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This chapter discusses the author's own personal experience in witnessing the growth of Precambrian paleobiology. It relates how the assumptions accepted by early workers influenced the development of this science and how and by whom breakthrough advances were brought to the fore in the mid-1960s. This chapter discusses the pioneering works of John William Dawson, Charles Doolittle Walcott, and Albert Charles Seward. It also narrates the story of the gradual expansion of the fossil record over the past several decades, including the discovery of microfossils dating some 3.5 billion years old.

This chapter examines modern approaches to perhaps the oldest problem in paleontology, specifically the perceived incompleteness of the fossil record. It focuses on the larger-scale patterns that may be gleaned from the fossil record such as global diversification and mass extinction. This chapter evaluates recent approaches in molecular phylogenetics and statistical tests of paleontological sampling error and suggests that while accurately interpreting the fossil record still presents many challenges, the future prospects for paleobiology are quite good.

Paleontological and geological evidence played significantly important roles in establishing Charles Darwin's theory of evolution, which combined descent with modification. The historical evidence of the fossil record enabled Darwin to argue for the temporal evolutionary succession of past forms. In the first and successive editions of Origin, Darwin discussed the significance of fossil succession, in this edition it is clearly implied that paleontology formed a major pillar of his argument for evolution. Yet in what appears in retrospect a profound irony, even as Darwin elevated the significance of the evidentiary contribution of fossils, he also had a major hand in condemning paleontology. One of his greatest anxieties was that the “incompleteness” of the fossil record would be used to criticize his theory: that the apparent “gaps” in fossil succession could be cited as negative evidence, at the very least, for his proposal that all organisms have descended by minute and gradual modifications from a common ancestor. Darwin worried that at worst the record's imperfection would be used to argue for the kind of spontaneous, “special” creation of organic forms promoted by theologically-oriented naturalists whose theories he hoped to obviate.

Fossils are critically important for evolutionary studies as they provide the link between geological ages and the phylogeny of life. The Pancrustacea are an incredibly diverse clade, representing over 800,000 described extant species, encompassing a variety of familiar and unfamiliar forms, such as ostracods, tongue worms, crabs, lobsters, shrimps, copepods, barnacles, branchiopods, remipedes, and insects. Having colonized nearly every environment on Earth, from hydrothermal vents to terrestrial habitats, they have a diverse fossil record dating back to the Cambrian (540–485 Ma). The quality of the fossil record of each clade is variable and related to their lifestyle (e.g., free-living versus parasitic, benthic versus pelagic) and the degree of mineralization of their cuticle. We review the systematics, morphology, preservation, and paleoecology of pancrustacean fossils; each major clade is discussed in turn, and, where possible, fossil systematics are compared with more recent data from molecular phylogenetics. We show that the three epic clades of the Pancrustacea—Allotriocarida, Multicrustacea, and Oligostraca—all have Cambrian roots, but the diversification of those clades did not take place until the Middle and Late Paleozoic. We also address the potential affinities of three “problematic” clades: euthycarcinoids, thylacocephalans, and cyclids. We conclude by assessing the future of pancrustacean paleobiology, discussing new morphological imaging techniques and further integration with growing molecular phylogenetic data.

This chapter explores the taxic approach as a dominant perspective in paleobiology, and its contribution to the solidification of what came to be known as the Chicago School of analytical paleontology. It also represented the culmination of a long tradition in paleobiology—of drawing statistical interpretations of patterns in the history of life from an otherwise imperfect fossil record. This approach, in many ways, represents the paleobiological tradition in the second half of the twentieth century. The term “taxic paleontology” is defined as follows: “Paleontologists have always had the option of looking at the fossil record, in either or both of two ways—first, distributions in space and time of discrete taxa, which differ among themselves to a greater or lesser extent, and second, distributions in space and time of different states of morphological character assumed to be evolving.” Punctuated equilibria and the MBL model helped prepare the path for a taxic view. In each case, species are considered to be discrete entities with clearly demarcated births and deaths. This was not, however, the essence of taxic paleobiology. The taxic approach is also implicitly an ecological view, since it understands evolution to consist “essentially of the origin, maintenance, and degradation of diversity”. This view is inspired by the mathematical modeling approach of the MacArthur-Wilson insular model of biogeography. However, it developed its own uniquely paleobiological perspective with the advent of massive fossil databases.

This chapter discusses the following topics: the extinction of most life on earth; the fossil record and what it tells us about evolution; the relation between paleontology and the biological disciplines of development; parallels between paleontological and developmental transformations; that ontogeny does not simply recapitulate phylogeny; evolution of ontogenies; ontogeny and the conditions of existence; the relation between ontogeny and phylogeny; and ontogeny and the reconstruction of the tree of life.

Due to its extensive deep-time history encompassing almost 600 million years, the fossil record offers important insights into changing biodiversity in marine ecosystems, inluding rapid diversification during the radiation of metazoans in the Ediacaran and the Cambrian explosion. This chapter examines three key biodiversity changes in history: the Ediacaran radiation of large multicellular eukaryotes, the Cambrian radiation of complex bilaterian-grade animals, and the end-Permian mass extinction. It discusses changes in biodiversity and their relation to various factors involved in ecosystem functioning such as bioturbation (biogenic mixing depth), functional diversity, and productivity. It also considers the link between species richness and functional diversity, the productivity-biodiversity relationship, and environmental changes during the late Paleozoic to early Mesozoic.

This chapter examines punctuated equilibrium and compares it to the idea of community evolution that emerged from ecological study of the fossil record. It identifies what is believed to be the weakness of the punctuated equilibrium theory and argues that community evolution is based on a more reliable empirical foundation. This chapter explains how punctuated equilibrium fails the sampling test because it assumes that there are only two rate modes characterizing species-level evolution and that newly evolved allopatric taxa have the inherent capability of reinvading the region of the parent species' environment.

Paleobiology transformed from a loose movement with a fairly uncoordinated set of goals to a bonafide sub-discipline with an active institutional and intellectual agenda. The dynamics of this shift are complex, and involve theoretical, institutional, and pedagogical factors. One of the striking features of the history of paleobiology is the extent to which the movement came to be so closely associated with a few signature theories. Over the time paleobiology emerged as a fairly casual label used to describe a broad approach to an array of questions surrounding the application of fossil data to problems in evolutionary biology. There is a set of practices that can be associated with this approach (such as quantitative analysis, modeling, and ecological/biogeographical theory), there is no unifying theoretical basis for paleobiology, nor did the term “paleobiology” have a distinct disciplinary identity within paleontology. However, paleobiology became closely associated with a prominent theory—known as the theory of punctuated equilibria—and the study of macroevolution as a dominant conceptual framework. Punctuated equilibria have two important roles. First, its invocation of Wrightian stochasticity provided inspiration for a number of studies that more deeply probed the influence of random or nondirectional elements in evolution as seen in the fossil record. Second, it acted as a model of a typoe of paleontology that could break the grip of Darwin's dilemma and could offer a route to bringing paleontology into the mainstream of evolutionary biology.

This chapter describes a particular model of the fossil record that helps quantify the impact of stratigraphic architecture on the occurrence of fossils. The basic features of the fossil record that are influenced by the stratigraphic record are also discussed. Ecology and evolution play an important role in controlling the occurrence of taxa in the fossil record, but this record is fundamentally altered by stratigraphic architecture. Paleobiologic interpretations that rely on the stratigraphic occurrence of fossils must acknowledge the effects of stratigraphic architecture and deal with them. The advent of sequence stratigraphy, coupled with ecological gradient models, allows for the understanding and quantifying the structure and completeness of the fossil record. These models reveal not only ways in which the fossil record may be controlled by processes of sediment deposition, but also clues to recognizing those effects and strategies for overcoming them.

This chapter describes the growth and transformation of theoretical paleontology over the years. There has been recently a major transformation in paleontological approaches to evolutionary theory and the fossil record. This shift involved several distinct but related aspects. First, paleontologists began to actively assess the institutional status of their discipline—asking whether paleontology “belonged,” for example, with geology, or with biology, or rather whether it constituted an independent discipline on its own. Second, paleontologists began more and more to connect explicitly their work with the evolutionary agenda of the modern synthesis, and to publish in outlets that were read by biologists and geneticists. Third, and perhaps most significantly, paleontology became quantitative. Earlier quantitative methods (measurements and statistical analysis) were absent from the work of paleontology, resulting in synthetic questions about the fossil record of a quantitative rigor and sophistication not previously seen in paleontological literature.

The study and modeling of the history of diversity over time motivated a methodological question: how reliable is the fossil record, and how can that reliability be tested? These problems became the core of analytical paleobiology, and represented a continuation and a consolidation of the themes examined thus far in the history of paleobiology. Ultimately, this focus led paleobiologists to ground-breaking quantitative studies of the interplay of rates of origination and extinction of taxa through time, the role of background and mass extinctions in the history of life, the survivorship of individual taxa, and the modeling of historical patterns of diversity. These questions became the central components of an emerging paleobiological theory of macroevolution. This chapter explores the early stages of this development in paleobiology by examining the emergence of a new, clearly-articulated agenda: the often-expressed desire to construct a “nomothetic paleontology.” This phrase originated first in an important sequence of papers that sought to develop a stochastic, equilibrial simulation of evolutionary dynamics over time—what came to be known as the MBL model—and quickly became a rallying cry for the new approach to paleobiology. The term “nomothetic” essentially means “law-producing”. The chapter also outlined some of the essential features of this approach.

This chapter delves into the development of the theory of punctuated equilibria, widely known as “punk eek.” Punctuated equilibria integrates the idea of the origin of species through geographic isolation with the near-universal pattern of stasis. Stasis refers to the event in which most species do not seem to exhibit any form of change for the duration of their lives, often over millions of years. Despite the difficulty of tracing steady, gradual modification of an ancestral species into an undoubted descendant, new species still unexpectedly show up in the fossil record. The imagery caught in punctuated equilibria thus appears to be relatively rapid bursts of evolution interrupting longer periods of non-change of species.

Mammalian life history and physiology are correlated with several anatomical features, some of which are recorded as fossils. They show us that diagnostic mammalian features did not originate simultaneously, and that some evolved convergently in lineages which eventually became extinct. This chapter discusses developmental evolution at the root of the living mammalian diversity; the hominid fossil record; what is special about human development; Neanderthal babies and growth; and the timing of life history events.

Bonebeds are remarkable features of the vertebrate fossil record that can embody ancient environmental catastrophes and, thus, reveal some of the most dramatic aspects of past ecosystems. They can also serve as less sensational but equally informative gauges of sedimentary dynamics and biological recycling. Regardless of their particular mode(s) of origin, bonebeds, in their many forms, provide exceptional opportunities to investigate a variety of paleobiological and geological questions. This chapter proposes a system for the categorization and analysis of bonebeds analogous to the genetic classification scheme proposed by Kidwell et al. (1986) for marine macrobenthic concentrations. It explains how vertebrate hardparts accumulate and discusses biogenic concentrations, physical concentrations, fluvial channels, strandlines, bioclasts, obrution concentration, and sediment deposition.

The evolution of the Crustacea following their origins in the Cambrian is outlined, with an overview of their paleontological history and global distributions into modern times. Major recent developments in arthropod evolution include recognition that Hexapoda is nested within Crustacea. Perspectives also changed during the last decades of the 20th century on the form of the crustacean ancestor, from being a long-bodied, serially homonomous form (like a remipede or cephalocarid) to a short-bodied, possibly ostracod-like form similar to Cambrian stem and crown group fossil forms. These changes have come through a shift to formal methods of phylogenetic analysis combined with the much larger volume of both morphological and molecular data now available. The most extensive current phylogenies typically recover the short-bodied Oligostraca (containing ostracods and a few minor groups) as basal crustaceans; Malacostraca and Maxillopoda are high in the tree; and Cephalocarida and Remipedia are derived forms as sister to Branchiopoda and Hexapoda, respectively. Each of these major groups can be understood through variations in tagmatization (differentiation of body segments into regions). The early crustacean fossil record (especially the Ordovician) is dominated by ostracods. Malacostracans, although having Cambrian origins, did not significantly radiate until the Mesozoic. Eumalacostraca continued to actively radiate in the Cenozoic and are now the most ubiquitous and morphologically disparate crustaceans. The processes driving crustacean evolution remain to be fully evaluated. Contingency and external factors are undoubtedly important, but most deep lineages of the Crustacea show pervasive macroevolutionary trends toward increasing tagmatization. These trends are apparently driven, meaning the formation of new body plans is not merely a contingent outcome—intrinsic factors may contribute to increasing tagmatization. Further data are required from ontogeny and developmental genetics, paleontology, and phylogenetics in order to better understand how crustaceans have evolved.