Verification of the skeletochronology technique in the Broad-snouted caiman, Caiman latirostris (Reptilia, Alligatoridae).

AYARRAGARAY, MATIAS; MANZANO, ADRIANA; CABRERA, MARIO R.

Santa Cruz de la Sierra, Bolivia

Workshop; 19th Working Meeting of the Crocodile Specialist Group, IUCN; 2008

IUCN - The World Conservation Union

Skeletochronology is the name of a technique used to estimate the age in different extant and living vertebrates based on counting bone growth rings that are expression of histological change in the rates of osteogenesis influenced by external factors. Bone diameter growths by deposition of successive layers of new bone from the center to the external border, usually named as bone marks, that in histological cross sections look like rings. This technique has been succesfully applied on fishes, mphibians, and reptiles. In crocodiles, the information about the applicability of this technique is scarce, and particularly in caimans nothing is known. To determine the actual age through this method, two main objectives must be achieved: the observation of bone cross sections in order to investigate the cyclic growth represented by bone marks, and to determine if  each growth mark corresponds exactly to one year old of the specimen. In this work, details of the technique and preliminary information are presented on the use of it in phalanxes of the South American broad-snouted caiman for the first time, showing that Caiman latirostris presents bone growth rings similar in structure to those observed in other reptiles and in amphibians.