Allosaurus (Saurischia, Theropoda, Carnosauria) was designated the State Fossil in 1988 (Utah Code). S.B. 87, sponsored by Senator Omar Bunnel (D-Price), passed the House (66-0) and Senate (24-0) unanimously and was signed into law by Governor Norman Bangerter. In 2018, the Utahraptor was designated the Utah State Dinosaur.

Allosaurus lived 155 to 145 million years ago during the Late Jurassic Period (Kimmeridgian to late Tithonian ages). The name Allosaurus means “Different Lizard” and “Strange Reptile.” Allosaurus was a carnosaur, one of the groups of theropod meat-eaters. Allosaurus was the dominant predator of western North America. This dinosaur was large and probably too bulky to move at speed over any distance, however, the large sauropods and stegosaurs on which it fed were not fast-moving themselves. It measured around 16.5 feet in height and 39 feet in length and its skull more than 3 feet long; its jaws were lined with serrated, back-curved teeth and it weighed in at about 4 tons.

Allosaurus Scientific Classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Family: †Allosauridae
Subfamily: †Allosaurinae
Genus: †Allosaurus
Type Species: †Allosaurus fragilis

Allosaurus fossils were first discovered near Granby, CO and the Morrison Formation. Othniel C. Marsh gave these remains the formal name Allosaurus fragilis in 1877. Allosaurus specimens have been found in two of Utah’s quarries more than any other dinosaur. Sixty individuals, from juveniles to adults, were found at one site in Utah. 

The second species, Allosaurus jimmadseni, named for Utah’s first State Paleontologist Jim Madsen, is also found in the Morrison Formation. A third species, Allosaurus europeaus, has been identified in the Upper Jurassic Lourinha Formation on the coast of Portugal.