One of the most frequent questions asked by creationists (of any stripe) is “Where are the transitional fossils?” They usually point, somewhat dismissively, at specimens such as Tiktaalik and ask for more. They claim that there should be thousands, if not hundreds of thousands of intermediate forms and hence many more transitional fossils than what makes it into the newspaper. This betrays a fundamental lack of knowledge about evolutionary theory in general and paleontology in particular. Outside of a few spectacular examples, most fossils, whether they be transitional or otherwise, never make it into the news. Rather they get descibed and discussed in journals such as The Journal of Vertebrate Paleontology, Paleobiology. and other specialized journals devoted to paleontology. How many of you have heard of Messelastur gratulator? Messelastur gratulator is a member of the sister taxon to owls and shows some morphological traits that link them to Falconiformes as well. Or Martinogale? Martinogale is one of the earliest New World skunks known and is close to the origins of all new world skunks. Of course, one could also find them in places such as Faunmap, Miomap, and The Paleobiology Database. You can also find them by searching the databases of many museums and universities. Although all of these methods can be time consuming and require more research skills than what creationists and intelligent design advocates seem to be able to muster.
So I was happy to receive a review copy of Donald Prothero’s Evolution: What the Fossils Say and Why It Matters. The book is divided into two sections. The first sections contains chapters on the nature of science, the fossil record, the growth of evolutionary theory, systematics, and creationism. Each chapter provides some interesting material for those who are not very familiar with the subject. The first chapter on the nature of science, for example, covers the scientific method, the difference between the scientific use and the vernacular use of the word “theory”, belief systems and science, the supernatural, and pseudoscience and baloney detection. This chapter and several others make liberal use of Carl Sagan quotations, which won me over immediately. The chapter on systematics is, in my opinion, worth the price of the book. Starting with an overview of what systematics and taxonomy are, the chapter discusses cladistics, the impact of molecular biology on classification, the tree of life, and an interesting section on “Ancestor Worship.” In this section Prothero makes several important points:
Some aspects of cladistic theory have proven more difficult for many scientists to accept. For example, a cladogram is simply a branching diagram of relationships between three or more taxa. It does not specify whether one taxon is ancestral to another; it only shows the topology of their relationships as established by shared derived characters… The nodes are simply branching points supported by shared derived characters, which presumably represent the most recent hypothetical common ancestor of the taxa that branch from that node. But strictly speaking, cladograms never put real taxa at any nodes, but only at the tips of branches.
The important question you should be asking is “why?” Prothero supplies the answer a few paragraphs later (and this is the important part of the section):
But there’s another reason why cladists avoid the concept of ancestry. To be a true ancestor, the fossil must have nothing but shared primitive characters relative to its descendants. If it has any derived feature not found in a descendant, it cannot be an ancestor.
The importance of this point will not be lost on anyone who has debated human evolution, or discussed transitional species, with creationists. I have refrained from mentioning the chapter on creationism, technically the third chapter, till now. Anyone who follows the attempts of creationists to undermine science will be familiar with the material covered in this chapter. Prothero makes liberal use of Talk Origins and the chapter reads like an extended entry on The Panda’s Thumb.
This brings us to the second part of the book, called “Evolution? The Fossils Say Yes.” As you may surmise from the title, this is a play on Gish’s book and Gish, among others, comes in for some heavy criticism. There is, however, more to the section than bashing Gish. In eleven chapters Prothero presents the fossil evidence for the origin of life, discusses the Cambrian slow burn, invertebrate transitions, the origins of the vertebrates, the origins of fish, amphibians, reptiles, mammals, dinosaurs, and birds. He also discusses the evolution of ichthyosaurs, plesiosaurs, and mosasaurs, the evolution of snakes and crocodiles, whales, horses, rhinoceros, titanotheres, elephants, and hominids, just to touch on a few examples. Even more valuable is the photographic evidence. The book is lavishly illustrated with fossils of every type and provide powerful supporting evidence for the text. Over and above that are the superb illustrations by Carl Buell – paleoartist extraordinaire. Oh and I almost forgot, along the way Prothero provides the most efficient and complete refutation of creationist accounts of the origin of the Grand Canyon I have ever seen. It was a thing of beauty.
Overall, the book is well written, well organized and makes a powerful case for evolution. It is definitely a worthy addition to the anti-creationist literature and fills a much needed gap. It is also an excellent book for the average lay person interested in evolutionary biology and paleontology.