Terrestrial animals are generally either ureotelic or uricotelic, not ammonotelic, why?

Explanation

Ammonotelism involves loss of large amount of water (e.g. 500 ml of water to expel one gram of ammonia). Terrestrial animals cannot lose such a large amount of water so these switch over either to ureotelism (e.g.mammals) or uricotelism (e.g.insects,birds and terrestrial reptiles) for conservation of water.