Fig. 1.

Dinosaurian relationships, showing major clades discussed in the text and the phylogenetic position of Lesothosaurus diagnosticus. Although Lesothosaurus has been recovered in a number of different positions in recent cladistic analyses (Sereno, 1999; Butler et al. 2008, 2010), this is to be expected from a taxon that displays few autapomorphies but shares numerous features with basal members of all ornithischian lineages, representing the ‘ancestral’ condition. We follow Sereno (1999) herein, in line with Maidment & Barrett (2011). a, avian pelvis in right lateral view; b, basal ornithischian pelvis in right lateral view; both after Maidment & Barrett (2011) and not to scale. 1, elongate preacetabular process of the ilium; 2, retroversion of the pubis; 3, habitual quadrupedal stance.