Atlasaurus (AT-luh-SAWR-us - Atlas - the Titan who held up the heavens, according to Greek mythology + Greek sauros meaning "lizard") was a moderately large genus of sauropod dinosaur from Middle Jurassic (Bathonian to Callovian stages) beds in North Africa.
Atlasaurus was discovered by Monbaron, Russell & Taquet in 1999. It was named after the location of discovery in the High Atlas range of the Atlas Mountains of Morocco (where the Titan, Atlas was said to hold up the heavens), and for the animal's gigantic size (about 15 m (50 ft) long). It is known from a nearly complete skeleton with a skull found at Wawmda, in the Middle Jurassic (Bathonian-Callovian) Tiougguit Formation, Azilal Province, Tadla-Azilal region, Morocco.
The type species is Atlasaurus imelakei [ee-me-LAH-kay-ie], which comes from Arabic Imelake, the name of a giant; for a large animal found in North Africa.
A relatively primitive sauropod identified as a "cetiosaur" when first discovered in 1981, Atlasaurus appears to be closer to Brachiosaurus than to any other known sauropod based on detailed similarities between the vertebral column and limbs. It differs from Brachiosaurus, relative to the estimated length of the dorsal vertebral column (assuming 12 vertebrae, 3.04 m), in having a proportionately larger skull, a shorter neck (with at least 13 cervical vertebrae, shorter and more uniform in length than in Brachiosaurus), a longer tail and more elongated limbs (humerus to femur ratio: 0.99; ulna to tibia ratio: 1.15). The lower jaw is about 69 cm long; the neck about 3.86 m long; humerus 1.95 m long; femur about 2 m long; total estimated length: around 15 m (50 ft); estimated weight: 22.5 metric tons. The teeth are spoon-shaped and have denticles.