Evolution of the subgenus Cyphelophorus (Genus Helophorus, Hydrophilidae, Coleoptera): description of two new fossil species and discussion of Helophorus tuberculatus Gyll.

1976 ◽  
Vol 54 (5) ◽  
pp. 652-673 ◽  
Author(s):  
John V. Matthews Jr.
Keyword(s):  
Intraspecific Variation ◽  
Canadian Arctic ◽  
Morphological Features ◽  
Canadian Arctic Archipelago ◽  
Evolutionary Trends ◽  
Fossil Species ◽  
The North ◽  
Extant Species ◽  
Late Tertiary ◽  
North American Arctic

Exposures of late Tertiary sediments in the North American Arctic contain well-preserved fossils of Coleoptera (beetles). Two sites, Lava Camp in western Alaska and locality 2-73 on Meighen Island (Canadian Arctic Archipelago), have yielded fragments referable to two fossil species of the helophoran subgenus Cyphelophorus (Hydrophilidae). The only extant species in the subgenus, Helophorus tuberculatus Gyll., is characterized by a distinctive array of elytral tubercles, the intraspecific variation of which is documented here as an aid for distinguishing H. tuberculatus from the two fossil species.The two fossil species are obviously related to H. tuberculatus and probably represent sequential species in the lineage leading to H. tuberculatus. If so, they provide information on evolutionary trends within the Cyphelophorus lineage, and when examined in the light of the morphological features of species in other Helophorus subgenera, show that the tuberculate elytron seen in H. tuberculatus is probably a derived character that developed by modification of an elytron initially having raised alternate interstices.

Coleoptera fossils: their potential value for dating and correlation of late Cenozoic sediments

1977 ◽  
Vol 14 (10) ◽  
pp. 2339-2347 ◽  
Author(s):  
John V. Matthews Jr.
Keyword(s):  
Canadian Arctic ◽  
Canadian Arctic Archipelago ◽  
Fossil Plants ◽  
Late Cenozoic ◽  
Extinct Species ◽  
Extant Species ◽  
Late Tertiary ◽  
Climatic History ◽  
Cenozoic Sediments ◽  
Insect Fossils

Coleoptera (beetle) fossils play an important role in paleoecological research, but as yet have contributed little information bearing on dating and correlation. The reason for this is that most Quaternary fossils represent extant species, precluding the evolutionary approach to dating, while the rarity and poor preservation of Tertiary beetle fossils, many of which are from extinct species, seriously limit their application to stratigraphic studies.Tertiary beetle fossils recently discovered in Arctic Canada and Alaska are both well preserved and abundant. Most of them represent extinct species that are closely related to living forms, hence they have potential stratigraphic value. In one case treated herein comparison of fossils of an Alaskan Tertiary species with those of a related species from the Beaufort Formation on Meighen Island (Canadian Arctic Archipelago) implies that the latter sediments were deposited less than 5.7 Ma ago. However, this conclusion requires testing because it is at odds with the date on Meighen Island exposures reached by study of fossil plants. I submit that further study of the insect fossils from the Beaufort Formation and other late Tertiary sites will help resolve such problems of dating and correlation.Quaternary beetle fossils have stratigraphic value even though fragments of that age represent for the most part only existing species. For example, it has been shown that late Pleistocene fossils of stenothermal Coleoptera species can provide a sensitive record of climatic change, and thus such fossils may be used for site to site correlation in areas where climatic history is well documented. In exceptional cases beetle fossils appear to provide a more accurate basis for correlation than even fossil pollen.

New evidence from the western Canadian Arctic Archipelago for the resubmergence of Bering Strait

2008 ◽  
Vol 70 (1) ◽  
pp. 60-67 ◽  
Author(s):  
John H. England ◽  
Mark F.A. Furze
Keyword(s):  
Arctic Ocean ◽  
North Atlantic ◽  
Canadian Arctic ◽  
Laptev Sea ◽  
Canadian Arctic Archipelago ◽  
Bering Strait ◽  
The North ◽  
Banks Island ◽  
The North Atlantic ◽  
The Laptev Sea

AbstractWidespread molluscan samples were collected from raised marine sediments to date the last retreat of the NW Laurentide Ice Sheet from the western Canadian Arctic Archipelago. At the head of Mercy Bay, northern Banks Island, deglacial mud at the modern coast contains Hiatella arctica and Portlandia arctica bivalves, as well as Cyrtodaria kurriana, previously unreported for this area. Multiple H. arctica and C. kurriana valves from this site yield a mean age of 11.5 14C ka BP (with 740 yr marine reservoir correction). The occurrence of C. kurriana, a low Arctic taxon, raises questions concerning its origin, because evidence is currently lacking for a molluscan refugium in the Arctic Ocean during the last glacial maximum. Elsewhere, the oldest late glacial age available on C. kurriana comes from the Laptev Sea where it is < 10.3 14C ka BP and attributed to a North Atlantic source. This is 2000 cal yr younger than the Mercy Bay samples reported here, making the Laptev Sea, ~ 3000 km to the west, an unlikely source. An alternate route from the North Atlantic into the Canadian Arctic Archipelago was precluded by coalescent Laurentide, Innuitian and Greenland ice east of Banks Island until ~ 10 14C ka BP. We conclude that the presence of C. kurriana on northern Banks Island records migration from the North Pacific. This requires the resubmergence of Bering Strait by 11.5 14C ka BP, extending previous age determinations on the reconnection of the Pacific and Arctic oceans by up to 1000 yr. This renewed ingress of Pacific water likely played an important role in re-establishing Arctic Ocean surface currents, including the evacuation of thick multi-year sea ice into the North Atlantic prior to the Younger Dryas geochron.

Magnetostratigraphy of Quaternary and late Tertiary sediments on Banks Island, Canadian Arctic Archipelago

1998 ◽  
Vol 35 (2) ◽  
pp. 147-161 ◽  
Author(s):  
R W Barendregt ◽  
J -S Vincent ◽  
E Irving ◽  
J Baker
Keyword(s):  
Climate Changes ◽  
Direct Evidence ◽  
Canadian Arctic ◽  
Canadian Arctic Archipelago ◽  
Banks Island ◽  
Pleistocene Climate ◽  
Late Tertiary ◽  
Normal Polarity ◽  
Continental Glaciation ◽  
Geocentric Axial Dipole

Sediments approximately 50 m thick from Banks Island (Canadian Arctic Archipelago) contain one of the longest terrestrial records of Pleistocene climate changes in North America. Samples have been obtained from 126 horizons distributed among four localitites, of which 116 horizons yielded acceptable paleomagnetic data. In sediments of the Matuyama Reversed Zone, there are recorded at least two and possibly as many as five full continental glaciations, two interglacial intervals, and a nonglacial interval at the beginning which is considered preglacial. Subzones attributable to the Olduvai and Jaramillo are present within the Matuyama Reversed Zone. The Brunhes Normal Zone records three full continental glaciations and three interglaciations. The Brunhes-Matuyama boundary occurs within interglacial deposits. The preglacial Worth Point Formation records a climate milder than today, and cooler than that of the late Tertiary. Based on floral, faunal, stratigraphic, and paleomagnetic constraints, a normal polarity sequence in the Worth Point Formation is assigned to the Olduvai normal polarity subzone (1.95-1.77 Ma). The earliest direct evidence of glaciation on Banks Island occurs in sediments that postdate the Worth Point Formation ( <<1.77 Ma). Consequently, in the western Canadian Arctic, the first continental glaciation postdated the first glaciation in the Canadian Cordillera (2.6 Ma) by at least a million years. The overall mean direction of the Quaternary geomagnetic field in Banks Island does not differ significantly from the geocentric axial dipole field, and these sediments contain no inclination error.

Late Cenozoic paleomagnetic record of Duck Hawk Bluffs, Banks Island, Canadian Arctic Archipelago

1990 ◽  
Vol 27 (1) ◽  
pp. 124-130 ◽  
Author(s):  
R. W. Barendregt ◽  
Jean-Serge Vincent
Keyword(s):  
Canadian Arctic ◽  
Unconsolidated Sediments ◽  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Gradual Change ◽  
Canadian Arctic Archipelago ◽  
Late Cenozoic ◽  
Precise Position ◽  
Banks Island ◽  
Late Tertiary

Detailed paleomagnetic investigations have been completed on unconsolidated sediments from Duck Hawk Bluffs on Banks Island, in the Canadian Arctic Archipelago, that record some of the oldest late Cenozoic glacial and nonglacial events in Canada. The preglacial Worth Point Formation, the overlying Duck Hawk Bluffs Formation, including marine and glacial deposits laid down during the Banks Glaciation, and the lower part of the interglacial Morgan Bluffs Formation have magnetically reversed directions and therefore are of Matuyama age (>790 ka). Upper Morgan Bluffs Formation organic beds and deposits of the younger Thomsen Glaciation, Cape Collinson Interglaciation, and Amundsen Glaciation are normally magnetized and therefore of Brunhes age (<790 ka). The Brunhes–Matuyama boundary is recorded in the upper portion of the Morgan Bluffs Formation. Its precise position within the interglacial sequence can be identified, since the sediments document the gradual change from reversely inclined directions to normally inclined ones. These results confirm that the preglacial Worth Point Formation is at least Early Pleistocene in age and that the Banks Glaciation (the oldest and strongest continental glaciation recorded in the western Arctic) and a good part of the Morgan Bluffs Formation are of Early Pleistocene age. The study also documents a rare site in Canada where terrestrial sediments record the Brunhes–Matuyama transition and in doing so permits a precise correlation of part of the Banks Island stratigraphy with other key late Tertiary and Early to Middle Pleistocene arctic terrestrial and marine sequences.

Whole-rock Rb/Sr and zircon U/Pb ages of metamorphic rocks from northern Ellesmere Island, Canadian Arctic Archipelago. II. The Cape Columbia Complex

1976 ◽  
Vol 13 (6) ◽  
pp. 774-780 ◽  
Author(s):  
A. K. Sinha ◽  
Thomas Frisch
Keyword(s):  
North Atlantic ◽  
Age Groups ◽  
Canadian Arctic ◽  
Ellesmere Island ◽  
Metamorphic Rocks ◽  
Canadian Arctic Archipelago ◽  
Fold Belt ◽  
The North ◽  
The North Atlantic ◽  
North Atlantic Craton

Although not clearly separable on field and petrographic criteria, the gneisses of the Cape Columbia Complex, one of the two major crystalline terrains in the Northern Ellesmere Fold Belt, fall into two Rb/Sr age groups: nine samples define an isochron corresponding to an age of 1083 ± 18 m.y., Sr0 = 0.7057, while six samples show more scatter at 512 ± 90 m.y.,Sr0 = 0.7189. Zircons from two gneisses have 207Pb/206Pb, i.e. minimum, ages of 926 and 980 m.y. These data are interpreted as indicating that the rocks were recrystallized in the amphibolite facies about 1000 m.y. ago; little significance is attached to the younger Rb/Sr age. However, the possibility that the rocks are orthogneisses emplaced about 1000 m.y. ago and subsequently metamorphosed ~500–600 m.y. ago, cannot be excluded. In any event, the Cape Columbia Complex becomes the latest addition to the growing list of occurrences of 900–1200 m.y.-old ('Grenville-Sveco-Norwegian') rocks in the North Atlantic craton and environs.

Greenland and the Future

1980 ◽  
Vol 7 (4) ◽  
pp. 295-299
Author(s):  
Jørgen Taagholt
Keyword(s):  
North American ◽  
Canadian Arctic ◽  
Coastal Areas ◽  
Canadian Arctic Archipelago ◽  
Bering Strait ◽  
The South ◽  
The North ◽  
The Future ◽  
East And West

About 4,000 years ago the first Eskimo tribes reached Northern Greenland after a migration taking some thousands of years from Asia via the Bering Strait, then along the North American coastal areas and over the Canadian Arctic archipelago. They settled primarily in the northernmost part of Greenland, where archaeological finds are the basis of our knowledge of their life. Subsequent waves of immigration resulted in settlements to the south, along Greenland's east and west coasts (Fig. 1).

scholarly journals Two unusual new species of Caleremaeus (Acari: Oribatida) from eastern North America, with redescription of C. retractus and reevaluation of the genus

Acarologia ◽  
2020 ◽  
Vol 60 (2) ◽  
pp. 398-448
Author(s):  
Roy A. Norton ◽  
Valerie M. Behan-Pelletier
Keyword(s):  
New Species ◽  
Oribatid Mite ◽  
Adult Size ◽  
Transverse Ridge ◽  
Fossil Species ◽  
The North ◽  
Extant Species ◽  
The Family ◽  
Eastern Usa

The oribatid mite genus Caleremaeus (Caleremaeidae) is widely distributed in the northern hemisphere but has been represented by only three extant and one fossil species. We redescribe the North American C. retractus (Banks, 1947) based on adults and nymphs; it is distinguishable from the European type species, C. monilipes (Michael, 1882) by its smaller adult size and minor differences in cuticular structure, and by the elongated, tapered form of seta h1 in nymphs. Two new species are proposed: C. nasutus n. sp. from forest soil in Alabama is unique in having adults with a large anterior rostral lobe (juveniles unknown) bearing lamellar setae; the arboreal C. arboricolus n. sp. from eastern USA and Canada is unique among described extant species in having adults with femoral saccules, a transverse ridge bearing lamellar setae and relatively large notogastral setae, and juveniles with a bothridial seta similar to that of the adult. Based on all available data, Caleremaeus is redescribed and considered the sole genus in Caleremaeidae. The higher classification of the family is reviewed, and past placement in Ameroidea is rejected in favor of the monofamilial Caleremaeoidea.

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