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

Recent studies have shown that stable hydrogen isotope ratios (δD) in the tissues of animals often correlate with δD of local precipitation. Here we examined the relationship between δD in feathers and growing season precipitation for neotropical migrant songbirds breeding over a continent-wide isotopic gradient. δD values were determined on feathers of 140 individuals of 6 species of wild insectivorous forest songbirds (Setophaga ruticilla, Empidonax minimus, Vermivora peregrinus, Catharus ustulatus, Seiurus aurocapillus, Hylocichla mustelina) taken from 14 breeding locations across North America. The δD of feathers was strongly correlated with the δD of growing season precipitation at breeding sites across North America. As feather hydrogen is metabolically inert after growth, this relationship was then used to assess the breeding origins of wintering migrants. Deuterium values of feathers from 64 individuals representing 5 species of migrants (Helmitheros vermivorus, Wilsonia citrina, Hylocichla mustelina, Dumetella carolinensis, Seirus aurocapillus) at a wintering site in Guatemala were consistent with those predicted from the known breeding ranges of these species. This study demonstrates hydrogen isotopes may become a powerful tool for linking breeding and wintering grounds of neotropical migrant songbirds, as well as other migratory species moving between isotopically distinct regions.

Linking breeding and wintering grounds of neotropical migrant songbirds using stable hydrogen isotopic analysis of feathers.

To determine whether stable isotopes can be used for identifying the geographic origins of migratory bird populations, we examined the isotopic composition of hydrogen (deuterium, δD), carbon (δ13C), and strontium (δ87Sr) in tissues of a migratory passerine, the black-throated blue warbler (Dendroica caerulescens), throughout its breeding range in eastern North America. δD and δ13C values in feathers, which are grown in the breeding area, varied systematically along a latitudinal gradient, being highest in samples from the southern end of the species’ breeding range in Georgia and lowest in southern Canada. In addition, δD decreased from east to west across the northern part of the breeding range, from New Brunswick to Michigan. δ87Sr ratios were highest in the Appalachian Mountains, and decreased towards the west. These patterns are consistent with geographical variation in the isotopic composition of the natural environment, i.e., with that of precipitation, plants, and soils for δD, δ13C, and δ87Sr, respectively. Preliminary analyses of the δD and δ13C composition of feathers collected from warblers in their Caribbean winter grounds indicate that these individuals were mostly from northern breeding populations. Furthermore, variances in isotope ratios in samples from local areas in winter tended to be larger than those in summer, suggesting that individuals from different breeding localities may mix in winter habitats. These isotope markers, therefore, have the potential for locating the breeding origins of migratory species on their winter areas, for quantifying the degree of mixing of breeding populations on migratory and wintering sites, and for documenting other aspects of the population structure migratory animals – information needed for studies of year-round ecology of these species as well as for their conservation. Combining information from several stable isotopes will help to increase the resolution for determining the geographic origins of individuals in such highly vagile populations.

The use of isotope tracers for identifying populations of migratory birds

A great tradition in macroevolution and systematics has been the ritual squabbling between palaeontologists and molecular biologists. But, because both sides were talking past each other, they could never agree. Practitioners in both fields should play to their strengths and work together: palaeontologists can provide minimum constraints on branching points in the Tree of Life with considerable precision, and estimate the extent of unrecorded prehistory. Molecular tree analysts have remarkable modelling tools in their armoury to convert multiple minimum age constraints into meaningful dated trees. As we discuss here, work should now focus on establishing reasonable, dated trees that satisfy rigorous assessment of the available fossils and careful consideration of molecular tree methods: rocks and clocks together are an unbeatable combination. Reliably dated trees provide, for the first time, the opportunity to explore wider questions in macroevolution.

Rocks and clocks: calibrating the Tree of Life using fossils and molecules

Isotopic Study of the Biology of Modern and Fossil Vertebrates

Fragments of the large euryptcrid Pterygotus , recently collected from the Devonian Campbellton Formation at Atholville, New Brunswick, are identified as belonging to P. anglicus Agassiz . The only previous Pterygotus specimens from this site, collected in 1881, were assigned to a new species P. atlanticus Clarke and Ruedemann, in 1912. Clarke and Ruedcmann's suggestion that P. atlanticus might turn out to be a small specimen of P. anglicus is supported by this new find. However, possible revision of P. atlanticus awaits the discovery of additional, more complete, material.

			RESUME
			On a determine que les fragments du grand eurypteride Pterygotus recemment recueillis dans la Formation devonienne de Campbellton a Atholville, Nouveau-Brunswick, appartenaient au P, anglicus Agassiz . Les seuls specimens anterieurs de Pterygotus de cet emplacement, preIeves en 1881, avaient ete attribues a une nouvelle espece, le P. atlanticus , par Clarke et Ruedemann, en 1912. Cette nouvelle decouverte appuie l’hypothese de Clarke et Ruedemann a l'effet que Ie P. atlanticus pourrait en realite constituer un petit specimen de P. anglicus . La revision possible de la nature du P. atlanticus necessitera neanmoins la decouverte de materiel supplementaire plus complet.
			
[Traduit par la redaction]

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Note on Pterygotus anglicus Agassiz (Eurypterida: Devonian) from the Campbellton Formation, New Brunswick

We document the occurrence of a marine bed, and its associated biota, in the Lower Pennsylvanian (Langsettian) Tynemouth Creek Formation of New Brunswick, and discuss its implications for paleogeography, stratigraphy, and paleoecology. This is only the second marine interval found in the entire Pennsylvanian fill of the Maritimes Basin of Canada, the other being recently found in the broadly same-age Joggins Formation of Nova Scotia. Evidence for the new marine transgression comprises an echinoderm-rich limestone that infills irregularities on a vertic paleosol surface within the distal facies of a syntectonic fluvial megafan formed under a seasonally dry tropical climate. Gray, platy ostracod-rich shales and wave-rippled sandstone beds that directly overlie the marine limestone contain trace fossils characteristic of the Mermia Ichnofacies, upright woody trees, and adpressed megafloras. This association represents bay-fills fringed by freshwater coastal forests dominated by pteridosperms, cordai...

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A marine incursion in the lower pennsylvanian tynemouth creek formation, canada: implications for paleogeography, stratigraphy and paleoecology

In 1842, on the fifth of April, Abraham Gesner opened the doors of his museum in Saint John, New Brunswick to the public. The museum displayed part of his collection of almost 4,000 specimens. His published catalogue included more than 1,200 rocks, minerals and fossils along with a smaller number of invertebrate and vertebrate animals and artefacts. It survives today as one of Canada’s oldest geological collections. This national treasure documents the earliest days of the study of the geological sciences in Canada including specimens from Gesner’s surveys of New Brunswick and Nova Scotia. Although Gesner’s collection moved through three institutions, it has remained partly intact and is accompanied by a catalogue of the museum’s contents. SOMMAIRE
 Le 5 avril 1842, Abraham Gesner ouvrait au public son musee a Saint-Jean, Nouveau-Brunswick. Le musee exposait alors une partie de sa collection de pres de 4 000 specimens. Le catalogue qu'il a publie alors comprenait plus de 1 200 roches, mineraux et fossiles ainsi qu'un nombre moindre de specimens de vertebres, d'invertebres et d'artefacts. Il a survecu jusqu'a nos jours et constitue l'une des plus anciennes collections geologiques au Canada. Ce tresor canadien qui temoigne des premieres etudes scientifiques de la geologie au Canada comprend des specimens tires de leves effectues par Gesner au Nouveau-Brunswick et en Nouvelle-Ecosse. Bien que la collection de Gesner ait ete deplacee dans trois institutions, elle demeure encore partiellement intacte et comporte un catalogue de ses specimens.

Gesner’s Museum of Natural History, An Early Canadian Geological Collection

Studies of Coleoptera remains from two late-glacial sites on Cape Breton Island, Nova Scotia, Canada, present a picture of the paleoenvironment and paleoclimate during the Allerod–Younger Dryas transition in the Maritimes region. They provide evidence for the Younger Dryas event in northeastern North America. Between 11 300 and 10 800 BP, the beetle assemblages at the Campbell site are typical of faunas of the modern middle to northern boreal forest. The West Mabou site contains beetle fossils younger than 10 900 BP, possibly as young as 10 500 BP, extending into the time period of the Younger Dryas, dated from 10 800 to 10 000 BP in the Maritimes. A "cold climate" indicator recognizable in the beetle fauna, Olophrum boreale, occurs in relative abundance and provides an interesting comparison with sites in Europe where the same northern boreo-montane species is evident at the beginning of the Younger Dryas.

Allerod - Younger Dryas Coleoptera from Western Cape Breton Island, Nova Scotia, Canada

Reply to comment on the paper by Davies et al. “Resolving MISS conceptions and misconceptions: A geological approach to sedimentary surface textures generated by microbial and abiotic processes” (Earth Science Reviews, 154 (2016), 210–246)

Randall F. Miller

Papers

Note on Pterygotus anglicus Agassiz (Eurypterida: Devonian) from the Campbellton Formation, New Brunswick

A marine incursion in the lower pennsylvanian tynemouth creek formation, canada: implications for paleogeography, stratigraphy and paleoecology

Gesner’s Museum of Natural History, An Early Canadian Geological Collection

Allerod - Younger Dryas Coleoptera from Western Cape Breton Island, Nova Scotia, Canada

Reply to comment on the paper by Davies et al. “Resolving MISS conceptions and misconceptions: A geological approach to sedimentary surface textures generated by microbial and abiotic processes” (Earth Science Reviews, 154 (2016), 210–246)