The term 'biodiversity' is a simple contraction of 'biological diversity', and at first sight the concept is simple too: biodiversity is the sum total of all biotic variation from the level of genes to ecosystems. The challenge comes in measuring such a broad concept in ways that are useful. We show that, although biodiversity can never be fully captured by a single number, study of particular facets has led to rapid, exciting and sometimes alarming discoveries. Phylogenetic and temporal analyses are shedding light on the ecological and evolutionary processes that have shaped current biodiversity. There is no doubt that humans are now destroying this diversity at an alarming rate. A vital question now being tackled is how badly this loss affects ecosystem functioning. Although current research efforts are impressive, they are tiny in comparison to the amount of unknown diversity and the urgency and importance of the task.

Getting the measure of biodiversity

The evolutionary dynamics underlying the latitudinal gradient in biodiversity have been controversial for over a century. Using a spatially explicit approach that incorporates not only origination and extinction but immigration, a global analysis of genera and subgenera of marine bivalves over the past 11 million years supports an "out of the tropics" model, in which taxa preferentially originate in the tropics and expand toward the poles without losing their tropical presence. The tropics are thus both a cradle and a museum of biodiversity, contrary to the conceptual dichotomy dominant since 1974; a tropical diversity crisis would thus have profound evolutionary effects at all latitudes.

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Out of the Tropics: Evolutionary Dynamics of the Latitudinal Diversity Gradient

Historical biogeography has been characterized by a large diversity of methods and unresolved debates about which processes, such as dispersal or vicariance, are most important for explaining distributions. A new R package, BioGeoBEARS, implements many models in a common likelihood framework, so that standard statistical model selection procedures can be applied to let the data choose the best model. Available models include a likelihood version of DIVA (“DIVALIKE”), LAGRANGE’s DEC model, and BAYAREA, as well as “+J” versions of these models which include founder-event speciation, an important process left out of most inference methods. I use BioGeoBEARS on a large sample of island and non-island clades (including two fossil clades) to show that founder-event speciation is a crucial process in almost every clade, and that most published datasets reject the non-J models currently in widespread use. BioGeoBEARS is open-source and freely available for installation at the Comprehensive R Archive Network at http://CRAN.R-project.org/package=BioGeoBEARS. A step-by-step tutorial is available at http://phylo.wikidot.com/biogeobears.

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Probabilistic historical biogeography: new models for founder-event speciation, imperfect detection, and fossils allow improved accuracy and model-testing

Taphonomy plays diverse roles in paleobiology. These include assessing sample quality relevant to ecologic, biogeographic, and evolutionary questions, diagnosing the roles of various taphonomic agents, processes and circumstances in generating the sedimentary and fossil records, and reconstructing the dynamics of organic recycling over time as a part of Earth history. Major advances over the past 15 years have occurred in understanding (1) the controls on preservation, especially the ecology and biogeochemistry of soft-tissue preservation, and the dominance of bi- ological versus physical agents in the destruction of remains from all major taxonomic groups (plants, invertebrates, vertebrates); (2) scales of spatial and temporal resolution, particularly the relatively minor role of out-of-habitat transport contrasted with the major effects of time-averaging; (3) quantitative compositional fidelity; that is, the degree to which different types of assemblages reflect the species composition and abundance of source faunas and floras; and (4) large-scale var- iations through time in preservational regimes (megabiases), caused by the evolution of new bod- yplans and behavioral capabilities, and by broad-scale changes in climate, tectonics, and geochem- istry of Earth surface systems. Paleobiological questions regarding major trends in biodiversity, major extinctions and recoveries, timing of cladogenesis and rates of evolution, and the role of environmental forcing in evolution all entail issues appropriate for taphonomic analysis, and a wide range of strategies are being developed to minimize the impact of sample incompleteness and bias. These include taphonomically robust metrics of paleontologic patterns, gap analysis, equal- izing samples via rarefaction, inferences about preservation probability, isotaphonomic compari- sons, taphonomic control taxa, and modeling of artificial fossil assemblages based on modern an- alogues. All of this work is yielding a more quantitative assessment of both the positive and neg- ative aspects of paleobiological samples. Comparisons and syntheses of patterns across major groups and over a wider range of temporal and spatial scales present a challenging and exciting agenda for taphonomy in the coming decades.

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Taphonomy and paleobiology

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Paleosols in clastic sedimentary rocks: their geologic applications

Introduction - adequacy versus incompleteness, Stephen K. Donovan and Christopher R.C. Paul adequacy, completeness and the fossil record, Christopher R.C. Paul determining stratugraphics ranges, Charles R. Marshall resolution of the fossil record - the fidelity of preservation, David M. Martill the completeness of the Pleistocene fossil record - implications for stratigraphic adequacy, Benjamin J. Greenstein et al an overview of the completeness of the fossil record, Christopher R.C. Paul and Stephen K. Donovan fossil solids and completeness of the rock and fossil records, Gregory J. Retallack phylogenetic analyses and the quality of the fossil record, Peter J. Wagner "taxonomic barriers" and other distortions within the fossil record, Carl F. Koch patterns of occurrence of benthic Foraminifera in time and space, Stephen J. Culver and Martin A. Buzas the fossil record of cheilostome bryozoa in the Neogene and Quaternay of tropical America - adequacy for phylogenetic and evolutionary studies, Alan H. Cheetham and Jeremy B.C. Jackson the fossil record of bivalue molluscs, Elizabeth M. Harper the quality of the fossil record of the vertebrates, Michael J. Benton.

The adequacy of the fossil record

Morphology and function of dichoporite pore-structures in cystoids

SUMMARY Little is known about ammonites as prey. Two papers report single British examples of fatally bitten ammonites. Globally, two previous papers describe damage similar to that recorded herein. Nevertheless, in the Charmouth Mudstone Formation of the lower Lias Group at Lyme Regis, up to 20% of small ammonites ( Promicroceras , Xipheroceras , Cymbites , Arnioceras , Asteroceras , Caenisites , Eoderoceras and Paltechioceras ?) show ventral damage at the rear of the body chamber that is far too consistent in morphology and position to result from accidents. Single pieces of shell, which extend almost symmetrically on either side and reach the umbilical seam on one side, are missing. Midpoint of the damage lies at 80% of the body chamber length back from the aperture, with a coefficient of variation of 10%. Damage at this position would sever attachment muscles and facilitate removal of the body from the aperture. Lack of shell chips preserved adjacent to damaged ammonites precludes scavenging or post-burial crushing as causes of the damage. Ammonites were caught in the water column, manipulated into a horizontal position and bitten at a precise point. The most likely predator was an active swimmer, able to hold and manipulate a smooth, possibly slippery, ammonite shell. The slightly asymmetrical damage is consistent with bites made by robust, parrot-like, cephalopod jaws (rhyncholites), which are known from the same stratigraphic interval. Ammonites are less likely predators than teuthoids. Belemnites, lacking suckers, are discounted. Lobster-like crustaceans are unlikely to have been able to catch, hold and manipulate shells. Lack of tooth marks precludes most vertebrate predators. These bite marks are referred to Bicrescomanducator rolli Donovan, Paul, Andrew & Howe igen. et isp. nov.

Christopher R. C. Paul

Papers

The adequacy of the fossil record

Morphology and function of dichoporite pore-structures in cystoids

Fatally bitten ammonites from the lower Lias Group (Lower Jurassic) of Lyme Regis, Dorset

British ordovician cystoids

The British Silurian cystoids