Morphometric analysis in embryos of black yacare Caiman yacare (Crocodylia, Alligatoridae).

JOAQUIN, LEILA; CABRERA, MARIO R.; PRADO, WALTER

Santa Cruz de la Sierra

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

IUCN - The World Conservation Union

In embryology it is useful to establish a descriptive system of classification of stages of the embrionary development that serves to correlate their different phases in a temporary scale, under specific conditions of incubation. At the same time, it is useful evaluate the existence of biometric relationships that, together with the system of stages, could serve to develop a tool to estimate the exact moment of the oviposition. The objective of this work is to formulate a basic method to taking morphological data and to analyze the growth patterns. For it, 33 embryos field-collected in the Argentinean province of El Chaco (26° 43´ 39.1´´ S; 59° 03´ 27.4´´ W) were used. Each embryo stage was determined under a dissecting microscope; 18 measures were taken with a digital caliper (± 0.01 mm), and a guide-instructive with photographs was designed to aid in the measurement of the structures. The Statgraphics Centurion XV software was used to describe the  growth patterns, correlating the morphometrics obtained to the different stages. The model that better adjusts to the growth of the different structures in Caiman yacare embryos correspond to second order curves: Y = ax + bx2,  where ?Y? is the morphometric measured and ?x? is the stage.