Phylogenetic Systematics of I guanine Lizards 1 9 



meaningful way. Similarly, the use of standard endings for new taxa proposed in this 

 study is an attempt to conform with nomenclatural rules rather than to designate categorical 

 ranks. Although these practices go against tradition, they convey the current state of 

 knowledge precisely. If taxonomies are to serve as summaries of phylogenetic knowledge, 

 conveying such information is more valuable than being able to pigeonhole all organisms 

 equally. 



Iguaninae Bell 1 825 



Diagnosis. The following combination of characters is diagnostic for iguanines, 

 separating the members of this group not only from all other iguanids but also from all 

 other iguanians and probably from all other squamates: 



1. some caudal vertebrae with two pairs of transverse processes that diverge from one 

 another (Etheridge, 1967); 



2. the presence of transverse valves or folds in the colon (Iverson, 1980, 1982); 



3. crowns of posterior marginal teeth laterally compressed, anteroposteriorly flared, 

 and often polycuspate (Etheridge, 1964a); 



4. the supratemporal lies primarily on the posteromedial surface of the supratemporal 

 process of the parietal; 



5. primarily herbivorous diet (H. M. Smith, 1946). 



This list does not include all features in which iguanines exhibit a derived condition 

 within Iguanidae; it consists of only those that I consider to be true iguanine 

 synapomorphies evidencing monophyly of the group. The first two are unique to 

 iguanines (within iguanids) and are therefore unproblematic. Each can be used alone to 

 distinguish an iguanine from any other iguanid, though colic anatomy is unknown for 

 many members of the family. The other characters occur in some noniguanine iguanids 

 where I consider them to be convergent, a conclusion necessitated by conflicting 

 distributions of other derived characters. Still other apomorphic characters of iguanines are 

 not included in the diagnosis. These characters are also more widely distributed and may 

 be iguanine synapomorphies (in which case, other convergences will be required) or may 

 serve to diagnose more inclusive clades within the Iguania. These characters are given in 

 the description. 



Description. The description below is a list of the apomorphies, plesiomorphies, and 

 characters of uncertain polarity shared by iguanines. In addition, some characters that vary 

 within the group are included. This list is meant to provide a basis for comparison with 

 other iguanids and is intended to be a source of characters that may be useful for examining 

 the relationships of iguanines to the rest of Iguanidae (and Iguania). For this reason, I 

 include only characters that vary within Iguanidae. Morphologies thought to be derived 

 within Iguanidae are indicated by an asterisk (*). 



HEAD SKELETON: premaxillary spine exposed dorsally or covered* between nasals; 

 surface of dermatocranium smooth or with irregular rugosities; parietal roof trapezoidal, V- 



