Author : Akbar Sohrabi
Publisher :
ISBN 13 :
Total Pages : 558 pages
Book Rating : 4.:/5 (16 download)
Book Synopsis The Trentonian (Late Ordovician) Brachiopod Fauna of Ontario: Evolution Through a Global Warming Event by : Akbar Sohrabi
Download or read book The Trentonian (Late Ordovician) Brachiopod Fauna of Ontario: Evolution Through a Global Warming Event written by Akbar Sohrabi and published by . This book was released on 2013 with total page 558 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis, which examines the evolution of the Late Ordovician (early Katian) brachiopod fauna of Ontario, consists of two main parts: 1) a case study of the Late Ordovician Rhynchotrema-Hiscobeccus lineage of North America to investigate the morphological variations and evolutionary trends of brachiopod fauna in time and space, 2) the paleobiogeography of early Katian brachiopod fauna to explore their distribution patterns at a global scale and controlling factors. During the Katian, the North American craton experienced a first-order marine transgression. The early stage of this event in the early Katian (Trentonian, Chatfieldian) was marked by the development of extensive new habitats for the origin and radiation of brachiopods and other shelly benthos in epicontinental seas. Multivariate analysis, based on nine biometric characters of 171 Late Ordovician rhynchonellide specimens from nine localities in North America, demonstrated quantitatively that Hiscobeccus mackenziensis, as the earliest form of Hiscobeccus, evolved transitional characteristics between Rhynchotrema and the typical Hiscobeccus. During the late Katian (Maysvillian and Richmondian), Hiscobeccus diversified into larger, more globular, and more strongly lamellose shells, especially in the paleoequatorially located inland marine basins. The diversification and morphological trends in the Hiscobeccus lineage are interpreted as the result of adaptation to an environment with relatively shallow, muddy substrates, and low oxygen with unsteady nutrient supply in generally overheated epicontinental seas. Cluster and principal component analyses based on 33 brachiopod faunas of early Katian age, including 252 rhynchonelliform genera, revealed four global distinct faunal provinces, including Kazakhstan, Avalonia, epicontinental Laurentia, and Scoto- Appalachia. The late Darriwilian-early Katian brachiopod faunas of Laurentia show close similarities to those faunas of Siberia, Baltica, and other adjacent tectonic plates and terranes which indicate their semi-cosmopolitan distribution.