The characteristics and affinities of the Amphisbaenia



The amphisbaenians, to judge from the many changes of opinion regarding their appropriate position among the vertebrates, appear to have puzzled most students of herpetology. Re-evaluation suggests that a case may now be made for classifying the amphisbaenians as an order, separate from the lizards and snakes, but included with them in a superorder Squamata. Evidence for such a position may be derived from several dozen systems in which amphisbaenians differ from lizards, from snakes, or from both. Although individual character states are occasionally equivalent to those shown by one or another family of lizards, there is no “closest” family. This suggests that the Amphisbaenia probably diverged from the remainder of the Squamata before the diversification of all present families of lizards. Unfortunately many of the character states are still known from only a limited number of amphisbaenians and information for other groupings of squamates is similarly inadequate.