Microscopic Effects of Predator Digestion on the Surfaces of Bones and Teeth

Concentrations of small fossil mammals are frequently encountered in Cenozoic deposits, but the causes for such accumulations have seldom been determined. In many cases the tooth, jaw, and limb fragments appear to be well-preserved under light microscopy, and it is difficult to differentiate damage due to predator digestion from breakage and abrasion due to physical agents. In order to find more specific evidence of predator digestion, we used a scanning electron microscope (SEM) to examine the surface microstructure of bones and teeth consumed by Bubo virginianus (great horned owl) and Canis latrans (coyote), which prey upon similar species. Effects of digestion were found on all the digested bones and teeth examined. The effects on bone include distinctive sets of pits and fissures, dissolution, and physical polishing. The pits and fissures are apparently caused by solution that commences in canals beneath the surf ace of the bone. The most conspicuous effects on teeth are island-like pillars of dentin surrounded by deep solution fissures. The effects of digestion by coyote and owl are fundamentally the same but differ in degree of development. Bone digested by the owl shows a greater degree of polishing and rounding of edges but has less extensive fissuring. Wide variation in the degree of surface damage occurs in bones digested by the coyote, even within a single fecal pellet

Laser-induced fluorescence determination of temperatures in low pressure flames

Rensberger KJ, Jeffries JB, Copeland RA, Kohse-Höinghaus K, Wise ML, Crosley DR. Laser-induced fluorescence determination of temperatures in low pressure flames. Applied Optics. 1989;28(17):3556-3566.Spatially resolved temperatures in a variety of low pressure flames of hydrogen and hydrocarbons burning with oxygen and nitrous oxide are determined from OH, NH, CH, and CN laser-induced fluorescence rotational excitation spectra. Systematic errors arising from spectral bias, time delay, and temporal sampling gate of the fluorescence detector are considered. In addition, we evaluate the errors arising from the influences of the optical depth and the rotational level dependence of the fluorescence quantum yield for each radical. These systematic errors cannot be determined through goodness-of-fit criteria and they are much larger than the statistical precision of the measurement. The severity of these problems is different for each radical; careful attention to the experimental design details for each species is necessary to obtain accurate LIF temperature measurements

Au coeur de la vie. Au royaume de la cellule vivante

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Early adaptive radiations of Aplodontoidea (Rodentia, Mammalia) on the Holarctic region: systematics, and phylogenetic and paleobiogeographic implications

International audienceThe Aplodontoidea, now restricted to only oneNorth American species (Aplodontia rufa), have shown awide Holarctic extension since the Upper Eocene. As theirfossil record is poor, their phylogenetic relationships andthe origins of their successive radiations remain unclear.We perform here phylogenetic analyses, primarily based ondental evidence (94 dental of 97 characters), restricted toPaleogene and early Miocene taxa (46 taxa) in order toavoid biases introduced by substantially derived (divergent)taxa. We confirm the inclusion of some problematicgenera such as Cedromus or Douglassciurus withinSciuroidea rather than in Aplodontoidea. Ephemeromysand Lophallomys appear as the most basal members of theAplodontoidea, and Epeiromys is the closest outgroup ofthe Sciuroidea-Aplodontoidea clade. The relationshipsamong the ‘‘prosciurines’’ remain unclear, with paraphyleticgenera such as Prosciurus and Haplomys. Theirdiagnoses are reevaluated and a new genus is described.The Aplodontidae, including the clade of the latter, andHaplomys liolophus display a dichotomy betweenAnsomyinae and Aplodontinae, the two crown groups. Thefirst clade formed by the European species argoviensis anddescendens (referred to a new genus) can be proposed as asister group of the species of Ansomys. The second branchof the dichotomy includes the European Plesispermophilusand Sciurodon as basal groups. The species of Parallomysdo not form a clade, and the genus appears paraphyletic.The last dichotomy separates the Allomys clade from the‘meniscomyine’ clade. Comparisons of the selected speciesallow consideration of their patterns of dental evolution(e.g. enlargement of P4, development of a metaloph—protoloph disto-mesial connection, of crescentic shape inmain cusps and ectoloph, of a buccal protruding compressedmesostyle, of a metastylid crest or an anterior spurof the hypoconid, etc.). The split between sciuroids andaplodontoids occurred in North America, and then aplodontoidsdispersed rapidly throughout the whole Holarcticregion. The first aplodontid adaptive radiation took placeeither in North America or in Asia. Periodic exchangesoccurred between Europe, Asia and North America, andthe last radiations (meniscomyines) were restricted inNorth America