The Meng-Yin or Mengyin Formation (simplified Chinese: 蒙阴组; traditional Chinese: 蒙陰組; pinyin: Méngyīn Zǔ) is a geological formation in Shandong, China, whose strata date back to the Berriasian and Valanginian stages of the Early Cretaceous. Both the genus and species of were named after the formation.