Natural History of Human’s Most Distant Living Mammalian Relatives

Abstract

In comparison to the more than 1,200 genera of placentals and marsupials, the three extant monotreme genera make up only a tiny part of modern mammalian diversity. However, the significance of monotremes to mammalian evolutionary history and biology is far more than can be measured by their few genera. The evolutionary stature of monotremes as the first group to diverge among extant mammal lineages has been corroborated by an overwhelming body of scientific evidence from fossils, comparative morphology, and molecular information on the genomic scale. With their highly specialized physiological and functional adaptations, distinctive developmental pattern and karyotypes, these egg-laying mammals push the envelope of human imagination regarding what is possible for mammalian biological diversity. For evolutionists, monotremes represent the extant phylogenetic bracket for the common ancestor of all modern mammals (crown Mammalia). For physiologists and functional morphologists, monotremes give meaning to mammalian structural and functional diversities. For ecologists and conservation biologists, the monotremes are an integral element of an ecosystem on Gondwanaland from the deep times of the Earth. Since the echidna and platypus became known to western science in 1792 and 1800, respectively, monotremes have always fascinated the scientific community and the public (Moyal 2001). But monotremes are more than a curiosity—they are an indispensable group for all scientists in pursuit of any area of mammalian comparative biology to consider. In Echidna—An Extraordinary Egg-Laying Mammal, Michael Augee, Brett Gooden, and Anne Musser have written an excellent primer on the biology and natural history of the shortbeaked echidna—Tachyglossus aculeatus or the spiny anteater. This book of 136 pages is a concise, informative, and immensely readable review of the structure, function, physiology, behavior, and life history of the echidna. It is well aimed at a general scientific readership and contains very interesting information on all aspects of the natural history and biology J Mammal Evol (2007) 14:283–285 DOI 10.1007/s10914-007-9059-1