Sauropod << SAWR uh pahd >> is the name for a group of large, herbivorous (plant-eating) dinosaurs. The group includes some of the best-known dinosaurs, including Apatosaurus, Diplodocus, Brontosaurus, and Brachiosaurus.
The name sauropod comes from Sauropoda, an infraorder (level of scientific classification) of saurischian (lizard-hipped) dinosaurs. Sauropod means lizard foot.
Anatomy.
Sauropod dinosaurs had long necks, pillarlike legs, and long tails. The largest sauropods reached a greater body size than any other land animal. Among some sauropods, body length exceeded 115 feet (35 meters) and body weight ranged from 77 to 99 tons (70 to 90 metric tons). To bear such enormous weight, sauropods had specialized limbs. They had massive thigh bones, and their foot bones were arranged in a columnlike fashion. The bones of their long necks had a system of air sacs that made respiration more efficient and helped reduce weight. To reach such great dimensions, sauropods had to eat a great deal of vegetation daily. Their teeth, which they used to rake in vegetation, were shed and replaced throughout their lives.
Some sauropods had shorter necks than others, but all sauropods shared a basic body plan. Sauropods occasionally entered aquatic or near-shore habitats, but they primarily spent their time on land. Fossil sites, such as the Morrison Formation in the western United States, show that several sauropod species lived side by side in diverse communities. Preserved footprints suggest that some sauropods moved together in herds.
A subgroup of the sauropods, called titanosaurs, were among the last of the sauropods. They were widespread, especially in what is now South America. Fossils of one titanosaur species, called Patagotitan mayorum, were discovered in the South American country of Argentina in 2013. In life, this dinosaur was about 120 feet (36.5 meters) long and weighed about 69 tons (62.5 metric tons). Paleontologists (scientists who study fossils) estimate that Patagotitan was the largest land animal to ever walk the Earth.
Reproduction.
Like other dinosaurs, sauropods laid eggs. Sauropod eggs were relatively small compared with the huge size of adult sauropods. Young sauropods grew at an extremely fast rate to reach their enormous adult size.
Scientists have discovered large sauropod nesting grounds that preserve sauropod eggs and information on sauropod reproduction. The Auca Mahuevo site in Argentina is particularly important. This site preserves fossil remains of sauropod embryos and details of the shape and spacing of nests.
Fossil record.
Sauropod fossils have been found on all continents, even Antarctica. The earliest sauropod fossils are found in sediments that date to the early part of the Jurassic Period, about 200 million years ago. Sauropods became extinct with other dinosaurs at the end of the Cretaceous Period, 66 million years ago.
