128 



University of California Publications in Zoology 



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FIG. 50. Consensus cladogram for the three cladograms illustrated in Figure 49. The consensus 

 cladogram is also a minimum-step cladogram in that it requires the same number of character 

 transformations as do the three fully resolved cladograms upon which it is based. Synapomorphies for the 

 numbered nodes and the basic taxa are given in the text. 



Eight of the eleven homoplastic characters can be interpreted in two different ways, 

 each involving the same number of phylogenetic transformations on the minimum- step 

 cladograms. The alternative interpretations of character 57 have already been discussed. 

 Its derived state is either convergent in Ctenosaura and Iguana, or it is a synapomorphy of a 

 monophyletic group composed of Ctenosaura, Iguana, and Cyclura that has subsequently 

 reversed in Cyclura. Characters 54, 65, 68, 69, 70, 71, and 84 are either convergent in 

 Amblyrhynchus and Sauromalus or they are synapomorphies of a monophyletic group 

 composed of Amblyrhynchus, Conolophus, and Sauromalus that have subsequently 

 reversed in Conolophus. 



Although all three of the subterminal nodes on the consensus cladogram (not including 

 node 1, which is a conclusion of a higher-level analysis) are supported by at least two 

 derived characters, every one is contradicted by some other characters. Node 2, suggesting 

 a sister-group relationship between Sauromalus and the Galapagos iguanas, is supported 

 by two characters: reduced labial exposure of the angular bone (37-B) and short second 

 ceratobranchials (52-53-A). Nevertheless, the possession of polycuspate or serrate 

 marginal tooth crowns (character 46-B or-C) suggests that Sauromalus is more closely 



