Type Species: Hesperosuchus agilis Colbert, 1952

Other Species: none

Systematic Paleontology:
Archosauria Cope, 1869
  Crocodylomorpha Hay, 1930 emend. Walker, 1968
    Sphenosuchidae Haughton, 1924
      Hesperosuchus Colbert, 1952

Note: Colbert (1952) originally assigned Hesperosuchus to the orntihosuchidae.

Type Specimen: Holotype - AMNH 6758, partial skeleton including fragmentary skull, vertebrae, ribs, dorsal scutes, girdle and limb bones.
Note: Holotype consists of two individuals (Bonaparte, 1972; Clark et al., 2000).

Figures: Colbert (1952: figs. 3, 5-12, 14-31, 33, pl. 49); Parrish (1991: figs. 3-9); Clark et al. (2000: figs. 1-3).

Type Locality: North side of Little Colorado River, near Tanner Crossing, about 6 miles SE of Cameron, Arizona, USA.

Type Horizon and Age: “lower Petrified Forest Member” (= upper Blue Mesa or lower Sonsela Member of Woody, 2003), late Carnian, Late Triassic.

Specimen history: Collected by Barnum Brown in 1929-1930.

Referred specimens: UCMP 129740, partial skeleton (Parrish, 1991) from the Dinosaur Hill Locality (PFV 040),(Upper) Petrified Forest Member, Petrified Forest National Park, AZ; CM 29894, skull and articulated partial postcranial skeleton (Clark et al., 2000) from the Whittaker Quarry, Rock Point Member, Chinle Formation, NM.
Note: Parrish (1991) originally referred UCMP 129740 to cf. Sphenosuchus sp., however, Sereno and Wild (1992), Long and Murry (1995), and Clark et al. (2000) have demonstrated that this specimen is referable to Hesperosuchus.

Diagnosis: (Clark et al., 2000) Dentary with deep symphyseal end. Other potentially diagnostic apomorphies include: single large palpebral bone in each orbit; supratemporal fossa extending laterally to lateral edge of squamosal; parietal crests on medial edges of supratemporal fossae separated by narrow median sulcus.

References:
Bonaparte, J. F., 1972. Los tetrápodos del sector superior de la Formacion Los Colorados, La Rioja, Argentina (Triásico Superior). 1 Parte. Opera Lilloana 22:1-183.

Clark, J. M., H- D., Sues, and D. S. Berman, 2000. A new specimen of Hesperosuchus agilis from the Upper Triassic of New Mexico and the interrelationships of basal crocodylomorph archosaurs. Journal of Vertebrate Paleontology 20(4):683-704.

Colbert, E. H., 1952. A pseudosuchian reptile from Arizona. Bulletin of the American Museum of Natural History 99(10):561-592.

Long, R. A., and P. A. Murry, 1995. Late Triassic (Carnian and Norian) tetrapods from the southwestern United States. New Mexico Museum of Natural History and Science Bulletin 4:1-254.

Parrish, J. M., 1991. A new specimen of an early crodylomorph (cf. Sphenosuchus sp.) from the Upper Triassic Chinle Formation of Petrified Forest National Park. Journal of Vertebrate Paleontology 11:198-212.

Sereno, P. C., and R. Wild, 1992. Procompsognathus: theropod, “thecodont” or both? Journal of Vertebrate Palentology 12:435-458.