NEW BRYOZOANS FROM THE EARLY ORDOVICIAN HONGHUAYUAN FORMATION IN TONGZI COUNTY,NORTHERN GUIZHOU
Lower Ordovician bryozoan fossils from patch reefs of the Honghuayuan Formation(Floan Stage)at the Honghuayuan section in Tongzi County,northern Guizhou are elucidated herein.Four species in two genera,i.e.,Orbiramus ovalis,O.minus,O.normalis and Nekhorosheviella semispherica,belong to the Trepostomida and the Esthonioporida are recognized,which greatly expanded the geographical and stratigraphical distribution of these early iconic bryozoans.Moreover,these modular bryozoans demonstrate typical encrusted reef-building construction,implying their contribution in the development of Early Ordovician patch reefs as bryozoan-framestone and bryozoan-microbial blindstone from the Honghuayuan Formation.The fossil evidence from the Honghuayuan Formation shed new light on the evolutionary diversity,modular growth pattern and reef-building mechanism of the early bryozoans.
Bryozoadiversityreef-building mechanismsHonghuayuan FormationLower OrdovicianTongzi County of northern Guizhou