Class amphibians, order anura contains all the frogs and toads in the world. These creatures are defined by their large eyes, moist skin, relatively large hind legs, and lack of tail. Amphibians diverged from their closest primordial relatives, the lobe-finned fishes, in the Devonian era as the first tetrapods to set foot on land1. Examining the morphology of these animals can clarify much of what made amphibians excellent candidates for terrestrial colonization. They had toes that allowed them to walk (albeit clumsily) on land, lungs that allowed them to breathe the air above them, and the beginnings of a neck that allowed them to spring when prey moved. Over time the clade diversified and Vieraella Herbstii, the first known tailless "true frog", appeared in the Late Jurassic2. The appearance of V. Herbstii marked the beginning of the Anura order. Like all amphibians, Anurans do not have the ability to produce amniotic eggs. Because they are unable to lay their eggs on land, nearly all organisms in this class spend their lives near a source of fresh water. Frogs need fresh water to lay eggs and pass on their genes, but without a ready source nearby, any frog offspring will dry out. Another limitation that all amphibians, excluding frogs, face is the fact that their skin is vital to their respiration. They absorb O2 and release Co2 through their porous coating and to do this they need to stay moist3. Desiccation is a very real threat to all amphibians, which is why they are largely found in tropical environments and other areas with high humidity and precipitation. Frogs are all carnivores that feed primarily on arthropods such as insects and spiders, but some of the larger breeds may prey on small mammals and birds. Their s......middle of paper......//sci.waikato.ac.nz. The University of Waikato, nd Web. 31 March 2014. .[2] Evans, SUSAN E., ANDREW R. Milner and FRANCES Mussett. "A discoglossid frog from the Middle Jurassic of England." Paleontology 33.2 (1990): 299-311.[3] Reece, Jane B. and Neil A. Campbell. Campbell Biology / Jane B. Reece ... Boston: Benjamin Cummings, 2011. Print.[4] Levine, R.P. "Contribution of eye retraction to swallowing performance in the northern leopard frog, Rana Pipiens." Journal of Experimental Biology207.8 (2004): 1361-368. Print.[5] Fryer, Benjamin. "Rana Pipiens." AmphibiaWeb.com. Amphibiaweb, 4 June 2004. Web. 03 April 2014.[6]Gilbert SF. Developmental biology. 6th edition. Sunderland (MA): Sinauer Associates; 2000. The life cycle of the frog. Available from: http://www.ncbi.nlm.nih.gov/books/NBK10035/