The influence of diet on the distribution of nitrogen isotopes in animals was investigated by analyzing animals grown in the laboratory on diets of constant nitrogen isotopic composition. 
The isotopic composition of the nitrogen in an animal reflects the nitrogen isotopic composition of its diet. The δ^(15)N values of the whole bodies of animals are usually more positive than those of their diets. Different individuals of a species raised on the same diet can have significantly different δ^(15)N values. The variability of the relationship between the δ^(15)N values of animals and their diets is greater for different species raised on the same diet than for the same species raised on different diets. Different tissues of mice are also enriched in ^(15)N relative to the diet, with the difference between the δ^(15)N values of a tissue and the diet depending on both the kind of tissue and the diet involved. The δ^(15)N values of collagen and chitin, biochemical components that are often preserved in fossil animal remains, are also related to the δ^(15)N value of the diet. 
The dependence of the δ^(15)N values of whole animals and their tissues and biochemical components on the δ^(15)N value of diet indicates that the isotopic composition of animal nitrogen can be used to obtain information about an animal's diet if its potential food sources had different δ^(15)N values. The nitrogen isotopic method of dietary analysis probably can be used to estimate the relative use of legumes vs non-legumes or of aquatic vs terrestrial organisms as food sources for extant and fossil animals. However, the method probably will not be applicable in those modern ecosystems in which the use of chemical fertilizers has influenced the distribution of nitrogen isotopes in food sources. 
The isotopic method of dietary analysis was used to reconstruct changes in the diet of the human population that occupied the Tehuacan Valley of Mexico over a 7000 yr span. Variations in the δ^(15)C and δ^(15)N values of bone collagen suggest that C_4 and/or CAM plants (presumably mostly corn) and legumes (presumably mostly beans) were introduced into the diet much earlier than suggested by conventional archaeological analysis.

Influence of Diet On the Distribtion of Nitrogen Isotopes in Animals

Past episodes of greenhouse warming provide insight into the coupling of climate and the carbon cycle and thus may help to predict the consequences of unabated carbon emissions in the future.

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An early Cenozoic perspective on greenhouse warming and carbon-cycle dynamics

Fire is a worldwide phenomenon that appears in the geological record soon after the appearance of terrestrial plants. Fire influences global ecosystem patterns and processes, including vegetation distribution and structure, the carbon cycle, and climate. Although humans and fire have always coexisted, our capacity to manage fire remains imperfect and may become more difficult in the future as climate change alters fire regimes. This risk is difficult to assess, however, because fires are still poorly represented in global models. Here, we discuss some of the most important issues involved in developing a better understanding of the role of fire in the Earth system.

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Fire in the Earth System

The second edition of The Biomarker Guide is a fully updated and expanded version of this essential reference. Now in two volumes, it provides a comprehensive account of the role that biomarker technology plays both in petroleum exploration and in understanding Earth history and processes. Biomarkers and Isotopes in the Environment and Human History details the origins of biomarkers and introduces basic chemical principles relevant to their study. It discusses analytical techniques, and applications of biomarkers to environmental and archaeological problems. The Biomarker Guide is an invaluable resource for geologists, petroleum geochemists, biogeochemists, environmental scientists and archaeologists.

The Biomarker Guide

Bones of recent mammals in the Amboseli Basin, southern Kenya, exhibit distinctive weathering characteristics that can be related to the time since death and to the local conditions of temperature, humidity and soil chemistry. A categorization of weathering characteristics into six stages, recognizable on descriptive criteria, provides a basis for investigation of weathering rates and processes. The time necessary to achieve each successive weathering stage has been calibrated using known-age carcasses. Most bones decompose beyond recognition in 10 to 15 yr. Bones of animals under 100 kg and juveniles appear to weather more rapidly than bones of large animals or adults. Small-scale rather than widespread environmental factors seem to have greatest influence on weathering characteristics and rates. Bone weathering is potentially valuable as evidence for the period of time represented in recent or fossil bone assemblages, in- cluding those on archeological sites, and may also be an important tool in censusing populations of animals in modern ecosystems.

Taphonomic and Ecologic Information Form Bone Weathering

The fossil floras described by Dieter Mai and Harald Walther are invaluable for understanding the past plant diversity in Europe, and provide important information on the occurrence of taxa in the fossil record that is critical for evolutionary studies. Among the taxa they recognized were seeds assigned to the extant genus Alpinia Roxb. (Zingiberaceae, Zingiberales). We reinvestigated 28 specimens that were assigned to Alpinia arnensis (Chandler) Mai, Alpinia cf. arnensis, and Alpinia bivascularis Mai from the Ypresian (lower Eocene) of the UK, upper Eocene of Germany, and lower Miocene of Germany using non-destructive synchrotron-based X-ray tomography to reveal internal anatomy. None of the samples studied show an anatomy consistent with extant Alpinia or even Zingiberales. The fossils lack the globose shape, often striate external surface, seed coat structure, operculum, and micropylar collar seen in all Alpinia, and lack the chalazal chamber seen in many Alpinia species. Two specimens from the lower Miocene of Germany showed the structure of fruits of Caricoidea Chandler (Cyperaceae) with a single-layered exocarp, thick mesocarp, and sclerified endocarp. The other specimens are recognized as Carpolithes albolutum nom. nov. (incertae sedis) from the Ypresian of the UK, C. phoenixnordensis sp. nov. (incertae sedis) from the upper Eocene of Germany, C. bivascularis comb. nov. (incertae sedis) from the lower Miocene of Germany as well as indeterminate tegmens from the lower Miocene of Germany. This reinvestigation demonstrates that there is, as yet, no confirmed fossil record for the extant genus Alpinia. Furthermore, at least four different taxa are recognized from what had been two extinct species, enhancing our understanding of these important European Cenozoic carpofloras.

Revision of putative Alpinia (Zingiberaceae) fossils from the Paleogene and Neogene of western Europe

Palaeobotany: On follicles and flowers

The recent article by Israde-Alcantara et al (1) outlined a wide array of purported impact proxies from a lacustrine paleo-record in Lake Cuitzeo, Mexico These findings were used to support the suggestion of a Younger Dryas (YD) impact event/s Although most of the purported impact proxies have been described in previous publications (2, 3), this new work extended the range of such markers to Mexico The article also allowed the proponents of the YD Impact Hypothesis [YDIH] to respond to the many critiques of the YDIH

Inconsistent redefining of the carbon spherule “impact” proxy

A colony of a fern, Lygodium hians E.Fournier (Schizaeales), studied on the southwest Pacific Island of New Caledonia, displays a growth form unusual for any member of this genus. Other living species of the genus Lygodium Sw. are characterized by twining fronds, with indefinite growth, which climb extensively on the support provided by other nearby vegetation. These fronds can arise from as early as the sporeling stage and fulfil both vegetative and reproductive functions, with spores produced in lateral sorophores in the upper parts of the fronds. By contrast, in L. hians, climbing fronds are only rarely produced and these carry terminal to subterminal sorophores. The main vegetative growth is of a low-growing (here termed ‘ground-clothing') frond-type, of definite, rather than indefinite, growth and of unusual dichotomous blade structure. This life form has survived, in this rare and little known remote species, under conditions of considerable ecological, as well as geographic, isolation in t...

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Margaret E. Collinson

Papers

Revision of putative Alpinia (Zingiberaceae) fossils from the Paleogene and Neogene of western Europe

Palaeobotany: On follicles and flowers

Inconsistent redefining of the carbon spherule “impact” proxy

Lygodium hians E.Fournier (Pteridophyta, Schizaeales) — an endemic unusual ground-clothing member of a modern climbing fern genus in New Caledonia

A record of fire through the Early Eocene