Bone histovariability of freshwater and terrestrial turtles: potential new Information for palaeohistology and palaeobiological interpretations

MARÍA EUGENIA PEREYRA; BONA, PAULA

Simposio; International Symposium on Palaeohistology; 2022

The bone microstructure is a reliable source of information to infer vertebrates ́ biology sincebone tissue revealed aspects related to their growth rates, longevity, life history, sexual andsomatic maturation, among others. The osteohistology of extant vertebrates provides essentialinformation to support palaeobiological hypotheses based on palaeohistology. Although thereare contributions focused on bone histology of extant and extinct turtles, there are still few taxaanalyzed. Also, it is interesting to notice that most osteohistology works are commonly focusedon turtles ́ shells; however, in the last years, long bones histology has regained importance.This work aims to identify osteohistological features of postcranial bones of freshwater andterrestrial species of Argentinian turtles and determine the degree of variation at intraskeletal,ontogenetic and interspecific levels. We perform thin sections of axial (vertebrae) andappendicular (girdle, stylopodium and zeugopodium) bones of juvenile and adult specimens ofPhrynops hilarii, Hydromedusa tectifera and Chelonoidis chilensis, belonging to theherpetological collection of the Museo de La Plata, Argentina. The cortical bone is mostlyformed by lamellar and parallel-fibered bone. Vascular canals are scarce and mostlylongitudinally oriented. The bone histology reflects a slow growth rate and a limited variationat intraskeletal, ontogenetic and interspecific levels. Stylopodial, zeugopodial and somepectoral and pelvic girdle bones exhibit the best growth records, making these bones the bestelements for aging. The results obtained here expand the theoretical framework forpalaeohistological and palaeobiological interpretations on fossil turtles.