Lower Triassic Cephalopods


Series Stage N.A. substage Russian (Primorye) substage Canadian Zone
(Western U.S.)
Russian (Primorye) Zone
Lower Triassic Olenekian
Spathian Russian Subrobustus
(Neopopanoceras haugi)
Subcolumbites multiformis
Pilaticus (Prohungarites -Subcolumbites beds) Neocolumbite insignis
Ayaxian (Columbites-Tirolites beds) Tirolites - Amphistephanites
Smithian Tardus
(Anasibirites Beds)
Anasibirites nevolini
Romunderi
(Meekoceras gracilitatis Zone)
Hedenstroemia bosphorensis
Induan



Stratigraphy
The Olenekian is the approved Global Stage name for the Upper Lower Triassic.  Substages and biozones are recognized in the Far East and North America.  The Hedenstroemia bosphorensis Zone of Southern Primorye (Russia) = the Romunderi Zone of  Canada and the Western U.S. (Meekoceras Beds), and the Anasibirites nevolini Zone of Southern Primorye (Russia) = the Tardus Zone of  Canada and the Western U.S. (Anasibirites Beds).  The IUGS and it's subcommissions are working on setting global boundarys and names for these divisions.


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 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 Romunderi and Tardus 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 Prionitid ammonoids from the Anasibirites beds on this site are lumped into two species, Anasibirites kingianus (Waagen) 1895, and Wasatchites perrini (Mathews) 1929.  (See the two papers by E.T. Tozer 1971 and 1994 for more).  Ammonoids from the Meekoceras beds and Inyoites beds on this site are likewise refered to nominal genera or species.
 


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