We can also point out that meteors sometimes contain amino acids, as well. For instance, the Murchison meteorite contained small amounts of guanine, adenine, and uracil; however, no cytosine. These also contained less than 15 parts per million. However, we can also point out that some of these meteors with amino acids are actually returning from the early Earth. Rana, Fazale, and Hugh Ross. Origins of Life: Biblical and Evolutionary Models Face off. Colorado Springs, CO: NavPress, 2004. 95-96.