The Haifanggou Formation (simplified Chinese: 海房沟组; traditional Chinese: 海房溝組; pinyin: Hǎifánggōu zǔ), also known as the Jiulongshan Formation (simplified Chinese: 九龙山组; traditional Chinese: 九龍山組; pinyin: Jiǔlóngshān zǔ), is a fossil-bearing rock deposit located near Daohugou (simplified Chinese: 道虎沟; traditional Chinese: 道虎溝) village of Ningcheng County, in Inner Mongolia, northeastern China. The formation consists of coarse conglomerates, sandstone, mudstone, and thin coal layers deposited in deltaic and lacustrine environments.