Canadian Triassic ammonoid faunas

Abstract

Data are given on the morphology and distribution of all known Canadian Triassic Ammonoidea, except the Arcestaceae. Material is described from about 850 localities in the Arctic Islands, Yukon, British Columbia and Alberta. Localities in the Arctic Islands are in the Sverdrup Basin. Except for one collection from a well in northwest Alberta, all specimens from Western Canada are from exposures in the Cordillera. A biochronology is proposed covering the whole of the Triassic, from the earliest (Early Griesbachian) to latest (Late Norian). Fifty -six divisions (zones, subzones, horizons) are recognized, grouped within stages and substages as follows: Lower Griesbachian (2), Upper Griesbachian (2), Dienerian (4), Smithian (3), Spathian (2), Lower Anisian (3), Middle Anisian (3), Upper Anisian (2), Ladinian (10), Lower Carnian (3), Upper Carnian (4), Lower Norian (7), Middle Norian (7), Upper Norian (4). The ammonoids are classified as 522 species (243 new) in 256 genera (46 new).

Early Induan (Early Triassic) Cephalopods From the Daye Formation at Guiding, Guizhou Province, South China

“…In spite of significant progress in investigation of Late Permian and Early Triassic ammonoids in the past decades (e.g., Zhao et al 1978;Bando 1979;Zakharov 1992;Dagys and Ermakova 1990;Shevyrev 1990Shevyrev , 1995Tozer 1994;Krystyn et al 2007;Brayard et al 2006Brayard et al , 2007Brayard et al , 2009McGowan and Smith 2007;Brayard and Bucher 2008;Brühwiler et al 2008Brühwiler et al , 2010aBrühwiler et al , b, 2012Shigeta et al 2009;Zakharov and Ehiro 2010), our knowledge this very important group of invertebrates during this crucial for their evolution time remains incomplete.…”

New late Smithian (Early Triassic) ammonoids from the Lusitandiadalan Member, Vikinghøgda Formation, Svalbard

“…Arctoprionites resseri, for instance, has been recorded in British Columbia and in the USA (Tozer, 1994;Brayard et al, 2013;Jattiot et al, in press). This find suggests a broader palaeogeographic range for this taxon than previously thought, and confirms the faunal similarities between the Svalbard Early Triassic and the Canadian regions, as also highlighted by the presence of Arctoprionites nodosus, which is only known from Arctic Canada outside Svalbard, its type locality (Frebold, 1930;Tozer, 1994).…”

Globacrochordicerasgen. nov. (Acrochordiceratidae, late Early Triassic) and its significance for stress-induced evolutionary jumps in ammonoid lineages (cephalopods)

“…Eodanubites; see Guex et al 2010) and forms converging with Globacrochordiceras persisted in the early Anisian (e.g. Columbisculites, Isculites; see Bucher 1989;Tozer 1994b). Hence, the jump in morphology does not relate to the lack of certain facies around the Spathian/Anisian boundary since other taxa with similar shell shapes are present, if one accepts the underlying assumption that some link between facies and shell morphology can be established.…”

“…The standard biochronological scheme of Spathian and Anisian in North America was produced by Silberling & Tozer (1968), Silberling & Wallace (1969), Bucher (1989), Tozer (1994b), and Monnet & Bucher (2005a). Monnet & Bucher (2005b) analysed the biochronology and biodiversity of Anisian ammonoid faunas from Nevada and British Columbia.…”

“…Definition of size classes follows the classification of Korn (2010). The supra-familial classification of Acrochordiceratidae follows Tozer (1981Tozer ( , 1994b Diagnosis. Ammonoids characterized by plicate ribbing (rounded ribs enlarging when crossing the venter without interruption), usually high oval to inflated whorl section, and a relatively indented ceratitic to subammonitic suture line without well-individualized auxiliary lobes.…”