The sauropods were quadruped animal that ranged from the relatively small (approximately 23 feet [7 meters] long) to the longest land animals ever known (up to 131 feet [40 meters] long; although it is thought that some sauropods reached 180 to 200 feet [55 to 60 meters] in length). They had very long tails and necks, five-toed “hands” and feet, massive limbs, very small heads, and peg-like teeth. Sauropods were herbivorous, and had the lowest ratio of brain-to-body mass (called the encephalization quotient) of all the dinosaurs. These animals first appeared in the Early Jurassic period; by the Late Jurassic period, they had reached the pinnacle of their evolution and diversity.