Using osteological measurements to estimate body length in Amazonian manatees

ABSTRACT Body length is an important parameter in morphological, ecological and behavioral studies of a species and contributes to the understanding of the body condition of individuals. This parameter is essential for conservation and management strategies by informing studies evaluating growth rates, physical maturity and classification of individuals into age groups, promoting better accuracy for the biological parameters of the species. The aim of this study was to identify predictors of body length for Amazonian manatees (Trichechus inunguis) using metric characters of osteological materials. Eleven linear measurements of skull, jaw, scapulae and humeri were collected from 41 Amazonian manatee skeletons of different age classes (calf, juvenile and adult). Data were analyzed by simple linear regression. The condylobasal length was the best predictor of body length for the species (R = 0.943), however, all bones evaluated showed at least one measurement with the capacity to predict body size (R2 > 0.9). Results of this study are useful for inferring body length of Amazonian manatees using bones deposited in museums and biological collections, expanding the informative potential of these materials.

摘要：体长是物种形态学、生态学与行为学研究的重要参数，有助于解析个体的身体状况。该参数可为物种保护与管理策略提供关键支撑：通过助力生长速率评估、生理成熟度判定及个体年龄组划分等相关研究，提升该物种生物学参数估算的精准度。本研究旨在利用骨骼标本的测量特征，预测亚马逊海牛（Trichechus inunguis）的体长。研究人员从41具覆盖不同年龄阶段（幼崽、亚成体与成体）的亚马逊海牛骨骼标本中，采集了颅骨、下颌骨、肩胛骨及肱骨的11项线性测量数据，并采用简单线性回归方法开展数据分析。结果显示，颅基底长是该物种体长的最佳预测指标（R=0.943）；不过所有被测骨骼均至少存在一项可用于预测体尺的测量参数（决定系数R²>0.9）。本研究结果可为利用馆藏于博物馆及生物标本馆的骨骼标本推断亚马逊海牛的体长提供依据，进一步拓展了此类标本的信息利用潜力。