Paleoecologic and Biogeographic Significance of the Biostromal Organism Palaeoaplysina in the Lower Permian McCloud Limestone, Eastern Klamath Mountains, California

Abstract

Palaeoaplysina is a platy calcareous fossil of possible algal affinity that forms biostromes in the island arc-related Lower Permian McCloud Limestone of the Eastern Klamath Mountains, California. Biostromes of Palaeoaplysina include wackestone, packstone, and boundstone, appear up to 4 m thick and over 100 m long, and contain common phylloid and encrusting calcareous algae. Biostromes also contain at least 23 species of foraminifers, coarals, bryozoans, brachiopods, annelids, molluscs, and crinoids. Aside from encrusting bryozoans and annelids, this associated fauna consists of immigrants from level-bottom communities with no special co-adaptations to biostrome formers. Other occurrences of Palaeoaplysina form a discrete belt around the northern rim of the late Paleozoic Laurentian continent from the Urals to Idaho. Presence of Palaeoaplysina in the McCloud Limestone is a significant biogeographic link with North America and argues that the Eastern Klamath Mountains are not a far-travelled terrane.