Body location and tail regeneration effects on osteoderms morphology-are they useful tools for systematic, paleontology, and skeletochronology in diploglossine lizards (squamata, anguidae)?

Although diploglossine osteoderms were mentioned in several systematic and paleontological studies, their morphological variability in single specimens or within species remains paradoxically undescribed. This is mainly the effect of the lack of attention paid hitherto to the morphological and histological characteristics of the tail osteoderms. This study demonstrated that a previously undescribed morphological variability exists in these osteoderms, especially in those resulting from tail regeneration. Indeed, regenerated osteoderms display a plesiomorphic anguid morphology that was previously considered to be absent in Diploglossinae. We also provide the first histological description of diploglossine osteoderms and new information about the obvious differences in growth dynamic between regenerated and nonregenerated osteoderms. These new data raise questions about the usefulness of diploglossine osteoderms in systematic, paleontological, and skeletochronological studies. Our study shows that the exact position on the trunk or on a regenerated or nonregenerated tail of each studied osteoderm must be known in order to avoid mistakes related to their important interspecies and intraspecies variability.