Morphologic and morphometric characterization of skull of the gray dolphin, Sotalia fluviatilis Gervais 1853, off the coast of Ceará State, Brazil

Abstract

The gray dolphin (Sotalia fluviatilis Gervais 1853) is the most common cetaceon species off the coast of Ceará state. Between 1992 and 1997, 52 stranded animals were recorded in the State. The osteologic morphology and morphometry of 33 skulls of S. fluviatilis were analyzed, with emphasis on the most particular characteristics for this species as well as the ones that indicates agging, which provide indications of physical osteological maturation. The skully characterization was performed using 40 standard measurements. With the result obtained a judgment of physical maturation based on levels of ossification between skull structures and sutures observed on juveniles and adults. Using a comparative analysis between the values obtained here and other authors results it was possible to establish differences between the values of supposed different populations. The stidied specimens had low variation for most of the measurements, which characterize a single population based on the amplitudes obtained. It is necessary a future skully characterization of animals from other regions to confirm that the present methodology is effective for differring populations.