosuchidae Watson, 1917] [incl. Parringtonia gracilis??]
                 `-- Crocodylomorpha Walker, 1968 (crocodile-like archosaurs)

[edit] References

• Arcucci, A. B. & Marsicano, C. A., 1998: A distictive new archosaur from the Middle Triassic (Los Chañares Formation) of Argentina. Journal of Vertebrate Paleontology: Vol. 18, #1, pp. 228-232
• Benton, M. J. & Walker, A. D., 2002: Erpetosuchus, a crocodile-like basal archosaur from the Late Triassic of Elgin, Scotland. Zoological Journal of the Linnean Society: Vol. 136, #1, pp. 25-47
• Carroll, R. L., 1988: Vertebrate paleontology and evolution. –W. H. Freeman and company, New York, 1988, 698
• Creisler, B. (& Poling, J.,) 2003: Rauisuchia Translation and Pronunciation guide. (Updated: 2003-07-07)
• Doyle, K. D. & Sues, H.-D., 1995: Phytosaurs (Reptilia: Archosauria) from the Upper Triassic New Oxford Formation of York County, Pennsylvania. Journal of Vertebrate Paleontology: Vol. 15, #3, pp. 545-553
• iNet: Dinosauria.com: http://www.dinosauria.com/dml/names/rau.htm; [visited: 2006-01-27]
• Gower, D. J., 2002: Braincase evolution in suchian archosaurs (Reptilia: Diapsida): evidence from the rauisuchian Batrachotomus kupferzellensis. Zoological Journal of the Linnean Society: Vol. 136, #1, pp. 49-76
• Hunt, A. P., Lucas, S. G. & Spielmann, J. A., 2005: The postcranial skeleton of Revueltosaurus callenderi (Archosauria: Crurotarsi) from the Upper Triassic of Arizona and New Mexico, USA. pp. 67-75

in Heckert, A. B. & Lucas, S. G., (eds.) 2005: Vertebrate Paleontology in Arizona. New Mexico Museum of Natural History and Science Bulletin: #29 [from abstract]

• Luo, Z, & Wu, X-C., 1994: The small tetrapods of the Lower Lufeng Formation, Yunnan, China. 251-270 in Fraser, N. C. & Sues, H-D. (eds.) 1994: In the Shadow of the Dinosaurs. Cambridge University Press, New York. 1994. x-435
• Mueller, B., 2003: Personal correspondence (MH)
• Nesbitt, S. J., 2003: Arizonasaurus and its implications for archosaur divergence. Proceedings of the Royal Society of London: Biological series: Vol. 270 (Supplement 2), pp. S234-S237
• Nesbitt, S. J., 2005: Osteology of the Middle Triassic pseudosuchian archosaur Arizonasaurus babbitti. Historical Biology: Vol. 17, #1-4, pp. 19-47
• Nesbitt, S. J. & Norell, M. A., 2006: Extreme convergence in the body plans of an early suchian (Archosauria) and ornithomimid dinosaurs (Theropoda). Proceedings of the Royal Society of London: Biological series: Advanced online publication, pp. 1-4
• Olsen, P. E., Sues, H.-D. & Norell, M. A., 2000: First record of Erpetosuchus (Reptilia: Archosauria) from the Late Triassic of North America. Journal of Vertebrate Paleontology: Vol. 20, #4, pp. 633-636
• Parrish, J. M. 1993: Phylogeny of the Crocodylotarsi, with Reference to Archosaurian and Crurotarsan Monophyly. Journal of Vertebrate Paleontology: vol. 13, #3, pp. 287-308
• Parker, W. G., Irmis, R. B., Nesbitt, S. J., Martz, J. W. & Browne, L. S., 2005: The Late Triassic pseudosuchian Revueltosaurus callenderi and its implications for the diversity of early ornithischian dinosaurs. Proceedings of the Royal Society of London: Biological series: Vol. 272, pp. 963-969
• Sereno, P. C. 1991: Basal Archosaurs: phylogenetic relationships and functional implications. Journal of Vertebrate Paleontology: Vol. 11, Supplement to #4, Memoir 2. pp. ii-53
• Sues, H.-D., 1992: A remarkable new armored archosaur from the Upper Triassic of Virginia. Journal of Vertebrate Paleontology: vol. 12, #2, pp. 142-149
• Sues, H.-D., Olsen, P. E. & Kroehler, P. A., 1994: Small tetrapods from the Upper Triassic of the Richmond basin (Newark Supergroup), Virginia. 161-170 in Fraser, N. C. & Sues, H-D. (eds.) 1994: In the Shadow of the Dinosaurs. Cambridge University Press, New York. 1994. x-435

[edit] Credits

Introduction MAK050225 Wikipedia (current page), Phylpogeny © Mikko Haaramo 2003, 2005