Osteomorphological Features of the Carcass of Inia geoffrensis (Cetacea: Iniidae)

Abstract

Osteological studies can have implications that allow direct biological inferences to be made, such as locomotion, as well as indirect ones, such as species distribution, evolution and ecology. This study was aimed at describing some osteological traits of Inia geoffrensis (Blainvillei, 1817), Macapá/AP. A nearly complete carcass was found in a local forest. Information about the killing was collected through community reports. After collecting bones and information, the carcass was taken to the Laboratory of Zoology at the Federal University of Amapá for cleaning and examination. The cleaning process was carried out following the step-by-step maceration protocol and measurements of bones were taken with a measuring tape (2 m) and ruler (50 cm), except for cervical vertebrae, which were measured with a caliper (15 cm). To find the limbs in the carcass, an identification guide and a bone chart of aquatic mammals were used. Based on the observed data, the animal was a female, determined by the genital cleft. Examination of the occipital bone revealed an adult with complete bone fusion, obliterated sutures on the external surface of the skull. The carcass was nearly complete, with the entire face measuring 55 cm. Further studies are needed on environmental education about cetaceans, local awareness with the assistance of inspectors and competent authorities for the conservation of freshwater dolphins in the region and studies on carcasses for the maintenance of the species.