The abdominal skeleton of lizards in the family Iguanidae

Abstract

In certain iguanid lizards the costal cartilages of the abdomen form continuous chevron-shaped arcs posterior to the xiphisternum. In their characterizations of iguanid genera Boulenger (1885) and Cope (1886, 1892, 1900) used the term to refer to these continuous chevrons; lizards in which the costal cartilage pairs fail to meet one another midventrally were said to lack ribs. Variation in the abdominal skeleton of iguanid lizards is somewhat more complicated than the simple dichotomy 'abdominal ribs present or absent would indicate. The postxiphisternal cartilages exhibit four distinct patterns of attachment to the bony dorsal ribs, and for the most part the pattern of attachments is constant within genera and generic groups. It is the purpose of this work to describe the patterns of postxiphisternal costal cartilage attachments in the family Iguanidae, and to indicate some of the ways in which these patterns may be taxonomically useful.