Articoli di riviste: "Paleontology – british columbia – yoho national park"

1

Hong, Won S., John Snyder, David Trexler e Peter Kuchar. "A list of Hepaticae from Yoho National Park, British Columbia, Canada". Evansia 5, n. 1 (1988): 6–13. http://dx.doi.org/10.5962/p.345866.

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2

Reasoner, Mel A., e Michael Hickman. "Late Quaternary environmental change in the Lake O'Hara region, Yoho National Park, British Columbia". Palaeogeography, Palaeoclimatology, Palaeoecology 72 (gennaio 1989): 291–316. http://dx.doi.org/10.1016/0031-0182(89)90149-1.

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3

Yochelson, Ellis L., e Mikhail A. Fedonkin. "The type specimens (Middle Cambrian) of the trace fossil Archaeonossa Fenton and Fenton". Canadian Journal of Earth Sciences 34, n. 9 (1 settembre 1997): 1210–19. http://dx.doi.org/10.1139/e17-097.

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The original description of Archaeonossa, from beds considered Early Cambrian but now dated as early Middle Cambrian, included at least two unrelated forms of trace fossils. The ichnogenus and the type ichnospecies are redefined, a lectotype is designated, and the type material is reiilustrated, along with topotype material from Yoho National Park, British Columbia. Although this trace fossil was originally attributed to movement by a gastropod, it is concluded, on the basis of restudy, that the type occurrence should not be used as evidence of activity by Gastropoda.

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4

Legg, David. "Multi-Segmented Arthropods from the Middle Cambrian of British Columbia (Canada)". Journal of Paleontology 87, n. 3 (maggio 2013): 493–501. http://dx.doi.org/10.1666/12-112.1.

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A new arthropod, Kootenichela deppi n. gen. n. sp., is described from the Stanley Glacier exposure of the middle Cambrian (Series 3, Stage 5) Stephen Formation in Kootenay National Park (British Columbia, Canada). This taxon possesses a number of primitive arthropod features such as an elongate, homonomous trunk (consisting of at least 29 segments), poorly sclerotised trunk appendages, and large pedunculate eyes associated with an anterior (ocular) sclerite. The cephalon encompasses a possible antenna-like appendage and enlarged raptorial appendages with a bipartite peduncle and three spinose distal podomeres, indicative of megacheiran (“great-appendage” arthropod) affinities. The relationships of megacheirans are controversial, with them generally considered as either stem-euarthropods or a paraphyletic stem-lineage of chelicerates. An extensive cladistic analysis resolved Kootenichela as sister-taxon to the enigmatic Worthenella cambria from the middle Cambrian (Series 3, Stage 5), Burgess Shale Formation in Yoho National Park (British Columbia), which is herein reinterpreted as a megacheiran arthropod. Based on their sister-group relationship, both taxa were placed in the new family Kootenichelidae, to which Pseudoiulia from the Chengjiang biota is also tentatively assigned. All of these taxa possess an elongate, multi-segmented body and subtriangular exopods. This family occupies a basal position within a paraphyletic Megacheira, the immediate outgroup of Euarthropoda (crown-group arthropods). The resultant topology indicates that analyses that have resolved megacheirans as stem-chelicerates have done so because they have rooted on inappropriate taxa, e.g., trilobitomorphs and marrellomorphs.

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Nanglu, Karma, Jean-Bernard Caron e Robert R. Gaines. "The Burgess Shale paleocommunity with new insights from Marble Canyon, British Columbia". Paleobiology 46, n. 1 (febbraio 2020): 58–81. http://dx.doi.org/10.1017/pab.2019.42.

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AbstractThe middle (Wuliuan Stage) Cambrian Burgess Shale is famous for its exceptional preservation of diverse and abundant soft-bodied animals through the “thick” Stephen Formation. However, with the exception of the Walcott Quarry (Fossil Ridge) and the stratigraphically older Tulip Beds (Mount Stephen), which are both in Yoho National Park (British Columbia), quantitative assessments of the Burgess Shale have remained limited. Here we first provide a detailed quantitative overview of the diversity and structure of the Marble Canyon Burgess Shale locality based on 16,438 specimens. Located 40 km southeast of the Walcott Quarry in Kootenay National Park (British Columbia), Marble Canyon represents the youngest site of the “thick” Stephen Formation. We then combine paleoecological data sets from Marble Canyon, Walcott Quarry, Tulip Beds, and Raymond Quarry, which lies approximately 20 m directly above the Walcott Quarry, to yield a combined species abundance data set of 77,179 specimens encompassing 234 species-level taxa. Marble Canyon shows significant temporal changes in both taxonomic and ecological groups, suggesting periods of stasis followed by rapid turnover patterns at local and short temporal scales. At wider geographic and temporal scales, the different Burgess Shale sites occupy distinct areas in multivariate space. Overall, this suggests that the Burgess Shale paleocommunity is far patchier than previously thought and varies at both local and regional scales through the “thick” Stephen Formation. This underscores that our understanding of Cambrian diversity and ecological networks, particularly in early animal ecosystems, remains limited and highly dependent on new discoveries.

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Reasoner, Mel A., e Raymond E. Healy. "Identification and significance of tephras encountered in a core from Mary Lake, Yoho National Park, British Columbia". Canadian Journal of Earth Sciences 23, n. 12 (1 dicembre 1986): 1991–99. http://dx.doi.org/10.1139/e86-184.

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Mary Lake is a small, subalpine lake located proximal (<3 km) to the Continental Divide near Lake O'Hara in Yoho National Park, British Columbia. A 1.25 m core recovered from surficial bottom sediments was found to contain both Bridge River tephra (2350 years BP) and Mazama tephra (6800 years BP). Identification of the tephras was initially based on distinctive colour, texture, phenocryst assemblages, and glass shard habits and was confirmed by electron microprobe analysis of the constituent glass shards. The microprobe technique employed backscattered and secondary electron imagery and both energy dispersive and wavelength dispersive analyses.Mean annual sedimentation rates calculated from tephra depths in the Mary Lake core were found to be of the order of 0.15 mm/year for the post-Bridge River time period and 0.02 mm/year for the Mazama – Bridge River interval. The preservation of Mazama tephra in Mary Lake lacustrine sediments indicates that deglaciation had proceeded upvalley from the Mary Lake basin prior to 6800 years BP, and consequently, moraine systems exposed downvalley are pre-Mazama in age.

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LoDuca, Steven T., Jean-Bernard Caron, James D. Schiffbauer, Shuhai Xiao e Anthony Kramer. "A reexamination of Yuknessia from the Cambrian of British Columbia and Utah". Journal of Paleontology 89, n. 1 (gennaio 2015): 82–95. http://dx.doi.org/10.1017/jpa.2014.7.

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AbstractTo investigate the phylogenetic affinity of Yuknessia simplex Walcott, 1919, scanning electron microscopy was applied to the Burgess Shale (Cambrian Series 3, Stage 5) type material and to new material from the Trilobite Beds (Yoho National Park) and specimens from the Cambrian of Utah. On the basis of fine-scale details observed using this approach, including banding structure interpreted as fusellae, Yuknessia Walcott, 1919 is transferred from the algae, where it resided for nearly a century, to the extant taxon Pterobranchia (Phylum Hemichordata). Considered as such, Yuknessia specimens from the Trilobite Beds and Spence Formation (Utah) are amongst the oldest known colonial pterobranchs. Two morphs regarded herein as two different species are recognized from the Trilobite Beds based on tubarium morphology. Yuknessia simplex has slender erect tubes whereas Yuknessia stephenensis n. sp., which is also known in Utah, has more robust erect tubes. The two paratypes of Y. simplex designated by Walcott (1919) are formally removed from Yuknessia and are reinterpreted respectively as an indeterminate alga and Dalyia racemata Walcott, 1919, a putative red alga.

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8

Rogerson, R. J. "Measured Re-advance of a Debris-covered Glacier Terminus in the President Range, Yoho National Park, British Columbia, Canada". Journal of Glaciology 31, n. 107 (1985): 13–17. http://dx.doi.org/10.1017/s0022143000004937.

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AbstractMeasurements made at the terminus of Emerald Glacier in the Rocky Mountains of Canada indicate terminal re-advance in the order of one to two metres per year sustained since 1978 at least. Re-advance is maximum along that part of the terminus which is heavily covered with supraglacial debris, where ice remains in contact with a push-moraine all summer. Re-advance may represent fluctuations of a small, responsive ice mass, or the early effects of recent climatic deterioration.

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9

Rogerson, R. J. "Measured Re-advance of a Debris-covered Glacier Terminus in the President Range, Yoho National Park, British Columbia, Canada". Journal of Glaciology 31, n. 107 (1985): 13–17. http://dx.doi.org/10.3189/s0022143000004937.

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AbstractMeasurements made at the terminus of Emerald Glacier in the Rocky Mountains of Canada indicate terminal re-advance in the order of one to two metres per year sustained since 1978 at least. Re-advance is maximum along that part of the terminus which is heavily covered with supraglacial debris, where ice remains in contact with a push-moraine all summer. Re-advance may represent fluctuations of a small, responsive ice mass, or the early effects of recent climatic deterioration.

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10

O’Brien, Lorna J., e Jean-Bernard Caron. "Paleocommunity Analysis of the Burgess Shale Tulip Beds, Mount Stephen, British Columbia: Comparison with the Walcott Quarry and Implications for Community Variation in the Burgess Shale". Paleobiology 42, n. 1 (6 novembre 2015): 27–53. http://dx.doi.org/10.1017/pab.2015.17.

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AbstractThe Tulip Beds locality on Mount Stephen (Yoho National Park, British Columbia) yields one of the most abundant and diverse (~10,000 specimens in 110 taxa) Burgess Shale fossil assemblages in the Canadian Rockies. Detailed semi quantitative and quantitative analyses of this assemblage suggest strong similarities with the Walcott Quarry on Fossil Ridge. Both assemblages are dominated by epibenthic, sessile, and suspension feeding taxa, mostly represented by arthropods and sponges and have comparable diversity patterns, despite sharing only about half the genera. However, the Tulip Beds has a higher relative abundance of suspension feeders and taxa of unknown affinity compared to the Walcott Quarry. These biotic variations are probably largely attributable to ecological and evolutionary differences between the two temporally distinct communities that adapted to similar, but not identical, environmental settings. For instance, the Tulip Beds is farther away from the Cathedral Escarpment than the Walcott Quarry. The Tulip Beds and Walcott Quarry assemblages are more similar to each other than either one is to the assemblages of the Chengjiang biota, although the relative diversity of major taxonomic groups and ecological patterns are similar in all assemblages. The conserved diversity patterns and ecological structures among sites suggest that the ecological composition of Cambrian Burgess Shale-type communities was relatively stable across wide geographic and temporal scales.

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Zhao, Fangchen, Jean-Bernard Caron, David J. Bottjer, Shixue Hu, Zongjun Yin e Maoyan Zhu. "Diversity and species abundance patterns of the Early Cambrian (Series 2, Stage 3) Chengjiang Biota from China". Paleobiology 40, n. 1 (2014): 50–69. http://dx.doi.org/10.1666/12056.

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Lagerstättenfrom the Precambrian–Cambrian transition have traditionally been a relatively untapped resource for understanding the paleoecology of the “Cambrian explosion.” This quantitative paleoecological study is based on 10,238 fossil specimens belonging to 100 animal species, 11 phyla, and 15 ecological categories from the lower Cambrian (Series 2, Stage 3) Chengjiang biota (Mafang locality near Haikou, Yunnan Province, China). Fossils were systematically collected within a 2.5-meter-thick sequence divided into ten stratigraphic intervals. Each interval represents an induced time-averaged assemblage of various event (obrution) beds of unknown duration. Overall, the different fossil assemblages are taxonomically and ecologically similar, suggesting the presence of a single community type recurring throughout the Mafang section. The Mafang community is dominated by epibenthic vagile hunters or scavengers, sessile suspension feeders, and infaunal vagile hunters or scavengers represented primarily by arthropods, brachiopods, and priapulids, respectively. Most species have low abundance and low occurrence frequencies, whereas a few species are numerically abundant and occur frequently. Overall, in structure and ecology the Mafang community is comparable to the Middle Cambrian (Series 3, Stage 5) Burgess Shale biota (Walcott Quarry, Yoho National Park, British Columbia, Canada). This suggests that, despite variations in species identity within taxonomic and ecological groups, the structure and ecology of Cambrian Burgess Shale-type communities remained relatively stable until at least the Middle Cambrian (Series 3, Stage 5) in subtidal to relatively deep-water offshore settings in siliciclastic soft-substrate environments.

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12

Hickman, Michael, e Mel A. Reasoner. "Diatom responses to late Quaternary vegetation and climate change, and to deposition of two tephras in an alpine and a sub-alpine lake in Yoho National Park, British Columbia". Journal of Paleolimnology 11, n. 2 (1994): 173–88. http://dx.doi.org/10.1007/bf00686864.

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13

Beaudoin, Alwynne B., e Mel A. Reasoner. "Evaluation of differential pollen deposition and pollen focussing from three Holocene intervals in sediments from Lake O'Hara, Yoho National Park, British Columbia, Canada: intra-lake variability in pollen percentages, concentrations and influx". Review of Palaeobotany and Palynology 75, n. 1-2 (dicembre 1992): 103–31. http://dx.doi.org/10.1016/0034-6667(92)90152-7.

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D. M. "S. Conway Morris & H. B. Whittington 1985. Fossils of the Burgess Shale. A National Treasure in Yoho National Park, British Columbia. Geological Survey of Canada, Miscellaneous Report no. 43. v + 31 pp. Ottawa: Geological Survey of Canada. Price Canada: C$5.75; other countries: C$6.90 (paperback). ISBN 0 660 11901 3." Geological Magazine 123, n. 6 (novembre 1986): 711. http://dx.doi.org/10.1017/s001675680002433x.

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15

Danner, W. R. "How Old Is That Mountain? A Visitor's Guide to the Geology of Banff and Yoho National Parks.: By Dr. Chris Yorath. Harbour Publishing, P.O. Box 219, Madeira Park, British Columbia V0N 2H0. Paperback, Color and black-and-white photos, diagrams and maps, 6'' x 9'', 143 pages. $24.95, revised edition 2006, ISBN 1 55017 390 1." Canadian Mineralogist 44, n. 6 (1 dicembre 2006): 1564. http://dx.doi.org/10.2113/gscanmin.44.6.1564.

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16

Taerum, Robert L. "Evidence for pre-Cenozoic extension in the eastern Main Ranges of the southern Canadian Rockies". Geosphere, 8 marzo 2022. http://dx.doi.org/10.1130/ges02347.1.

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The eastern Main Ranges of the southern Canadian Rocky Mountain thrust-and-fold belt include a network of normal faults (the result of apparent extensional episodes) that occur within a contractional orogen. The origin, timing, and nature of these normal faults remain unresolved. A widely accepted explanation proposes that the normal faults developed as a consequence of postcontractional transtension that occurred west of the Rocky Mountain Trench during the Paleogene Period. Detailed field mapping of deformation in the vicinity of several normal faults has provided evidence that the normal fault surfaces and adjacent strata underwent deformation during a contractional episode after the normal faults had formed. Within the study area, located in the upper Kicking Horse region of Yoho National Park, British Columbia, Canada, and within the larger region of the Rocky Mountain belt, the network of normal faults is proposed to have developed as a consequence of rifting that separated pericratonic terranes from North America and produced the Slide Mountain Ocean during the Carboniferous and Permian Periods. Overprinting from more recent tectonic episodes has obscured most of these inferred extensional faults throughout the North American Cordillera. Within the study area, however, the Cretaceous to Paleogene contraction carried the normal faults to their present location over unattenuated continental crust, without significant overprinting. This preservation of the network of normal faults allows for investigation of the relationships among the fault surfaces and the strata adjacent to each fault.

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