From: Two Medicine Formation, Teton County, Montana Albertosaurus is a genus of tyrannosaurid theropod dinosaurs that lived in western North America during the Late Cretaceous Period, about 70 million years ago.   23.3 grams, Display measure: 3.5 x 1 x 4.75 inches

Allosaurus Fragilis jurassic age : 145-201 Million Years Old, Morrison Formation ColoradoThe first big meat-eating predator discovered in the Morrison Formation, predates Tyrannosaurus rex.   341.3 grams, 16 x 2 x 1 inches

Age: Cretaceous Age 67.5 - 65 Million years old From: Judith River Formation, Blaine County, Montana Nanotyrannus ("dwarf tyrant") is a potentially dubious genus of tyrannosaurid dinosaur. It is known only from two specimens (possibly three), which are potentially juvenile specimens of the contemporary genus Tyrannosaurus rex.   23.3 grams, Display measure: 3.5 x 1...

Age: Cretaceous Age 67.5 - 65 Million years old From: Hell Creek Formation, Harding County, South Dakota Nanotyrannus ("dwarf tyrant") is a potentially dubious genus of tyrannosaurid dinosaur. It is known only from two specimens (possibly three), which are potentially juvenile specimens of the contemporary genus Tyrannosaurus rex.   23.3 grams,...