[The use of cladistic principles in the phylogeny and biogeography of the Lacerta]

The methodology used in Phylogenetics remains one of the more interesting problems in comparative biology. Among the methods used, the cladistic is the most accurate. In the present case, among the Saurians, the characters chosen appeared early and cannot be referred to any adaptation bound to an evolutive progress. We have successively considered their distribution in the classification, their polarity and one phylogenetic hypothesis based on the Hennig's concepts. Such a work leads necessarily to systematical conclusions. For instance, we note the heterogeneity of some families. Among the Iguania, the Iguanidea are polyphyletics, the north-american forms breaking up from the other very early. Among the Scincomorpha, the Lacertilia result from two parts of different origins. This research verifies some systematic cuttings in the modern classification: among the Anguimorpha, the separation between Helodermatidea and the group, Varanidea-Lanthanotidea. The characters studied show a non-random distribution in the classification and show also some consistency with the geographical distribution of the extant Saurians. Therefore, it is important to search for the most parsimonious geographical hypothesis, which is in concern with the present data on the continental drift and generally on the history of the Earth, and which strengthens the cladograms posed from the selected characters.