crassatella ponderosa ,outer side, inner side ,fossils from the tertiary period - 第三紀 幅插畫檔、美工圖案、卡通及圖標
the tertiary formation is famously known for its fossils, which document the explosive diversification of life following the extinction of the dinosaurs. - 第三紀 幅插畫檔、美工圖案、卡通及圖標