The Black-tailed Jackrabbit (Lepus californicus) is the third largest hare common in the western United States and Mexico and weighs from 3 to 6 lbs. The young are mobile within minutes of birth, so mothers do not protect or stay with the young rabbits except during nursing. The Black-tailed Jackrabbit is an important prey species for raptors and carnivorous mammals, such as eagles, hawks, owls, coyotes, foxes, and wild cats. The rabbits host many ectoparasites including fleas, ticks, lice, and mites. Consequently, hunters generally avoid harvesting them for food.

            Tyrannosaurus (“tyrant lizard”, from the Ancient Greek tyrannos, “tyrant”, and sauros, “lizard”) is a genus of coelurosaurian theropod dinosaur. The species Tyrannosaurus rex (rex meaning “king” in Latin), commonly abbreviated to T. rex, is one of the most well-represented of the large theropods (animals that had short forelimbs and walked or ran on its hind legs). Tyrannosaurus lived throughout what is now western North America, so it is appropriately added to this collection of western United States animals, though extinct.  Fossils are found in a variety of rock formations dating to the upper Cretaceous Period, 68 to 66 million years ago.