First records of a plesiosaurian (Reptilia: Sauropterygia) and an ichthyosaur (Reptilia: Ichthyosauria) from Yukon, Canada

An isolated centrum collected ex situ from marine shales of the Lower Cretaceous (Albian) Arctic Red Formation along the Road River represents the first documented occurrence of a plesiosaurian from Yukon. This centrum represents the northernmost occurrence of plesiosaurians in the Western Interior Sea of North America prior to the establishment of the first continuous seaway (Western Interior Seaway) connecting the Boreal and Tethyan seas. Additionally, this centrum is potentially the secondoldest elasmosaurid specimen known from North America. A second centrum, collected along the Beaver River, is likely derived from the Lower Cretaceous (Lower Albian) Garbutt Formation exposed farther upstream. It represents the first report of an ichthyosaur from Yukon. Additionally, six associated ribs collected from the Arctic Re

Comment on Mustoe, G.E.; Beard, G. Calcite-Mineralized Fossil Wood from Vancouver Island, British Columbia, Canada. Geosciences 2021, 11, 38

We are impressed with the detailed work Mustoe and Beard [...

Reassessment of the late Campanian (Late Cretaceous) heteromorph ammonite fauna from Hornby Island, British Columbia, with implications for the taxonomy of the Diplomoceratidae and Nostoceratidae

<p>Three heteromorph ammonite families are represented within upper Campanian (Upper Cretaceous) strata of the Northumberland Formation exposed on Hornby Island, British Columbia: Baculitidae, Diplomoceratidae and Nostoceratidae. A variety of species are distinguished within these families, of which only three taxa – <i>Baculites occidentalis</i> Meek, 1862, <i>Diplomoceras</i> (<i>Diplomoceras</i>) <i>cylindraceum</i> (Defrance, 1816) and <i>Nostoceras</i> (<i>Nostoceras</i>) <i>hornbyense</i> (Whiteaves, 1895) – have been reported previously. Over the last decade, large new collections and the further preparation of existing collections has provided new taxonomic and morphometric data for the Hornby Island ammonite fauna, from which new descriptions of heteromorph taxa are formulated. Eleven taxa are recognized, including the new species <i>Exiteloceras</i> (<i>Exiteloceras</i>) <i>densicostatum</i> sp. nov., <i>Nostoceras</i> (<i>Didymoceras</i>?) <i>adrotans</i> sp. nov. and <i>Solenoceras exornatus</i> sp. nov. Morphometric analyses of over 700 specimens demonstrate the considerable phenotypic plasticity of these ammonites, which exhibit a broad spectrum of variability in their ornamentation and shell dimensions. A large population sample of <i>Nostoceras</i> (<i>Nostoceras</i>) <i>hornbyense</i> provides an excellent case study of a member of the Nostoceratidae; the recovery of nearly complete, well-preserved specimens enables the re-evaluation of diagnostic traits within the genus <i>Nostoceras</i>. The north-east Pacific <i>Nostoceras</i> (<i>Nostoceras</i>) <i>hornbyense</i> Zone and the global <i>Nostoceras</i> (<i>Nostoceras</i>) <i>hyatti</i> Assemblage Zone are here regarded as correlative, reinforcing a late Campanian age for the Northumberland Formation.</p> <p><a href="http://zoobank.org/urn:lsid:zoobank.org:pub:EEF7416A-3AC7-47CC-8667-806F6A7FE567" target="_blank">http://zoobank.org/urn:lsid:zoobank.org:pub:EEF7416A-3AC7-47CC-8667-806F6A7FE567</a></p

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Integration of macrofossil biostratigraphy and magnetostratigraphy for the Pacific Coast Upper Cretaceous (Campanian–Maastrichtian) of North America and implications for correlation with the Western Interior and Tethys

New biostratigraphic data obtained from measured stratigraphic sections of Santonian through Maastrichtian age located along the west coast of North America necessitate changes to the currently accepted chronostratigraphic framework for this region of the North Pacific biotic province. We recognize and/or define 12 molluscan zones over this interval of the Upper Cretaceous and propose revisions to the currently accepted integration of ammonite zones with global Upper Cretaceous magnetochrons. Our findings demonstrate that there was significantly more faunal interchange between the North American Pacific Coast and both the Western Interior and Gulf Coast regions of North America during the Late Cretaceous than has previously been recognized, and because of this, novel and direct biostratigraphic correlations can be made. These new faunal correlations are augmented with the magnetostratigraphic record from Pacific Coast localities to arrive at better interregional correlation for the Upper Cretaceous globally. The new integration of the global polarity time scale with the local, west coast ammonite zonation now allows better correlation between sections both within the North Pacific province (but geographically far from our study areas) as well as to sections outside of the province itself. However, we note here that previous correlations between biostratigraphy and the top and bottom of magnetochron 33r in west coast North American sections appear to have been in error due to unrecognized, modern-day normal-field overprint of originally reversed polarity in Upper Cretaceous sections. We reinterpret the position of this chron based on this new information

Aptian to Santonian Foraminiferal Biostratigraphy and Paleoenvironmental Change in the Sverdrup Basin as Revealed at Glacier Fiord, Axel Heiberg Island, Canadian Arctic Archipelago

Exceptional exposures of a High Arctic Cretaceous sedimentary record were studied at Glacier Fiord, Axel Heiberg Island. The succession reveals a complex Aptian to Santonian paleoenvironmental history of the Sverdrup Basin that documents several global events. Foraminiferal faunas in combination with rare macrofossil occurrences permit the distinction of nine zones that facilitate biostratigraphic correlations to other High Arctic locales, the Beaufort Mackenzie Basin and the Western Interior Sea. The depositional environment as exposed in the Christopher, Hassel, Bastion Ridge and Kanguk formations changed frequently from a shelf to a shoreface setting. Most sequence boundaries appear to be conformable where shoaling reached lower shoreface levels without subaerial exposure. An exception is the top of the Hassel Formation, correlated here with the Albian/Cenomanian disconformity where a paleosol developed on top of an upper shoreface environment. Transgressive/regressive sequences at Glacier Fiord correspond well with globally recognized transgressive/regressive mega cycles. The lower Christopher Formation shows frequent glendonite beds that attest to the Late Aptian/Early Albian cooling event. The required alkaline conditions for glendonites preserved the only calcareous faunule in the succession. Siliceous microplankton are assumed to be taphonomically removed due to deep burial. The Middle to Late Albian oceanic shelf conditions appeared to be most hospitable and foraminifera grew large tests. In the early Cenomanian and lower Bastion Ridge Formation, benthic species disappear. This sudden loss is interpreted as a consequence of nearby volcanic activity related to the Strand Fiord Formation and basin restriction. This is followed by a period of increased preservation of organic carbon and a distinct increase in marine productivity marking the OAE 2 in the Polar Sea straddling the Cenomanian/Turonian boundary. This interval is expressed in a platy shale, devoid of microbioturbation, but characterized with a repopulation event where the low oxygen tolerant genus Trochammina is the dominant component. The Upper Turonian to Santonian interval of the Kanguk Formation reflects shelf conditions that supported mostly rich benthic assemblages, but have at times minute tests as a response to oxygen depletion