MODERN
Google, I. (n.d.). Google Image Result for http://www.animalfactguide.com/images/maps/worldmap_echidna.png.Google. Retrieved June 27, 2011, from http://www.google.com.hk/imgres?imgurl=http://www.animalfactguide.com/images/maps/worldmap_echidna.png&imgrefurl=http://www.animalfactguide.com/animalfacts/short-beaked-echidna/&usg=__S3JllEmZ2IiRpxMnxtq6Z8P7S8k=&h=305&w=560&sz=19&hl=en&start=0&sig2=Jn4vc

Government, A. G. (2011, November 11). Unique Australian Animals. Unique Australian Animals. Retrieved July 27, 2011, from http://australian-animals.net/echidna.htm
ANCIENT

Learning, E. (n.d.). Echidna/Spiny Anteater Printout- EnchantedLearning.com.ENCHANTED LEARNING HOME PAGE. Retrieved June 27, 2011, from http://www.enchantedlearning.com/subjects/mammals/echidna/Echidnaprintout.shtml

Museum, A. (n.d.). The Mesozoic Era (251 - 65 million years ago) - Australian Museum. Australian Museum - nature, culture, discover - Australian Museum. Retrieved June 27, 2011, from http://australianmuseum.net.au/The-Mesozoic-Era

Museum, A. (n.d.). Steropodon galmani - Australian Museum.Australian Museum - nature, culture, discover - Australian Museum. Retrieved June 27, 2011, from http://australianmuseum.net.au/Steropodon-galmani

Russell, M. (n.d.). Characteristics of Mammals.EzineArticles Submission - Submit Your Best Quality Original Articles For Massive Exposure, Ezine Publishers Get 25 Free Article Reprints. Retrieved June 27, 2011, from http://ezinearticles.com/?Characteristics-of-Mammals&id=244501

Strauss, �. (n.d.). Steropodon - Prehistoric Mammal Steropodon Characteristics, Behavior and Habitat.Dinosaurs - Types, Behavior and Evolution of Dinosaurs. Retrieved June 27, 2011, from http://dinosaurs.about.com/od/mesozoicmammals/p/Steropodon.htm

Temp, C. (n.d.). Australia Climate Information - ClimateTemp.info, Making Sense of Average Monthly Temperature & Weather Data with Detailed Climate Graphs That Portray Average Rainfall & Sunshine Hours. World Weather and Climate graphs, average climate charts, guide to precipitation, temperatures, best, friendly, holiday climate. Retrieved June 27, 2011, from http://www.climatetemp.info/australia/
FUTURE

The echidna has a four-headed penis « Why Evolution Is True. (n.d.). Why Evolution Is True. Retrieved June 27, 2011, from http://whyevolutionistrue.wordpress.com/2009/06/13/the-echidna-has-a-four-headed-penis/

Time, A. T. (n.d.). Monotremes. A biography of the Australian continent. Retrieved June 27, 2011, from http://austhrutime.com/monotremes.htm

keeper, F. (n.d.). Monotremes- First mammals. monotremes- first mammals. Retrieved July 11, 2011, from https://ferrebeekeeper.wordpress.com/tag/mesozoic/

newborn, w. o., narrow, t. a., worms., acculeatus, i. l., snout, e., short., et al. (n.d.). Echidnas. north american wildlife | pets. Retrieved June 27, 2011, from http://www.petandwildlife.com/monotremes/echidnas.html
snout., a. l. (n.d.). Life History and Ecology of the Monotremata. UCMP - University of California Museum of Paleontology. Retrieved June 27, 2011, from http://www.ucmp.berkeley.edu/