Yantanglestes  Yantanglestes is a genus of small, Chinese mesonychid with slender jaws that first appeared during the Early Paleocene in the Thanetian stage. It was found throughout Asia. It is the oldest known mesonychid. "Yantanglestes" became extinct during the Nongshanian division of the Late Paleocene, and lived sympatrically with its descendant genera, including "Dissacus", "Sinonyx" and "Jiangxia".