As indicated by their highly vascularized fibrolamellar bone (but also by estimates from rare growth marks and estimates from local bone tissue apposition rates), growth rates of sauropods were comparable only to those of large herbivorous mammals and birds, suggesting that sauropods were tachymetabolic endotherms. Evolution of large body size in sauropods was brought about by an increase in growth rate and evolution of tachymetabolic endothermy, which was only incompletely developed in basal sauropodomorphs. The smallto medium-sized titanosaurs Phuwiangosaurus and Ampelosaurus show a reduced growth rate compared to other neosauropods. The dwarfed island forms Europasaurus and Magyarosaurus evolved their diminutive body size by a decrease in growth rate and, in the case of Europasaurus, a shortening of the active phase of growth.