Authors: Isaac Wilson, Bree Wilson
Mentors: Arianna Harrington
Insitution: Southern Utah University
Understanding the body size of an organism is crucial for discussing its ecological role, potential trophic impact on its environment, and life history. The sauropod dinosaurs represent the largest land animals known, reaching masses many times that of modern elephants and rivaling the most massive cetaceans in some cases. This study attempts to quantify the body size variation between average and maximum sauropod dinosaurs by using Camarasaurus as a focal genus and comparing appendicular elements from the same quarries. Intraquarry rather than intraspecific variation is chosen due to the difficulty of diagnosing limb elements to the species level, and limb elements are known to scale isometrically in Camarasaurus. In addition to Camarasaurus-centric measurements, extant and extinct ecological analogues with recorded body size ranges are also used to estimate body size variation. While their life histories are not well-known, histological analysis indicates that sauropods were likely tachymetabolic endotherms, and their growth curves were most similar to birds and large herbivorous mammals in terms of extant taxa. This is in contrast to basal sauropodomorphs like Plateosaurus, which is demonstrated to exhibit high developmental plasticity. Minimum intraspecific size variation, collected from the literature and based on birds, nonavian dinosaurs, and large herbivorous mammals suggest that the largest representatives of any given sauropod species could have been between 139% and well over 200% larger than the average. Applying preliminary ratios from the data collected so far to the largest well-preserved sauropod, Argentinosaurus huinculensis, results in a plausible maximal mass of 137-177 tonnes for the genus.