Ultrasauros was a huge, plant-eating dinosaur that had a giraffe-like stance. It is one of the tallest and largest dinosaurs yet found. Ultrasauros is a dubious genus; the Ultrasauros fossil may actually be composed of two separate dinosaurs, Brachiosaurus and Supersaurus. Both of these dinosaurs were enormous, four-legged plant-eating dinosaurs with a long neck and long tail.

When Ultrasauros Lived: This giant sauropod dates from the late Jurassic period.

Anatomy: Ultrasauros walked on four legs and, like the other Brachiosaurids and unlike most dinosaurs, its front legs were longer than its hind legs. Ultrasauros is estimated to be about 82-100+ feet long (25-30 m), about 50 feet (15 m) high, weighing 55 to 130 tons. It had a claw on the first toe of each front foot and claws on the first three toes of each rear foot (each foot had five toes with fleshy pads). Like other Brachiosaurids, it had chisel-like teeth, its nostrils were on the top of its head, and it had large nasal openings indicating that it may have had a good sense of smell.

Fossils and Name: Just a few bones of "Ultrasauros" were found in the Upper Jurassic Morrison Formation western Colorado, USA, in 1979, by US paleontologist James A. Jensen (who also discovered Supersaurus in 1972). Jensen named it Ultrasaurus in 1985 (meaning "Ultra lizard"). It was renamed Ultrasauros machintoshi because there was already another dinosaur named Ultrasaurus (a smaller, early Cretaceous sauropod found in South Korea and named by Haang Mook Kim in 1983).