Palaeobiology of the early sauropodomorph <i>Mussaurus patagonicus</i> inferred from its long bone histology

Abstract We present a detailed histological study of long bones from an ontogenetic series Mussaurus patagonicus , early sauropodomorph the Lower Jurassic Argentina. Twenty bones, including humeri, femora and fibulae, obtained 13 individuals different body sizes were sampled for analysis. In general terms, cortical bone is formed by well vascularized fibrolamellar parallel fibred bone. Except smaller individuals, cyclical growth marks (CGMs) are recorded in all specimens but their number relative position highly variable. exhibits marked variation regarding rate, with some growing much faster than others. Such affects size adult which results poor correlation between age/ontogenetic stage this taxon. These discrepancies may be related to sexual dimorphism and/or developmental plasticity. Intraspecific also regard strategies, can vary cyclical, as other sauropodomorphs, continuous, reported sauropods. Sexual maturity appears have been reached 23 31 years, delayed comparison sauropodomorphs more comparable derived The attainment somatic at about 14 years after onset maturity. sauropodiform, phylogenetically closer sauropods most Early therefore provides critical information understanding palaeobiological aspects origin gigantism lineage.