Polonosuchus silesiacus ( Sulej, 2005 )

Nesbitt, Sterling J., 2011, The Early Evolution Of Archosaurs: Relationships And The Origin Of Major Clades, Bulletin of the American Museum of Natural History 2011 (352), pp. 1-292 : 37

Polonosuchus silesiacus ( Sulej, 2005) , sensu Brusatte et al., 2009 (fig. 11B)

AGE: Late Carnian ( Dzik and Sulej, 2007).

OCCURRENCE: Krasiejów, Opole, Silesia, Poland ( Sulej, 2005).

HOLOTYPE: ZPAL Ab III/563, right and left maxillae, premaxillae, nasals, prefrontals, palatines, quadrates, and fragments of dentary, left jugal, right lacrimal, quadratojugal, squamosal, pterygoid, surangular, articular, fragment of atlas articulated with axis and third cervical vertebra, 12 articulated caudal vertebrae, five caudal osteoderms, and pieces of cervical ribs.

REMARKS: Sulej (2005) first described ZPAL Ab III/563 and assigned it to a new species-level taxon in the genus Teratosaurus because of similarities with Teratosaurus suevicus (BMNH 38646). In a superficial discussion, Lucas et al. (2007a) rejected all differences between the two taxa of Teratosaurus and stated that ZPAL Ab III/563 was referable to Teratosaurus suevicus . However, Lucas et al. (2007a) did little to discuss the anatomy of either taxon. Brusatte et al. (2009) showed that there are no clear apomorphies to unite ZPAL Ab III/563 and Teratosaurus suevicus exclusive of closely related taxa (e.g., Postosuchus kirkpatricki ), found that ZPAL Ab III/563 and BMNH 38646 differed extensively, and, therefore, assigned ZPAL Ab III/563 to the new genus Polonosuchus . Polonosuchus was hypothesized to be closely related to Postosuchus kirkpatricki in phylogenetic analyses of basal archosaurs ( Weinbaum and Hungerbühler, 2007; Brusatte et al., 2009).

Polonosuchus silesiacus differs from Postosuchus kirkpatricki by: ventral margin of the maxilla sinuous and highly convex in outline; first maxillary alveolus approximately equal in size to subsequent alveoli; nasal with bifurcated anterior end, including tapering premaxillary process that contacts the premaxilla; maxillary process of premaxilla terminating anterior to the caudal end of the external naris; absence of fossa on the dorsal surface of the nasal; absence of dorsoventral expansion of the anterior end of the dentary (from Brusatte et al., 2009).

KEY REFERENCES: Sulej, 2005; Brusatte et al., 2009.