Intraspecific postcranial histovariability of the broad-snouted caiman Caiman latirostris Daudin, 1802

MARÍA EUGENIA PEREYRA; BONA, PAULA; ANUSUYA CHINSAMY; PABLO SIROSKI

Drakensberg

Congreso; 2023 Conference of the Zoological Society of Southern Africa; 2023

Crocodylia is a clade of neosuquian Crocodyliforms today represented by over twenty species with generally medium body sizes. Modern crocodilians exhibit important physiological plasticity linked to environmental conditions, habitat, feeding, sex, and other intra-population factors. Bone tissue is an important structural component of the skeleton of vertebrates and is involved in the physiology of these animals throughout their development. Thus, a study of the osteohistology provides a reliable source of information to deduce biological information, such as longevity, growth dynamics, body size, metabolism, and sexual and somatic maturation. Although osteohistology studies in Neosuchia are relatively numerous, the diversity of species studied is still lacking. Here, we fill this gap by examining the ontogenetic postcranial histology of the modern South American caiman, Caiman latirostris. Our study sample consisted of 12 different sized individuals, from which we prepared calcified transverse thin sections of the forelimb and hindlimb bones of each individual. Our results show ontogenetic variation in the type of bone tissues deposited throughout development, and using the growth marks preserved in the compacta we were able to develop growth curves of these individuals. Furthermore, although some sections revealed the classical lamellar, parallel-fibered, or woven bone matrices, others showed unusual bone tissues. Older specimens exhibited a decrease in bone depositional rates that are evident on the basis of the organization of the collagen fibers and the scarce vascularization. The differences in the bone histology are likely related to plasticity and variability in the growth dynamics of caimans and offer a wide theoretical framework for life history interpretations for this group.