ANALYSIS OF PHYLOGENETIC RELATIONSHIPS 



Following character analysis, the phylogenetic relationships among the eight iguanine 

 genera (basic taxa) and the diagnoses of various monophyletic groups of iguanines, 

 including the basic taxa, were determined by means of a three-step procedure: (1) First, the 

 derived characters shared by the members of two or more basic taxa were used for a 

 preliminary analysis of phylogenetic relationships. (2) Second, certain phylogenetic 

 relationships based on the preliminary analysis were used to identify new outgroups for the 

 determination of polarities of characters that were undeterminable using basiliscines, 

 crotaphytines, morunasaurs, and oplurines as outgroups. These characters were then 

 added to the existing set for a second analysis of relationships within a subgroup of 

 iguanines. (3) Third, the results of the two analyses were combined to produce a final 

 estimate of phylogenetic relationships within Iguaninae, and the level at which each 

 character exists as a synapomorphy was reanalyzed in light both of these relationships and 

 of variation within the basic taxa. 



PRELIMINARY ANALYSIS 



A total of 29 characters (numbers 5, 7, 8, 13, 17, 18, 19, 21, 23, 25, 28, 36, 37, 39, 40, 

 45, 46, 48, 50, 51, 52, 54, 62, 66, 68, 69, 70, 77, 83), representing a minimum of 30 

 phylogenetic transformations, were used in the preliminary analysis of relationships. 

 These are the characters whose derived states are shared by two or more basic taxa 

 (category III). Character 46 has multiple states, with two levels (states 1, 2, and 3; states 2 

 and 3) that are shared by two or more taxa. This accounts for the difference between the 

 number of characters and the minimum number of phylogenetic transformations. Table 7 

 gives the 29 characters rescored to eliminate variation within basic taxa, as described under 

 Materials and Methods, above. 



The results of the preliminary analysis are summarized in Figure 46. Two different 

 cladograms (Fig. 46A,B) can account for the distribution of derived characters with a 

 minimum number of phylogenetic character transformations. In terms of the phylogenetic 

 relationships suggested, the two cladograms differ only in the positions oi Brachylophiis 

 and Dipsosaiirus. In one (Fig. 46A), Dipsosaurus is the sister group of all other iguanines; 

 in the other (Fig. 46B), Brachylophiis occupies this position instead. 



The minimum-step cladograms require 46 phylogenetic character transformations 

 (consistency index = 0.65), 16 more than the absolute minimum of 30, which would only 

 obtain if all of the characters had mutually compatible distributions among the basic taxa. 



117 



