In this study, the age structures of the four populations of Roughtail Rock Agama, Stellagama stellio distributed in Turkey were determined and their long bone development was examined from a histological perspective. The ages of some 218individuals (32 juveniles, 86 male male, 100 female female) captured from the Mediterranean, Transitional Mediterranean, Aegean, and Central Anatolia Regions were computed with the method of skeletochronology, and the correlation between age and the SVL (the snout-vent length) was compared. The mean SVL was greater in males than in females, and this difference was found statistically significant in all populations except for the Central Anatolian population. The mean ages for male and female individuals were calculated as 3.44 +/- 1.26 and 3.18 +/- 1.18 years in the Mediterranean population, as 4.65 +/- 1.25 and 3.69 +/- 1.31 years in the Transitional Mediterranean population, as 4.05 +/- 1.32 and 3.36 +/- 1.46 years in the Aegean population, and as 4.20 +/- 1.87 and 3.60 +/- 2.01 years in the Central Anatolian population, respectively. The oldest individuals were encountered in the Central Anatolian populations, and the maximum age detected for both sexes was 7 years. It was determined that the age at maturity was 3 in all the populations under examination and that there was not any difference in age at maturity either among the populations or between sexes. There was a significant positive correlation between age and the SVL. The impacts of environmental factors on age structures were examined, and altitude, latitude and climate were found effective on longevity. Histologically, the primary bone, which developed in the embryonic period, was preserved throughout the life of a species even in the oldest individual. Neither secondary bone development nor formation of lamellar systems was encountered. It was seen that intramembranous and endochondral ossification mechanisms played a joint role in long bone development.