The Rise of Animals: Evolution and Diversification of the Kingdom Animalia, Mikhail A, Fedonkin, James G. Gehling, Kathleen Grey, Guy M. Narbonne, Patricia Vickers-Rich. The John Hopkins University Press, Baltimore, Maryland, 2007, $75.00, large format hard-cover; 326 pp. Includes an Atlas of Precambrian Metazoans covering some thirty-six pages, a twenty-one page Bibliography, and a twelve page Index.
The Rise of Animals is organized in four main sections: Part 1, The Background: The Archean and Proterozoic Eons; Part 2, The Fossil Sites: Rare and Extraordinary; Part 3, Other Evidence of Animalia; and Part 4, A Dramatic Crossroads The Cambrian "Explosion"? Technical terms are generally defined in the text or in sidebars near first use in the text. The Rise of Animals is generously illustrated with 480 numbered figures that include photographs of fossils, sites and important researchers in action. In addition, the figures also include a number of illustrative charts and graphs that are primarily concentrated in Part 1.
Part 1 is subdivided into discussions of the Archean and Proterozoic Eons. The Archean ranges from 4.6 billion to 2.5 billion years B.P. This first chapter includes discussion of Earth's origin and its overall structure. There is a detailed explanation of how the earth stratified from the molten nickel-iron core out to the mantle and crust. The authors also cover the genesis of the oceans and the early atmosphere. Plate tectonics got its start in the Archean and explanation of that mechanism is presented here. The Proterozoic ranging from 2.5 billion to 542 million years B.P. is covered in the second chapter in Part 1. The earliest known supercontinent, Rodinia, preceded the more well known supercontinents Pangaea and Gondwana. The authors admit that further study is needed to allow consensus on the reconstruction of this most ancient landmass. It is in this section that the earliest Eukaryotic life forms are described as algal mats from as early as 1.7 billion years B.P. Snowball earth theories get exposure here too. There is an ongoing debate as to how extensive this ice age may have been. Some feel that the evidence supports the premise of ice covering the globe all the way to the equator. While Part 1 as a whole included explicit current information, greater depth in some areas would have been an enhancement. As written, too much is left to the reader to seek out the cited original sources.
Part 2 covers the bulk of The Rise of Animals. Here the Ediacaran fossils are presented in nine chapters covering nine worldwide locations. The Ediacarans represent the earliest Metazoans (multicellular animals). Despite my criticism of Part 1 of The Rise of Animals, Part 2 is very good and quite interesting. The Rise of Animals presents the reader with a comprehensive guide to Ediacaran age fossils with photographs and descriptions. Had you thought that the Ediacarans were represented by only a few contentious imprints from the Australian outback you will actually see them to be extensive in number and worldwide in distribution. Living between 575 and 542 million years B.P., just before the Cambrian Explosion, the Ediacarans have become the answer to Darwin's famous dilemma - why do the complex Cambrian life forms seem to spring from nothing with no known predecessors? Each chapter in Part 2 presents the history of exploration of the site being described and elaborates on the fauna itself. The photographs and reconstructions are excellent as is the text description of the animals. The authors also discuss the biology of the animals and the environmental conditions when the animals were alive. The locations included in Part 2 are:
Chapter3. The Ediacaran of the Avalon Peninsula of Newfoundland has the longest time range of any of the worldwide exposures as it covers 10 million years in time. Of all the other locations for Ediacaran fossils, Avalon is also unique in having been a deep water environment.
Many of the specimens are preserved in three dimensions. One of the more striking is a beautiful dendritic frond of an unnamed species, Figure 75 (57). One can easily visualize the possibility of this creature being related to the modern soft coral pictured later in Figure 181 (108).
Chapter 4. The Nama Fauna of Namibia is described as mostly attached sessile frond like creatures. While the fauna is preserved as internal molds, the mechanism allowing preservation of soft bodied creatures in this fashion is still not certain. The best idea is that the specific decomposing bacteria for their body composition had not evolved until later in the Cambrian.
Chapter 5. The term Ediacaran was derived from hills of that name in the Australian outback. The geology and fauna is covered in this extensive chapter. The Global Stratotype Section and Point for the base of the Ediacaran System is located in the Flinders Range just above a marker bed indicative of an ending glacial event. Australian geologist Red Sprigg is credited with some of the first finds of the Ediacaran fossils in the late 1940's. As often happens with new and revolutionary discoveries his was originally scoffed at by some of the experts of the time. Sprigg discovered Dickinsonia, a flattish, oval, radially ridged creature that he believed had been mobile. Subsequent discoveries of Dickinsonia in Russia and Australia verified this idea (95). Mobile creatures such as this fed on microbial mats that covered the sea floor. These mats are preserved as pebbly looking surfaces that the authors have termed "elephant skin" Figure 187 (110). Chapter 5 ends with an excellent summary of events leading up to the rise of animals as seen in the sedimentary record in the Australian Flinders Range.
Chapter 6. The White Sea area of northern Russia embodies one of the most extensive collections of Ediacaran fauna. This is one of those foreboding regions of the earth where it is either unbearably cold or hot and swarming with biting flies. The fauna described here are broad in their variety. There are also similar forms to those found in other regions of the world so that worldwide correlation is possible. One of the more important discoveries is illustrated in a photograph in Figure 230 (127) showing a Yorgia waggonerni, a form similar to Dickinsonia. The Yorgia has relocated itself several times, leaving somewhat bare spots, on the "elephant skin" mat before being preserved in place. A number of the Ediacaran fossil impressions are oval in shape with "beaded" borders (Kimberella sp.). Illustrations of a modern marine mollusk foot and a modern monoplacophoran (Figures 256 through 259 (139)) are very similar to the Kimberella impressions giving rise to the idea that these Ediacarans may have been precursors to those younger forms. Another possible ancestor to later Paleozoic fauna is shown in Figures 272 and 273 (144) - Vendoconularia triradiata (illustrated but not discussed in the text until later in chapter 14 (247)).
Chapter 7. This short chapter describes the Podolia area of the Ukraine that at one time was thought to be of Silurian age. Included in the finds here are the microbial mats, Dickinsonia and spherical depressions thought to be anchors for frond-like fauna.
Chapter 8. Siberia has Ediacaran fauna to add to the Russian riches. This brief section describes a less diverse fauna. The most striking fossils shown are of the frond like species Charnia.
Chapter 9. Another wonderful sequence is in the Urals of Russia. Very few photographs of the fauna are shown but Dickinsonia is present as are holdfast structures. The authors want to compare the Ural exposures to the White Sea region. They hope that this scrutiny will deepen their understanding of the effects of climate and geographical differences on this early fauna.
Chapter 10. The last of the large locations to be discussed are the mountain exposures of western Canada. One of the most interesting fossils illustrated in Figures 344 and 345 (181) is that of a "worm" producing a meandering path through the microbial mat at the surface. Prior to the Cambrian, "worm" burrowing deep into the sediment has not been seen. Surface mining within the microbial mats by a bilaterally symmetrical creatures as exhibited here is typical of the time.
Chapter 11. Localities of smaller size are discussed within this section. Locations covered include England, Wales, California, Nevada, Arizona, North Carolina and various places in South America. The pre-Ediacaran embryo fossils from China are reported and illustrated (197). Even more worldwide localities are mentioned but they have not been extensively studied and their affinity to Ediacaran age has not been firmly established.
The first chapter in Part 3 is a mini-treatise on trace fossils and their interpretation. Examples of these in the Ediacaran are compared to modern or more recent known forms. The second and last chapter in Part 3 discusses the microfossil evidence of early life. Tracing these forms through time shows changes at glaciation and extraterrestrial impact events. This study has implications on global environmental conditions and inferences about the dramatic evolution at the Cambrian boundary.
Part 4 concludes The Rise of Animals with an overview of evolutionary relationships and possible descendants of the Ediacarans. Since their first discovery, the Ediacarans have been somewhat problematic in revealing their evolutionary relationships to each other and to their possible descendants in the Cambrian. The authors present differing views by numerous paleontologists of Ediacaran evolutionary relationships. It is hoped that consensus on a single version will eventually be reached. Right now that is not the case.
The Chinese embryonic fossils are analyzed here in more detail than in Chapter 11. They show very early stages in the embryonic process and illustrate embryonic forms of more complex animals. This indicates that the transition to a Metazoan fauna existed even prior to the Ediacaran.
The authors speculate about the "Cambrian Explosion" of 542 million years ago. What caused the fauna to develop mineralized skeletons? The mineralization could have been driven by environmental factors that altered ocean chemistry that was in turn influenced by geologic events. Some authors speculate that this instant "explosion" of forms actually developed over a 10 to 20 million year time period (247). Following this final chapter is an Atlas of Precambrian Metazoans. This is an excellent addition to The Rise of Animals. The Atlas provides an alphabetic listing of each of the known organisms with the localities at which they occur, the Formation in which they occur, other names by which they may be known, bibliographic references to their original description, location of the type specimens and how they have been classified. Each entry also includes a photograph of a fossil example and sometimes an additional reconstruction drawing.
The Rise of Animals provides an extensive look at the oldest Metazoan life on earth. The book is not without problems however. One of the problems is with the figures in Part 1 of The Rise of Animals and the presentation of diagrams, charts and graphs. Most, if not all of these, are credited as being from other authors' works and modified for this publication.
Unfortunately, the modification sometimes leaves out critical information such as the scale units (such as in Figure 21 (21)). Missing also are explanations that the original cited author would have undoubtedly included. Figures 35 through 38 (30, 31) all show various interpretations of the supercontinent Rodinia transforming to Gondwana through geologic time. The text mentions an "enormous ...Transgondwanan Mountain Chain...[that] eroded [and] gave rise to ... the Gondwana Superfan system" (30). Neither of these named features is labeled as such on any of these figures. The reader is left to seek out the original source cited as "Squire, et al, 2006b" (30). More care should have been taken to provide enough information within The Rise of Animals so readers aren't required to seek answers in a research library.
Another issue that is pervasive throughout The Rise of Animals is the lack of coordination between the text and the figures. While all of the 480 figures are numbered, none of them is referred to anywhere in the text. This leaves the reader quite frustrated, not knowing whether there is a helpful illustration to augment the text or not. Sometimes there is and sometimes there isn't but you won't know until you actually search. In one case I found an interesting illustration of Vendoconularia triradiata illustrated in Chapter 6 but not discussed in the text until later in chapter 14. Readability - Primarily for serious amateurs with most technical terminology defined within the text or in sidebars. The Rise of Animals contains considerable biological terminology so that a background in that area will be helpful. On the Upside - Primary coverage of the Ediacaran fauna with 480 figures that include mostly color images of fossils and localities plus charts and graphs. The Rise of Animals is a compendium of all known Ediacaran age occurrences so that it makes a very useful reference work.
Readability - Primarily for serious amateurs with most technical terminology defined within the text or in sidebars. The Rise of Animals contains considerable biological terminology so that a background in that area will be helpful.
On the Upside - Primary coverage of the Ediacaran fauna with 480 figures that include mostly color images of fossils and localities plus charts and graphs. The Rise of Animals is a compendium of all known Ediacaran age occurrences so that it makes a very useful reference work.
On the Downside - The 480 wonderful numbered figures are never referred to directly in the text so that the reader is left to constantly hunt for any supporting imagery. I found this to be a major oversight by the authors and editors.
Overall Rating - Recommended (with reservations based upon the issues raised concerning the numbered figures) for individuals wishing to learn more about the evolution of early life on earth and especially the worldwide Ediacaran fauna.
