Abstract: An incomplete gigantic sauropod femur was found in Ruyang, Henan. Judged by the size of its proximal end, the real length of the femur is probably more than 2m; so it definitely belongs to a gigantic sauropod dinosaur. Although the femur is only preserved as a proximal portion and it is difficult to assign it to a certain generic or species level, its discovery plays an important role in the stratigraphy. Due to the discovery of the sauropod femur, the Mangchuan Formation which was previously considered as belonging to the Paleocene is attributed to the late Early Cretaceous or early Late Cretaceous and its underlying strata-Chenzhaigou Formation- should be also assigned to Cretaceous deposits.