Middle Triassic-Anisian-ammonoids from northeastern British Columbia and Ellesmere Island

1969 ◽  
Author(s):  
F H Mclearn
Keyword(s):  
British Columbia ◽  
Middle Triassic ◽  
Ellesmere Island

Helmolepis cyphognathus, sp. nov., a new platysiagid actinopterygian from the Lower Triassic Sulphur Mountain Formation (British Columbia, Canada)

2005 ◽  
Vol 42 (1) ◽  
pp. 25-36 ◽  
Author(s):  
Andrew G Neuman ◽  
Raoul J Mutter
Keyword(s):  
British Columbia ◽  
New Species ◽  
Central Europe ◽  
Middle Triassic ◽  
Lower Triassic ◽  
Western Canada ◽  
Early Triassic ◽  
East Greenland ◽  
The Family ◽  
A New Species

A new species of stem actinopterygian, Helmolepis cyphognatus sp. nov., is reported from the Lower Triassic Sulphur Mountain Formation of western Canada (probably Smithian). This taxon differs from the only other known Early Triassic platysiagid, H. gracilis from the Lower Triassic Wordie Creek Formation of East Greenland (Griesbachian), in counts of branchiostegal rays, shape of the maxilla, shape (and possibly counts) of extrascapulars, and the size ratio of major opercular bones. In spite of their overall unfavorable preservation, the numerous available specimens amend our knowledge of the little known genus Helmolepis considerably: it has become evident that the morphology of Helmolepis cyphognatus sp. nov. comes closest to Platysiagum minus (Middle Triassic Besano Formation of central Europe). This study suggests placement of the two genera in the family Platysiagidae. Investigation of this new species also shows certain features of the cheek and the caudal fin are more primitive than previously believed, whereas the snout region is probably derived but of yet uncertain affinities in Helmolepis.

Freboldia carinii sp. nov. from the Middle Triassic Brembana Valley (Esino Limestone, Southern Alps, Italy) – possibly the oldest known holoplanktonic gastropod

2020 ◽  
Vol 298 (1) ◽  
pp. 9-15
Author(s):  
Vittorio Pieroni ◽  
Alexander Nützel
Keyword(s):  
Life Style ◽  
Thin Shell ◽  
Type Species ◽  
Middle Triassic ◽  
Canadian Arctic ◽  
Southern Alps ◽  
Early Jurassic ◽  
Ellesmere Island ◽  
Gastropod Species ◽  
Mass Occurrence

A monospecific mass occurrence of the new gastropod species Freboldia carinii sp. nov. is described from the Middle Triassic Esino Limestone of the Brembana Valley, Southern Alps, Italy. It is the second species assigned to the genus Freboldia that was initially described from the Early Jurassic of Ellesmere Island, Canadian Arctic. This gastropod is unusual in being planispiral and inflated with a nearly bilateral symmetrical shape and in having a very thin shell. Like the Canadian type species of Freboldia, the new Triassic species is interpreted as a possibly holoplanktonic gastropod. If true, it would be the oldest known example of this life style in Gastropoda.

On the presence ofMixosaurus(Ichthyopterygia: Reptilia) in the Middle Triassic of Nevada

1990 ◽  
Vol 64 (1) ◽  
pp. 161-164 ◽  
Author(s):  
P. Martin Sander ◽  
Hugo Bucher
Keyword(s):  
British Columbia ◽  
North America ◽  
Middle Triassic ◽  
Lower Triassic ◽  
High Arctic ◽  
Western Tethys ◽  
History Of ◽  
Northwestern North America

The small ichthyosaurMixosaurusis the most widely distributed ichthyosaur. It is known from Lower Triassic rocks of British Columbia, Canada (Callaway and Brinkman, 1989), and Middle Triassic rocks of northwestern North America (Alaska, British Columbia), China, Timor, the western Tethys (Switzerland, Italy, Turkey), the Germanic Triassic, and the high Arctic (Spitsbergen, Exmouth Island) (Mazin, 1986; Callaway and Brinkman, 1989; Callaway and Massare, 1989). The presence ofMixosaurusin one of the richest ichthyosaur provinces, the Middle Triassic of Nevada (Merriam, 1908), has been difficult to establish. The history of this problem is very colorful and is the topic of this note together with the description of a new specimen from the Nevada Middle Triassic.

Geology of the Cadwallader Group and the Intermontane–Insular superterrane boundary, southwestern British Columbia

1987 ◽  
Vol 24 (11) ◽  
pp. 2279-2291 ◽  
Author(s):  
Margaret E. Rusmore
Keyword(s):  
British Columbia ◽  
Middle Jurassic ◽  
Tectonic Evolution ◽  
Middle Triassic ◽  
Upper Triassic ◽  
Tectonic Block ◽  
Volcanic Arc ◽  
Arc Volcanism ◽  
Clastic Rocks ◽  
Tectonic Settings

Several lower Mesozoic, fault-bounded units separate the Intermontane and Insular superterranes in southwestern British Columbia. Detailed study of one of these Mesozoic units, the Cadwallader Group, helps clarify the boundary between the superterranes and establish the tectonic evolution of southwestern British Columbia. The Cadwallader Group is the oldest unit in an Upper Triassic through Middle Jurassic volcanic and sedimentary tectono-stratigraphic terrane. Two formations, the Pioneer and the Hurley, compose the Cadwallader Group; the previously recognized Noel Formation is no longer considered valid. The Pioneer Formation contains pillow basalt, flows, and basalt breccia. Siltstone, sandstone, conglomerate, and minor amounts of limestone megabreccia and basalt belonging to the Hurley Formation conformably overlie the Pioneer. The Hurley spans latest Carnian or earliest Norian to middle Norian time. Two episodes of deformation affected the Cadwallader, and a thrust fault separates the group from slightly younger clastic rocks of the Tyaughton Group. Similarities in clastic rocks indicate the Tyaughton was deposited on the Cadwallader; together the units form the Cadwallader terrane. Basalts and clastic rocks in the terrane record deposition in or near a Carnian to earliest Norian volcanic arc. Volcanism waned later in the Norian, but presence of the arc is preserved in the clastic rocks.Oceanic rocks of the Middle Triassic to Middle Jurassic Bridge River terrane became juxtaposed with the Cadwallader terrane in Middle Jurassic time, after which the terranes functioned as a single tectonic block. Contrasting volcanic histories suggest that the Cadwallader terrane was not accreted to the Intermontane superterrane until Middle Jurassic or Early Cretaceous time, although the similar tectonic settings of Stikinia and the Cadwallader terrane allow a common earlier history. The Cadwallader terrane is not part of either the Alexander terrane or Wrangellia, and so the inboard margin of the Insular superterrane must lie west of the Cadwallader terrane.

Permian Sponges from Northwestern British Columbia

1973 ◽  
Vol 10 (11) ◽  
pp. 1600-1606 ◽  
Author(s):  
J. Keith Rigby
Keyword(s):  
British Columbia ◽  
Northwest Territories ◽  
Ellesmere Island ◽  
Upper Paleozoic

Three lithistid sponges, including Scheiia tuberosa Tschernyschew and Stepanov, 1916, Haplistion aff. H. aeluroglossa Finks, 1960, and a chiastoclonellid sponge (which is not generically identifiable because of fragmentary preservation) are reported from limestone of the Cache Creek Group. Fossils were collected from Artinskian(?) beds, near Dewar Peak in the McConnell Creek area, at the southeastern end of the Sustut Basin in northwestern British Columbia. These are the first reported lithistid sponges from the Upper Paleozoic section in that region. Related sponges have been described from Texas and Ellesmere Island, Northwest Territories.

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