説明
<jats:p xml:lang="en">A summary of the data on the sequence and distribution of Triasic ammonoid faunas in Canada is provided. From these data a sequence of thirty-one ammonoid zones is recognize d. The zones are grouped into stages and, where appropriate, substages. In the Lower Triassic four stages (Griesbachian, Dienerian, Smithian, and Spa.thian) are recognized ; in the Middle Triassic, two (Anisian and Ladinian); in the Upper Triassic, three (Karnian , Norian, and Rhaetian) . The sequence of stages, substages, and zones, provides a. standard for expressing the age of marine Triassic rocks in Canada. Five new species of ammonoids are described (Otoceras concavum, Olenikites pilatic11s, Gymnotoceras chischa, Progo11oceratites poseidon, Trachyceras obesum) .</jats:p>