North America is the source of much of what humanity knows about geologic time periods. The geographic area that would later become the United States has been the source of more varieties of dinosaurs than any other modern country. According to paleontologist Peter Dodson, this is primarily due to stratigraphy, climate and geography, human resources, and history. Much of the Mesozoic Era is represented by exposed outcrops in the many arid regions of the continent. The most significant Late Jurassic dinosaur-bearing fossil deposit in North America is the Morrison Formation of the western United States.
- ^ "North America". Encyclopaedia Britannica. http://www.britannica.com/EBchecked/topic/418612/North-America.
- ^ a b c d Dodson, Peter (1997). "American Dinosaurs." Encyclopedia of Dinosaurs. Edited by Phillip J. Currie and Kevin Padian. Academic Press. p. 10-13.
- ^ Weishampel, David B; et al (2004). "Dinosaur distribution (Late Jurassic, North America)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 543–545. ISBN 0-520-24209-2.