Interspecific patterns of variation in dental growth increments of crocodilians

BACKGROUND: Multiple studies have supported the hypothesis that incremental growth lines in crocodilian dentin are analogous with circadian von Ebner's lines in mammals; however, variation in these growth lines has been largely unstudied. It is also unknown whether accentuated dentin striations in crocodilians may represent a supradian periodicity analogous to Andresen lines in mammalian dentin. Therefore, the objective of this study is to histologically assess variation in von Ebner's lines and accentuated growth lines among crocodilians. RESULTS: The data do not support the hypothesis that crocodilians express supradian periodicity in accentuated striations of dentin. DSR is significantly correlated with total length and body mass. DSR variance also shows a significant relationship with body size. CONCLUSIONS: Body size seems to be the major factor governing DSR in crocodilians; this relationship is expressed both intra- and interspecifically in this dataset, warranting further study of intraspecific variation to assess the impact of ontogeny on DSR within this group. Accentuated striations may not be useful as markers of periodicity in crocodilians, but may be useful indicators of stress or other physiological events in life history analyses.