Brachiopod biostratigraphy of the Middle Jurassic on the southern margin of the western Tethys (Morocco, western Algeria) Comparison with the French northern Tethyan margin

A new and yet unpublished palaeontological revision of very important collections accomplished these last thirty years in many localities of Morocco and Western Algeria joined to the already published data, allow us to propose a biostratigraphical succession of the Middle Jurassic Brachiopods suitable to the Southern Margin of the Western Tethys. This Brachiopod scale is correlated with the standard chronostratigraphy based on ammonites. It involves eight zones and six sub-zones separated by five interval zones where Brachiopods are missing. Moreover, brachiopods have not been discovered in Early Aalenian and Late Callovian. Afterwards, the two brachiopod zonations established on the northern and southern margins of the Western Tethys are compared. On a paleontological plane, a new definition of the species Burmirhynchia athiensis warrants to precise its vertical distribution (Parkinsoni and Zigzag zones) and to give a better distinction with Burmirhynchia termierae (Humphriesianum and Niortense zones). (c) 2006 Elsevier Masson SAS. Tons droits reserves.