Middle Pleistocene Xenocyon lycaonoides Kretzoi, 1938 in northeastern China and the evolution of Xenocyon-Lycaon lineage

Xenocyon lycaonoides is a well-represented large canid known from the middle Early Pleistocene to Middle Pleistocene in Europe, central Asia, and Alaska, yet its fossil record in eastern Asia is extremely poor. Here we report a well-preserved palatal part of the skull of this species from Jinyuan Cave of Luotuo Hill, Puwan, Dalian of Liaoning Province, northeastern China. The new material confirms the presence of this species in eastern Asia during the early Middle Pleistocene, supporting a Holarctic distribution of this lineage during the Mid-Pleistocene climate change. The morphology of the new material suggests that the Middle Pleistocene X. lycaonoides is more derived than the late Early Pleistocene population, and is distinct from the living Lycaon pictus, and imply the different evolutionary direction from Lycaon. Our analyses support a generic distinction of the Xenocyon from Lycaon. X. lycaonoides can not be the direct ancestor of Lycaon, but is a related taxon that lived in Eurasia and North America. The lineage includes Xenocyon, and Lycaon Brookes, 1827, and partially contributes to Cynotherium Studiati, 1857, showing two independent Island specialisation events, making it one of the most successful lineages of canids ever known.