Lower Triassic Cephalopods

Series Stage Substage Utah Biostratigraphy
Lower Triassic Olenekian
Spathian Neopopanoceras haugi
Prohungarites -Subcolumbites beds
Columbites-Tirolites beds
Smithian Xenoceltites Beds
Anasibirites Beds
Owenites Beds                               Inyoites Horizon
                                                          Hanielites Horizon
Minersvillites Beds
Flemingites Beds
Inyoites beaverensis Beds
Lower beds
Preflorianites-Kashmirites Beds
Meekoceras millardense Beds
Meekoceras olivieri Beds
Radioceras evolvens Beds
Vercherites undulatus Beds

References: Mathews,Asa A. L., 1929, The Lower Triassic Cephalopod Fauna of the Fort Douglas Area, Utah, Walker Museum Memoirs Vol.1 No.1 University ofChicago Press; Hose, R. K., and Repenning, C. A., 1959, Stratigraphy of Pennsylvanian, Permian, and Lower Triassic Rocks of the ConfusionRange, West-Central Utah, A.A.P.G. Bulletin vol. 43, no. 9; Tozer, E. T., 1971, TriassicTime and Ammonoids: Problems and Proposals, Canadian Journal of EarthScience, 8; Tozer, E. T., 1994, Canadian Triassic Ammonoid Faunas, GSC Bulletin 467; D. A.Stephen, K. G. Bylund, P. J. Bybee andW. J. Ream, 2010, Ammonoid Beds in the Lower Triassic Thaynes Formation of western Utah, USA, in: Cephalopods – Present and Past, edited by K. Tanabe,Y. Shigeta  and T. Sasaki & H. Hirano. Tokai University Press, Tokyo, p. 243-252; Brayard, A., Bruhwiler, T., Bucher, H. and Jenks, J., 2009, Guodunites, A Low-Palaeolatitude and Trans-Panthalassic Smithian (Early Triassic) Ammonoid Genus  Palaeontology, Vol. 52, Part 2, pp. 471-481; Brayard, A., Bylund, K. G., Jenks, J., Stephen, D. A., Olivier, N., Escarguel, G., Fara, E. & Vennin, E., 2013. Smithian ammonoid faunas from Utah: implications for Early Triassic biostratigraphy, correlations and basinal paleogeography. Swiss Journal of Paleontology 132:141-219; Poborski, S. J., 1954, Virgin Formation (Triassic) of the St. George, Utah, Area, Geological Society of America Bulletin vol. 65; Kummel, B., 1969, Ammonoids of the Late Scythian (Lower Triassic), Bulletin Museum of Comparative Zoology Vol.137 no. 3;  Guex, J., Hungerbuhler, A., Jenks, J., Taylor, D., Bucher, H., 2005, Dix-huet nouveaux genres d'ammonites du Spathien (Trias inferieur) de l'Ouest americain (Idaho, Nevada, Utah et Californie) Note preliminaire. Bull. Geol. Lausanne 362, Numero Special, Mai 2005, Guex, Jean, Alexandre Hungerbühler, James F. Jenks, Luis O’Dogherty, Viorel Atudorei, David G. Taylor, Hugo Bucher, Annachiara Bartolini, 2010, SPATHIAN (LOWER TRIASSIC) AMMONOIDS FROM WESTERN USA (IDAHO, CALIFORNIA, UTAH AND NEVADA), Mémoire de Géologie (Lausanne), n°49

Taxonomy (Lumper or Splitter?)

As for Smithian Taxonomy on this web page, all ammonoids are nominal.
Because of the variable morphology in some populations all specimens are a seperate species, or all are one specie with variable morphology.  Mathews (1929) described (a) 32 species of Anasibirites, 5 species of Gurlyeites, 9 of Hemiprionites "Goniodiscus" and 1 of  Kashmirites, and (b) 4 species of  Wasatchites, 3 of Kashmirites and 1 of Keyserlingites, from Cephalopod Gulch near Salt Lake City, Utah.  Later workers placed alot of them (a) in synonomy with Anasibirites kingianus (Waagen) and (b) in Wasatchites.  In the Anasibirites Beds (about 300mm thick) of the Confusion Range of western Utah. there are representatives of all these genera, they grade from Hemiprionites to Anasibirites to Gurleyites to Arctoprionites to Wasatchites with intermediates between each.  To use a typological taxonomy would mean many new species, to use a population taxonomy would mean one or two species.  Given the short duration of the Smithian and the difference between the faunas of the Meekoceras and Anasibirites zones it seems best to refer all to nominal species (with generic modifiers in quotes on some just to tell what the specimen looks like).  So for the time being most Prionitid ammonoids from the Anasibirites beds on this site are lumped into two species, Anasibirites multiformis Welter 1922, and Wasatchites perrini Mathews 1929.  (See the two papers by E.T. Tozer 1971 and 1994 for more).

  | Home | Chart |