ABSTRACT

The group of Middle and Upper Triassic spiriferinids from Northeastern British Columbia, previously referred to by various authors as Spiriferina borealis Whiteaves, Spiriferina coreyi Smith and Spiriferina onestae McLearn, and characterised by a unicostate median sinus, have been r-investigated. Serial-sections indicate a true affinity with Spiriferina D'Orbigny s.s. Considerable variation exists in the number of lateral costae, type of costation, shape of anterior commissure and length of the hinge-line and there is complete gradation from brachythyrid to megistothyrid forms. Spiriferina coreyi Smith, originally described from the Upper Karnian of California, is based on a single, poorly-preserved ventral valve and is regarded as a "nomen dubium." Spiriferina borealis Whiteaves and Spiriferina onestae McLearn are placed in the synonomy of Spiriferina abichi Oppel (=S. griesbachi Bittner) from the Norian of the Himalayas and the Oman; this species has previously been recognised only in the Indo-Pacific or Tethyan Province. The North American representative of the S. abichi group is re-described and compared with similar forms in the Indo-Pacific Province. The British Columbia S. abichi ranges from the Ladinian, in which the variety S. abichi var. onestae predominates and is an integral part of the Nathorstites fauna, through the Lower and Middle Karnian "Lima" poyana fauna to the Upper Karnian, where it finally occurs 450 below the Styrites ireneanus zone, in the Gonionotites-Malayites Major Zone, on Pardonet Hill.