Who better than an elder of science can describe the quirks and clevernesses of those who made the field? Distinguished paleontologist Simpson, a vigorous octogenanian, has already written his autobiography (Concession to the Improbable) and a general work on his specialty, South American mammals (Splendid Isolation). Here he chronicles South American paleontology from the earliest discoveries, at the end of the 19th century, to the present--with overmuch technical detail for the general reader, perhaps, but also much color and interesting content. His narrative begins with the dual findings of a ""megalonyx"" in Virginia and a megatherium in South America: two sloth-like fossils that caught the eye of no less than Jefferson in Virginia and Cuvier in France. Megatherium became the first South American fossil to be properly named, and the first in the world to be mounted as such and displayed. Darwin, of course, set foot in South America, but his small collections of fossils were not pivotal to evolutionary theory. He did nonetheless make one notable observation: he found a fossil of an extinct horse species side by side with other mammalian fossils, establishing that horses had existed on the continent before the Spanish invasion. Especially interesting are Simpson's chapters on the Ameghino brothers of Argentina. Flamboyant Florentino and retiring Carlos amassed major museum collections of fossil mammals using their own money--from family-owned bookstores--to finance their work. As the generations advance, some familiar names appear--Edward Drinker Cope, Othniel Marsh, Henry Fairfield Osborn, Barnum Brown--but Simpson's scholarship is almost more satisfying in filling in the gaps on the lesser-known figures. Such a work helps to give the development of a science full human dimension.