OSTEOHISTOLOGY OF A NEW SAUROPODOMORPH DINOSAUR FROM ANTARCTICA

The purpose of this study is to use the microstructure of bone to look at the growth of a small basal sauropodomorph dinosaur from the Early Jurassic Hanson Formation of Antarctica. This specimen is very small (femur length= 235.5mm), but bone histology can determine if it’s a juvenile, or if it represents a mature specimen of a small- bodied species. Cross sections of the femur, fibula, two ribs (one longitudinal study), and two gastralia were prepared through standard paleohistological techniques at The Field Museum of Natural History in Chicago. These sections displayed highly vascularized fibrolamellar tissue corresponding to rapid growth, common in most sauropods. Primary osteons are present with few secondary osteons indicative of remodeling present. No growth marks or annuli, such as lines of arrested growth (LAGs), were observed in the limb bones, but 1-2 were present asymmetrically in the gastralia and ribs. Since this specimen displayed rapid growth with little evidence of LAGs, histology suggests this animal died at an early ontogenetic stage. Histology can be used to determine if high latitudes had any effect on the growth of this dinosaur by comparing it to histological studies of related species living in lower latitudes. In this study, comparisons have been made to Mussaurus patagonicus, Plateosaurus engelhardti, and Massospondylus carinatus.