Recent field studies on Upper Silurian stratigraphy and paleontology in the Inner Mongolia Autonomous Region (for short Inner Mongalia) near Bater Obo (=Bateaobao) resulted in the discovery of a small continental island with fossil invertebrates preserved as encrusters (stromatoporoids and corals) attached directly to a rocky shore surface and buried by silty clay mud. The Bater island (named herein) is 610 m ×200 m in size and composed of Ordovician igneous rock (diorite). Limestone strata dating from the Ludlow Epoch (about 420 Ma) surround the island and dip away from the igneous core in a radial pattern. The encrusting fossils occur on the sheltered (south and southeast) side of the island, whereas the north side was exposed to stronger wave activity based on a basal conglomerate unit composed of diorite boulders. This is the first record of an ancient island in China and the first report worldwide of stromatoporoids as members of a rocky-shore community. The island clearly shows distinct windward a Recent field studies on Upper Silurian stratigraphy and paleontology in the Inner Mongolia Autonomous Region (for short Inner Mongalia) near Bater Obo (= Bateaobao) resulted in the discovery of a small continental island with fossil invertebrates preserved as encrusters (stromatoporoids and corals) attached directly The Bater island (named herein) is 610 m × 200 m in size and composed of Ordovician igneous rock (diorite). Limestone strata dating from the Ludlow Epoch (about 420 Ma) surround the island and dip away from the igneous core in a radial pattern. The encrusting fossils occur on the sheltered (south and southeast) side of the island, while the north side was exposed to stronger wave activity based on a basal conglomerate unit composed of diorite This is the first record of an ancient island in China and the first report worldwide of stromatoporoids as members of a rocky-shore community. The island clearly shows distinct windward a