Mass Extinctions and Their Aftermath

A Thorough Introduction; Be Prepared to Work.:
Hallem and Wignell present a very detailed analysis of mass extinction. Unfortunately, it is too detailed for me. \oBut see my later notes, below, for more about that.\c I've never studied geology and there was much more detail than I could absorb. Also, the times are given in stages, not periods. "Late Devonian" I understand, but not "Frasnian-Famennian". But I did gain some insight into the relationship between geology and life, and I expect to read it again and gain more. Before I do that, I will make a chart of geologic time and, as I read the first chapters, I will write notes. If you're not an evolutionary scientist and you decide to read this book, I recommend you do the same. It starts out with a discussion of how one recognizes a mass extinction. For example, a decline in the numbers of fossils might just indicate that conditions for fossilization were less favorable, or it could accurately reflect a decline in numbers of species. The authors explain some ways to distinguish the two cases and settle on five periods which they consider to be real mass extinctions. Then there is a discussion of the tools used to search for possible causes of extinction. For example, a change in the ratio of carbon-13 to carbon-12 can indicate a decline in the amount of oxygen available for life. Or a change in sea level can lead to a rise in oxygen level. It will help you to make notes of anything in this section with which you are not already familiar. Finally, the book goes through each of the five major extinctions and examines each in terms of the tools. This is the bulk and payoff of the book. I was disappointed by one thing: there's not as much material as I would like on the aftermath mentioned in the title. I am very interested in this because I believe that, after a mass extinction clears away most animals, there is plenty of opportunity for new forms to evolve. There are quite a number of questions left unanswered and disputes unsettled. This may be frustrating to some readers, but it is inevitable in a book on current science. Creationists will call these "gaps"; Ph.D.s will call them job opportunities and many readers will think of them as "to be continued". \oOriginal review 9 Oct 2005; this paragraph 22 June 2006\c If this book sounds too technical for you, you might want to read the book Extinction: How Life on Earth Nearly Ended 250 Million Years Ago, by Douglas H. Erwin. (Click on "See all my reviews" for a review.) It's rather elementary, and it covers only the Permian extinction, but it has a lot of information. Furthermore, Erwin gradually introduces technical matters at a rate that many non-scientists can absorb. By the time you finish Erwin, you might want to read Hallam and Wignall. \oAdded 4 July 2006\c I have just finished reading this book for the second time. With the knowledge gained from the first reading, and with what I learned from Erwin's book, I found it much more readable. With my "jargon anxiety" greatly reduced, I was able to follow much of the remaining jargon with the help of charts in this book. \oFor example, "Frasnian" and "Fammenian" are now entirely familiar to me.\c Hallam and Wignall is aimed at advanced students, and there is much that I will probably never follow, especially regarding categories of marine invertebrates. But, not being a scientist, I don't need all of that. (E.g., I don't need to know the difference between rugose and scleractinian corals. The important thing is that one type went extinct at the end of the Permian and that the other eventually took over.) It's a great book for an interested non-scientist who likes to work at learning. And, yes, I did make some notes about the early material and I referred back to them often as I read. Regarding my disappointment over the shortage of material on recovery: on further consideration, what I really missed was material on how our mammal-like ancestors managed to squeeze through the Permian extinction. Thanks to both H & W and Erwin, I realize that evidence for this is just about non-existent.

A Good Overview of Mass Extinctions:
'Mass Extinctions and Their Aftermath' by A. Hallam and P. B. Wignall is a good overview of the episodes of mass extinctions in the history of life. Beginning with a brief primer on the 'anatomy' and significance of mass extinctions, the book covers both major and minor mass extinction events chronologically and succintly, with plenty of references. It summarizes the plausible cause (or causes) of these extinctions, as well as post-extinction recoveries. All-in-all, a slim volume which, through its compartmentalized structure and excellent reference database, provides a stepping stone to more specialized work.

Not For The Faint of Heart:
An excellent reference work for the devotee of paleontology. Should be read with your biology/botany/geology reference books in hand. Definitely a research work and at times, too scientific. Lacked continuity in some chapters (not surprising since the geological record is hazy at best) and could've been enhanced by chapter and overall summaries in layman's terms. If one's looking for an read along the lines of "Discovery Channel's" Age of the Dinosaurs, this is not the book to purchase. Well written, yes; as a good read, fair.

Superb presentation:
This book is not for the amateur interested in a general discussion of dinosaur extinctions. It's a professional text, probably intended for the paleontologist or paleontology student. If you're one of those whose avocation is along these lines, however, and you're able to read and understand the professional journals on the subject, it's full of information that you might find interesting and useful. If you're someone whose notion of a "journal" is Discover Magazine, you'll be bored to tears. This said, Wow! The topic of extinction is of course one of emotive interest to the general public, and of course because of this to the makers of TV documentaries and the authors of popular books on the subject. As Hallam and Wignall point out in Mass Extinctions and their Aftermath, popular interest in the extinction of the Cretaceous dinosaurs is way out of proportion to their importance as one of the world's life forms and certainly to their representation in the faunal fossil record, so the proliferation of documentaries and books specific to the life form misrepresents the significance of their demise. They also make it seem as though the "problem" is all settled--conveniently by the most dramatic event possible. Unfortunately this focus also makes it seem as though nothing else of significance happened in the rest of geologic history, which is patently untrue, as the authors make abundantly clear. They've gone a long way toward correcting the deficit in the literature, with the obvious proviso that non-professionals read the book. For the professional paleontologist, much of general geologic information is probably known to you. If you've been long in the field, but behind in your reading, the book will give you an excellent coverage of "what's new," and what is, is a lot. Certainly anyone looking to write a paper on a specific topic in extinction will find Hallam and Wignall's bibliography an excellent starting point for a literature search. The entries are comprehensive, global, and cover most theories. Just the thought of the amount of work involved in compiling this bibiliography, let alone sifting it for well executed research results, is exhausting to me. Presumably some of it was done by computer and some by student "slaves," but it still represents a major effort on the part of the authors, and I think the book shows it. For the paleontology student, the book is a well conceived text. It describes the divisions of the various biologic eras in a finer detail than I've seen done in textbooks in the past. Most importantly, it doesn't just leave a term like "Maastrichtian"--my favorite--hanging out there in limbo. The authors provide it with a proper nitch among its brethren, identifying "upper, lower, and middle" what-have-you as its temporal location. Although it is not discussed in the text, the graphs and charts make it clear that the stages are derived from "type sites," and many of the zones by specific "type fossils." The method of choosing these sites is made clear by discussion of individual locations and their data, as is the ability to change the location of THE site as needed. The authors also show clearly in these charts where globally derived and ocean-terrestrial zones are believed to overlap so that causation can be discussed. That's a lot of information for a student, information not often easily found in other texts but very important in understanding the literature. This is probably one of the few books on paleontology I've read where the charts and graphs are truly an integral part of the learning process and definitely NOT to be neglected by the student. Also for the student--and the interested general reader--the extinction literature is very well presented. The authors provide a very comprehensive discussion of events during each episode of proposed or possible extinction, referring to the pertinent literature world wide. This is significant, because to confirm a "massive" extinction requires world wide research. Events in narrow segments of the globe can always have been "local." The water column is presented from top to bottom, including information about in-fauna, which makes the discussions about causation of extinction very clear for the reader. It offers the student a window on the thought processes of research in extinction, on insights from technology, and on the causes of disagreement. One of the most significant, though passive, instructions the student receives by reading this text is the very objective, balance, and neutral approach to assessing the work of others--with one exception early in the book. The various differing views, even of the authors, are presented in a clear manner with the authors' "take" on things generally reserved for the end of the section. Their point of view is documented and discussed, and where they have nothing more to add than the rest of their colleagues, they say so plainly. At no time in the book is the student imposed upon with a biased, one-sided view of the knowledge of the field. Can't ask for more than that. Research methods are also presented. In particular Hallam and Wignall note that the extinction scientists can't make blind assumptions about data set. In particular they discusse some of the critics of Sepkowski and Raup's theories and data. Authors appealed to findings of two specific faunal types, namely fish and echinoderms, but failed to notice that the particular choice of these animals distorted their own results by virtue of the resistance to extinction in the former case and poor representation in the geological record in the second case. Issues like the effect of differential preservation are not always obvious unless the reader does research of a similar kind himself and then, quite obviously, not always then. Certainly the student planning a research project for a degree program would be wise to read the first few chapters of the book to see what pitfalls they need to avoid. In general the text covers the "Big Five" extinctions and discusses some of the smaller ones in as thorough a manner as is possible in the limited number of pages. It certainly gives the student a better comprehension of what constitutes a mass extinction, how such an event is represented in the faunal record, how the data available can be statistically manipulated to produce a clearer understanding of what was occurring at the time, and how all of this information can help identify possible causes for the phenomenon of mass extinction itself. In general a superb presentation of the field, but not really for the uninitiated.

A Good Overview of Mass Extinctions:
'Mass Extinctions and Their Aftermath' by A. Hallam and P. B. Wignall is a good overview of the episodes of mass extinctions in the history of life. Beginning with a brief primer on the 'anatomy' and significance of mass extinctions, the book covers both major and minor mass extinction events chronologically and succintly, with plenty of references. It summarizes the plausible cause (or causes) of these extinctions, as well as post-extinction recoveries. All-in-all, a slim volume which, through its compartmentalized structure and excellent reference database, provides a stepping stone to more specialized work.