The formation of the western deserts is believed to have begun in Miocene times and continued through Pliocene and into early Plesitocene times (Milstead 1960). By mid-Tertiary the Chihuahuan desert was an arid place but did not reach current state of aridity until the early Pleistocene. The present conditions of aridity of the Chihuahuan desert probably existed throughout the Pleistocene, and were interrupted at times by pluvial periods. It was during these pluvial periods that invading organisms made their way to the valley floor.
The Cuatro Ciénegas basin provided an area of abundant surficial waters within the arid desert and as such, acted as a refugia - an evolutionary island oasis. Studies have concluded that the basin is an ancient aquatic environment, that has maintained relative environmental stability throughout at least the last 30,000 years. Within this stable, island, evolutionary changes are apparent. The variety of aquatic habitats found within the basin provide a refuge for a variety of mesic plants and animals found there. The high degree of endemism provides evidence of ancient relict populations that have undergone evolutionary change. Whereas, relict species that are undifferentiated from their main populations provide evidence of recent invasions of the basin. The basin acts as a refugia for both the endemic and relict populations.
Calegari, Valerie. 1997. Environmental Perceptions and Local Conservation Efforts in Cuatro Cienegas, Coahuila, Mexico. Masters of Arts Thesis, Department of Geography, The University of Texas at Austin, Austin, Texas.
Grall, George. 1995. Cuatro Ciénegas: México's desert aquarium. National Geographic, 188(October): 85-97.
McCoy, C.J. 1984. Ecological and zoogeographic relationships of amphibians and reptiles of the Cuatro Cienegas basin. Pp. 49- 60, in Paul C. Marsh (ed.). Biota of Cuatro Cienegas, Coahuila, Mexico: Proceedings of a Special Symposium. Fourteenth Annual Meeting, Desert Fishes Council, Tempe, Arizona USA, 18- 20 November 1983. Journal of the Arizona- Nevada Academy of Science 19(1).
Meyer, Edward R. 1973. Late- Quaternary paleoecology of the Cuatro Cienegas basin, Coahuila, Mexico. Ecology 54:982- 995.
Meyer, Edward R. 1975. Vegetation and pollen rain in the Cuatro Cienegas basin, Coahuila, Mexico. The Southwestern Naturalist 30(2):215- 224.
Milstead, William W. 1960. Relict species of the Chihuahuan Desert. The Southwestern Naturalist 5(1):75- 88.
Minckley, W 1969. Environments of the Bolsón of Cuatro Cienegas, Coahuila, Mexico, with special reference to the aquatic biota. Texas Western Press, University of Texas El Paso Science Series 2:1- 65.
Minckley, W 1978. Endemic fishes of the Cuatro Cienegas basin, Coahuila, Mexico.Pp. 383- 404, in Roland H. Wauer & David Riskind (eds.). Symposium on the Biological Resources of the Chihuahuan Desert Region, United States and Mexico. U.S. National Park Service Transactions and Proceedings Series 3(1977). Government Printing Office, Washington, District of Columbia USA.
Minckley, W 1992. Three decades near Cuatro Cienegas, Mexico: Photographic documentation and a plea for area conservation. Pp. 81- 110, in Milton R. Sommerfeld & Dennis M. Kubly (eds.). Limnology and Aquatic Biology of the Southwest, Proceedings of a Special Symposium to Honor Professor Gerald Ainsworth Cole. Thirty- fourth Annual Meeting of the Arizona- Nevada Academy of Science, Tempe, Arizona, 21 April 1990. Ibid. 26(2).
Pinkava, Donald J. 1969. Preliminary investigations of the flora and vegetation of the Cuatro Cienegas Basin, Coahuila, Mexico. Proceedings Supplement, Journal of Arizona Academy of Sciences 1969:13 (abstr.).
Pinkava, Donald J. 1978. Vegetation and flora of the Cuatro Cienegas basin, Coahuila, Mexico. Pp. 327- 333, in Roland H. Wauer & David Riskind (eds.). 1978. Transactions of the Symposium on the Biological Resources of the Chihuahuan Desert Region, United States and Mexico. U.S. National Park Service Transactions and Proceedings Series 3(1977). Government Printing Office, Washington, District of Columbia USA.