Détermination Squelettochronologique de l'Ăge dans une Population de Cophosaurus texanus (Sauria, Iguanidae)

Abstract The age of 103 specimens from a wild population of Cophosaurus texanus (Sauria, Iguanidae) from Mexico is determined by counting skeletal growth rings in the diaphysis of the humerus and phalanges. The skeletochronological analysis of 8 lizards ofknown age supports the practical value of the method. However, inacuracies do occur in practice for age assessement of a few specimens. I n the sample studied, we observed three main age groups (and possibly a fourth one based on a single specimen four years old). The one year age class is the most numerous, accounting for 75 % of the sample studied. Females lay eggs twice each summer with an interval of sixty days between each spawning. The use ofthe skeletochronological method also allows to sort out the individuals belonging to the first or to the second clutch, at every stage of their subsequent lives.