The scientific understanding of arthropod phylogeny and evolution has changed significantly in recent decades. One of the most momentous alterations involved crustaceans, which are not a monophyletc group, but are part of a larger group along with insects: Pancrustacea. The old ideas surrounding crustacean evolution have served scientists well for many years; it is now time to turn toward new research by embracing the results derived from investigations conducted largely within this century. For example, new definitions have arisen from sources across several fields of study, and Frederick R. Schram and Stefan Koenemann have created a book that explores paleobiodiversity and the diversity of modern body plans. Developments within ontogenetic studies continue to generate remarkable insights into crustaceomorph evolution in regard to patterns of embryology and a revolution in the application of development genetics. Phylogeny techniques of analysis and new sources of data derived from molecular sequencing and genetic studies have forced scientists to consider new hypotheses concerning the interrelationships of all the pancrustaceans, both the crustaceomorphs and Hexapoda. Yet, some fossil groups still remain enigmatic (Thylacocephala). Despite this, research into fossils (even if incompletely understood) fills in gaps of our knowledge of paleobiodiversity, and it's useful for many things, including analyzing the origin and early evolution of Hexapoda. Evolution and Phylogeny of Pancrustacea demonstrates the use of multiple alternative hypotheses and other techniques through the well-executed presentation of diverse data sources involving Pancrustacea. Readers are left with clues to great mysteries, including the possible pathways of evolution within marine arthropods.

This is the eighth volume of a ten-volume series on The Natural History of the Crustacea. The volume examines Evolution and Biogeography, and the first part of this volume is entirely dedicated to the explanation of the origins and successful establishment of the Crustacea in the oceans. In the second part of the book, the biogeography of the Crustacea is explored in order to infer how they conquered different biomes globally while adapting to a wide range of aquatic and terrestrial conditions. The final section examines more general patterns and processes, and the chapters offer useful insight into the future of crustaceans.

"As a young and impetuous gradate student, I thought that sorting out the phylogeny of crustaceans would simply take but a little time and concerted effort to eventually reveal the truth. Everyone could then agree and further research would proceed apace. How naïve I was. First of all, I had never heard of Kurt Gödel's incompleteness theorems and hence the impossibility of achieving such an end. But even so, what progress we might have made turned out to take longer than anyone could have imagined, and the effort would be immense involving many people and a number of laboratories-and that task still continues. What no one could foresee in the 1960s was that the focus of everyone's attentions would completely transform. Traditional pure anatomy would be augmented with more sophisticated developmental genetic work. Concurrent with that effort molecular sequencing would become a remarkably effective tool. And with these new sources of data, the concept of "crustaceans" would yield to a new construct-Pancrustacea-within which the arthropods that we referred to by the name of "Crustacea" became a series of monophyletic smaller groups that mark a paraphyletic transition from a mandibulate ancestor all the way up to a crown group that few in the 1960s expected-Hexapoda emerged within the pancrustaceans"--

Compared to other arthropods, crustaceans are characterized by an unparalleled disparity of body plans. Traditionally, the specialization of arthropod segments and appendages into distinct body regions has served as a convenient basis for higher classification; however, many relationships within the phylum Arthropoda still remain controversial.

This is the eighth volume of a ten-volume series on The Natural History of the Crustacea. The volume examines Evolution and Biogeography, and the first part of this volume is entirely dedicated to the explanation of the origins and successful establishment of the Crustacea in the oceans. In the second part of the book, the biogeography of the Crustacea is explored in order to infer how they conquered different biomes globally while adapting to a wide range of aquatic and terrestrial conditions. The final section examines more general patterns and processes, and the chapters offer useful insight into the future of crustaceans.

More than two thirds of all living organisms described to date belong to the phylum Arthropoda. But their diversity, as measured in terms of species number, is also accompanied by an amazing disparity in terms of body form, developmental processes, and adaptations to every inhabitable place on Earth, from the deepest marine abysses to the earth surface and the air. The Arthropoda also include one of the most fashionable and extensively studied of all model organisms, the fruit-fly, whose name is not only linked forever to Mendelian and population genetics, but has more recently come back to centre stage as one of the most important and more extensively investigated models in developmental genetics. This approach has completely changed our appreciation of some of the most characteristic traits of arthropods as are the origin and evolution of segments, their regional and individual specialization, and the origin and evolution of the appendages. At approximately the same time as developmental genetics was eventually turning into the major agent in the birth of evolutionary developmental biology (evo-devo), molecular phylogenetics was challenging the traditional views on arthropod phylogeny, including the relationships among the four major groups: insects, crustaceans, myriapods, and chelicerates. In the meantime, palaeontology was revealing an amazing number of extinct forms that on the one side have contributed to a radical revisitation of arthropod phylogeny, but on the other have provided evidence of a previously unexpected disparity of arthropod and arthropod-like forms that often challenge a clear-cut delimitation of the phylum.