“…ontogenetic variation, sexually dimorphic variation, polymorphisms) is crucial for accurate systematic, taxonomic, evolutionary, ecological, physiological and functional hypothesis of the different groups (Sudhaus and Rehfeld 1992;Wiesem€ uller et al 2003;Carpenter 2010;Porro et al 2011). Among extant crocodylians, previous studies of skull anatomy and intraspecific variation (including ontogenetic variation), evolution and functional morphology include those of Mook (1921), K€ alin (1933), Medem (1963), Iordansky (1973), Dodson (1975), Busbey (1989), Hall and Portier (1994), Monteiro and Soares (1997), Brochu (1999Brochu ( , 2001, Verdade (2000), Erickson et al (2003Erickson et al ( , 2012, McHenry et al (2006), Piña et al (2007), Wu et al (2006), Sadleir and Makovicky (2008), Platt et al (2009) and Bona and Desojo (2011). Nevertheless, lack of morphological studies and data, especially for osteology, is common to all extant South American crocodylians.…”