Apatosaurus

Say it ah-PAT-oh-sore-us. The name means ‘deceptive lizard’.

Apatosaurus beside a person 1.75 m tall. Ticks mark every metre.Body shape drawn for this site, showing the general build of sauropods

Length: 21 m
Diet: Plant-eater
When: Late Jurassic152 to 145 million years ago
Fossils found in: USA
Named by: Marsh (1877)
Family tree: Dinosauria › Saurischia › Sauropodomorpha › Sauropoda › Diplodocoidea › Diplodocidae

Where Apatosaurus sits in the age of dinosaurs.Periods from the ICS chart; dinosaur dates from the Natural History Museum

Sauropods. Long-necked, four-legged plant-eaters, the biggest animals ever to walk on land. See all 59

Lived at the same time

Allosaurus · same country
Barosaurus · same country
Brachiosaurus · same country
Camptosaurus · same country
Ceratosaurus · same country
Coelurus · same country
Diplodocus · same country
Dryosaurus · same country

Other sauropods

Brachiosaurus Late Jurassic
Diplodocus Late Jurassic
Brachytrachelopan Mid Jurassic
Camarasaurus Late Jurassic
Dicraeosaurus Late Jurassic
Euhelopus Late Jurassic
Europasaurus Late Jurassic
Giraffatitan Late Jurassic

Source: Apatosaurus in the Natural History Museum Dino Directory, read 12 November 2026. Sizes are the museum's estimates for a typical adult. "Lived at the same time" lists dinosaurs whose dates overlap, which does not always mean they met.