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12 results on '"Bourne, G.R."'

7. Complex Dental Structure and Wear Biomechanics in Hadrosaurid Dinosaurs

Author

Erickson, G.M., Krick, B.A., Hamilton, M., Bourne, G.R., Norell, M.A., Lilleodden, E., and Sawyer, W.G.

Subjects
ddc:620.11
Abstract

Mammalian grinding dentitions are composed of four major tissues that wear differentially, creating coarse surfaces for pulverizing tough plants and liberating nutrients. Although such dentition evolved repeatedly in mammals (such as horses, bison, and elephants), a similar innovation occurred much earlier (~85 million years ago) within the duck-billed dinosaur group Hadrosauridae, fueling their 35-million-year occupation of Laurasian megaherbivorous niches. How this complexity was achieved is unknown, as reptilian teeth are generally two-tissue structures presumably lacking biomechanical attributes for grinding. Here we show that hadrosaurids broke from the primitive reptilian archetype and evolved a six-tissue dental composition that is among the most sophisticated known. Three-dimensional wear models incorporating fossilized wear properties reveal how these tissues interacted for grinding and ecological specialization.

Published
2012

8. A new species of Colostethus (Anura, Dendrobatidae) from French Guiana with a redescription of Colostethus beebei (Noble, 1923) from its type locality

Author

Kok, Ph.J.R., MacCulloch, R.D., Gaucher, P., Poelman, E.H., Bourne, G.R., Lathrop, A., Lenglet, G.L., Kok, Ph.J.R., MacCulloch, R.D., Gaucher, P., Poelman, E.H., Bourne, G.R., Lathrop, A., and Lenglet, G.L.

Abstract

A new species of Colostethus (Anura, Dendrobatidae) from French Guiana with a redescription of Colostethus beebei (Noble, 1923) from its type locality, a new species of Colostethus, long mistaken for Colostethus beebei, is described from French Guiana. The New species can be distinguished from congeners by absence of median lingual process, first finger longer than second, third finger not distinctly swollen in males, differences in tadpole morphology, coloration, and pattern (e.g. absence of dorsolateral stripe) bioacoustics, and reproducitve behavior. A complete redescription of Colotethus beebei, plus its tadpole and call is provided on the basis of recently collected topotypic specimens. The range of C. beebei is restricted to the Kaieteur plateau, Pakaraima, Guyana

Published
2006

9. Movement, home range and core area use patterns in two populations of North American river otters (Lontra canadensis)

Author

Boege-Tobin, D.D., Tang-Martinez, Z., and Bourne, G.R.

Subjects
Otters -- Physiological aspects, Otters -- Behavior, Home range -- Research, Animal locomotion -- Research, Zoology and wildlife conservation
Abstract

North American river otters (Lontra canadensis) were radio-implanted and subsequently tracked for 11-20 months at two locations in Missouri. Home range and core area use dynamics for these two populations were evaluated using three different spatial analysis packages. Individual animal movement patterns were examined using the ArcView GIS Animal Movement Extension and were evaluated spatially and temporally, from both a daily and seasonal perspective. Comparisons between the two sites and among individuals of different age and sex classes will be reported.

Published
2003

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