Scientists say they have discovered new details about young Tyrannosaurus rex dinosaurs. Researchers examined fossilized skeleton samples from two small Tyrannosaurus rex also known as T. rex. The skeletons were discovered in the western American state of Montana in the early 2000s. Researchers named the two dinosaurs Jane and Petey. Each T. rex was estimated to have stood a little taller than a horse and was about twice as long. The researchers say the fossilized bone samples have helped them better understand the history and development of this famous dinosaur. The findings are described in a study recently published in Science Advances.