... of the Ptarmigan limestone to the Cathedral dolomite; the stratigraphic position of the Ross Lake ( Albertella ) shale on Mounts Bosworth and Assiniboine, and the Ogygopsis shale on Mount Stephen; and the position of the southern shores of the Cambrian sea on the north side of the Montana Island. The Mounts...

...C. A. Nelson Abstract The range of Ogygopsis, a trilobite genus known principally from the Canadian Rocky Mountains where it occurs through most of the Middle Cambrian succession, is here extended downward to the upper part of the Lower Cambrian. In the Inyo Mountains, California, and in western...

...Terence P Fletcher; Desmond H Collins Abstract The Burgess Shale has been an anomalous geologic unit ever since Walcott named it in 1911 as the geographic equivalent of the Ogygopsis Shale in the Middle Cambrian Stephen Formation of southeastern British Columbia, but it has never been recognized...

...H. J. Hofmann; R. L. Parsley Abstract Two specimens of the Middle Cambrian trilobite Ogygopsis klotzi (Rominger) from the Stephen Formation, Mount Stephen, British Columbia, bear imprints of what appear to be antennae protruding from the anterior of the cephalon; they seem to originate beneath...

... lower Cambrian) carbonate ramp strata of the Sekwi Formation and overlying Miaolingian (traditional middle Cambrian) deep-water, calciturbiditic strata of the Hess River Formation has been regarded as diachronous. This important transition, which marks the onset of long-lived, deep-water conditions...

...Wayne G. Powell; Paul A. Johnston; Christopher J. Collom; Kimberley J. Johnston Abstract Middle Cambrian basinal strata along the Kicking Horse Rim, including the Burgess Shale Formation, contain lenses of black, thin-bedded, noncalcareous, geochemically anomalous chloritic rock. The lenses have...

... by R.G. McConnell ( 1887 ) of the Geological Survey of Canada (GSC) and then by an assistant of the surveyor Otto Klotz. Their specimens, and some collected by Henri Ami in 1891, were described by Rominger ( 1887 ), Walcott ( 1888 ), and Whiteaves ( 1892 ). Walcott ascribed a Middle Cambrian age...

... and assigned to the former middle Cambrian Amgan Stage of Siberia (Dumicz et al., 1970 ). They occur in a succession of mostly siliciclastic (sandstone and conglomerate) and volcanic (dolerite and doleritic tuff) strata and are restricted to siliceous shales. Unfortunately, the assemblages appear to belong...

...M. JAKE PUSHIE; BRIAN R. PRATT; TRACY C. MACDONALD; GRAHAM N. GEORGE; INGRID J. PICKERING Abstract Beginning with the discovery of the middle Cambrian Burgess Shale, the rare examples of exceptional preservation of soft tissues in fine-grained strata have been celebrated as windows...

... for trilobite biozone correlation in South China, the Tsinghsutung Formation is middle–late Duyunian, Qiandongian (Cambrian Series 2, Stage 4) in age, and equivalent to the Longwangmiaoan in Eastern Yunnan. Numerous sclerites of Wiwaxia occur in association with abundant trilobites...

... the traditional lower-middle Cambrian boundary of Laurentia (see Sundberg et al., 2016 ; Lin et al., 2019 ). The FAD of Eokochaspis nodosa Sundberg and McCollum, 2000 marks the lower boundary of the regional Delamaran Stage, Lincolnian Series (Palmer, 1998b ; Sundberg and McCollum, 2003 ). Above...

... limestone allochthonous blocks (olistoliths) occurring within Middle and Upper Ordovician shales (Bordonaro et al., 1993 ; Keller, 1999 ). Another important source of information on the Cambrian of the southern Precordillera was assembled by Ángel V. Borrello and his associates (Universidad Nacional...

...Neal M. Handkamer; Andrei Ichaso; Brian R. Pratt; M. Gabriela Mángano; Luis A. Buatois Trilobites were recovered from four cores of the middle Cambrian Earlie Formation in southwestern Saskatchewan. Fossils occur in silty mudstone with interbedded siltstone and limestone, deposited in the inner...

... Shale-type animals . Lethaia , 31 : 73 – 88 . Ramsköld , L. 1984 . Silurian odontopleurid trilobites from Gotland . Palaeontology , 27 ( 2 ): 239 – 264 . Rudkin , D. M. 1979 . Healed injuries in Ogygopsis klotzi (Trilobita) from the Middle Cambrian of British Columbia...

... Science , 222 pp. (in Chinese). Conway Morris S. 1985 . The Middle Cambrian metazoan Wiwaxia corrugata (Matthew) from the Burgess Shale and Ogygopsis Shale, British Columbia, Canada . Philosophical...

... ) studied abundant phosphatized material of eodiscoid trilobites from the lower and middle Cambrian of China. These authors showed an early meraspid (meraspid degree 0) cephalon of Shizhudiscus longquanensis with fine ridge-bearing doublure underneath the lateral border (see Zhang & Clarkson, 2012...

... of the lower Middle Cambrian Burgess Shale Formation near Field, British Columbia ( Fig. 1 ). Thus far we have identified only two Sphenothallus specimens from this locality, even though it is the locality from which Byronia was first described ( Matthew, 1899 ) and has yielded numerous specimens of many...

... 770 Conway Morris S. A new metazoan from the Cambrian Burgess Shale of British Columbia Palaeontology 1977 20 623 640 Conway Morris S. The Middle Cambrian metazoan Wiwaxia corrugata (Matthew) from the Burgess Shale and Ogygopsis Shale, British Columbia, Canada...

... . The middle Cambrian metazoan Wiwaxia corrugata (Matthew) from the Burgess Shale and Ogygopsis shale, British Columbia, Canada . Philosophical Transactions of the Royal Society of London , 307 : 507 – 586 . Conway Morris S...

.... , Babcock , L.E. , and Gunther , V.G. , 2015 , Exceptional Cambrian fossils from Utah: A window into the age of trilobites : Utah Geological Survey , Miscellaneous Publication 15-1, 99 p. Rudkin , D.M. , 1979 , Healed injuries in Ogygopsis klotzi (Trilobita) from the middle Cambrian...