The evolution, correlation, and paleogeographic significance of the Permian ammonoid family Cyclolobidae

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Abstract

The Permian ammonoid family Cyclolobidae Zittel is essentially of Middle Permian age, and most species ranged over the paleotropical into temperate regions, and lived for no more than one to three stages. The time ranges of the three principal genera, Waagenoceras, Timorites and Cyclolobus overlap to some degree, so correlation must be based on species rather than genera. Cyclolobus evolved from Godthaabites, and both inhabited temperate paleolatitudes on the whole. Cyclolobus inhabited a small region, now dispersed around the rim of the Indian Ocean. The Waagenoceras - Timorites lineage, contemporaneous with the Godthaabites-Cyclolobus suite, inhabited paleotropical latitudes, and Timorites is found around the rim of the Pacific Ocean. Such genera, restricted in longitudinal as well as latitudinal distribution, are important in constructing pre-drift distribution of plates.

The Kalabarghian and Chhidruan faunas of the Salt Range are identical with the Capitan Stage (sensu lato) of Texas. Younger Permian rocks and faunas are subdivided into the Kathwai fauna, the Baisalian, Vedian, Ogbinan faunas, followed by the Makarewan Stage of New Zenland.

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