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TitleThe pelagic crinoids Marsupites and Uintacrinus in the Nanaimo Group of British Columbia: placement of the Santonian/Campanian (Cretaceous) boundary in the northwest Pacific region
AuthorHaggart, J W; Graham, R
Source11th British Columbia Paleontological Symposium, abstracts volume; 2016 p. 6-7
Alt SeriesEarth Sciences Sector, Contribution Series 20160070
PublisherBritish Columbia Paleontological Alliance
Meeting11th British Columbia Paleontological Symposium; Nanaimo; CA; May 20-21, 2016
ProvinceBritish Columbia
NTS92B; 92C; 92E; 92F; 92J; 92K
AreaPacific Coast; Vancouver Island; Gulf Islands
Lat/Long WENS-128.5000 -122.5000 51.0000 48.2500
Subjectspaleontology; Santonian; Campanian; fossil distribution; fossil assemblages; fossils; crinoids; Nanaimo Group; Cretaceous
ProgramGSC Pacific Division
Released2016 01 01
AbstractThe position of the Santonian/Campanian boundary in Upper Cretaceous strata of the Pacific coast of North America has been an issue of discussion for several decades. Matsumoto (1959) placed the boundary in the classic California Upper Cretaceous succession at Big Chico Creek at approximately the first occurrence of the ammonite 'Baculites chicoensis' Trask. Jeletzky (1970) subsequently placed it at the first occurrence of the ammonite 'Submortoniceras chicoense' (Trask) in the California succession and at the first occurrence of the ammonite 'Eupachydiscus haradai sensu' Usher in the Nanaimo Group succession of Vancouver Island, British Columbia. Subsequently, Ward (1978) placed the boundary within the Haradai Subzone of the Elongatum Zone in both California and British Columbia, just beneath the first occurrence of the inoceramid bivalve 'Sphenoceramus schmidti' Michael, associated with the ammonite 'Canadoceras yokoyamai' (Jimbo); this placement was followed approximately by Ward and Haggart (1981). Ward et al. (1983) utilized magnetostratigraphy to place the boundary at just above the base of 'Baculites chicoensis' in California, placing the Elongatum and Schmidti zones of California and British Columbia into the Santonian, and this has been followed in the most recent work (Ward et al., 2012). Because of the generally endemic nature of the Late Cretaceous ammonite and inoceramid faunas of the Pacific basin, as well as challenges in establishing precise magnetostratigraphic chronostratigraphy in this region, a precise correlation of the boundary in the Pacific basin with the international stratotypes in Europe has never been solidly established.

We have recently identified specimens of the pelagic crinoids 'Uintacrinus' and 'Marsupites testudinarius' (von Schlotheim) in strata of the Nanaimo Group of Vancouver Island and the Gulf Islands of British Columbia. Although examples of both of these taxa have been recognized previously in Nanaimo Group strata (J.F. Whiteaves identified 'Uintacrinus' in 1904!), their precise localities and stratigraphic setting were not understood until now. In addition, to the best of our knowledge, these taxa have never been recognized anywhere else in the Pacific basin. Elsewhere, however, 'Marsupites testudinarius' is known from many localities around the globe, including northern Europe and the North American Western Interior, and the last occurrence of the taxon has been proposed as a possible boundary marker for the Santonian/Campanian boundary. The recognition of 'Marsupites testudinarius' in the Pacific region is thus the first definitive faunal evidence marking this stage boundary in the Upper Cretaceous of the Pacific basin and allows confident correlation of the Pacific succession with the European international stratotype stages.
Summary(Plain Language Summary, not published)
This contribution is an abstract of a talk that the authors will present at the 11th British Columbia Paleontological Symposium. The authors will present information about new fossil finds in sedimentary rocks approximately 83 million years old (Cretaceous Period) on southeastern Vancouver Island and the Gulf Islands of British Columbia. The fossils they have identified, crinoids that lived in the world's oceans at the time, have never been recognized previously in the Pacific region of the globe, and they provide the first definitive evidence establishing precise time linkages of the Late Cretaceous sedimentary rocks of the Pacific region with those of northern Europe.

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