<i>Kretzoiarctos</i> gen. nov., the Oldest Member of the Giant Panda Clade

<div><p>The phylogenetic position of the giant panda, <i>Ailuropoda melanoleuca</i> (Carnivora: Ursidae: Ailuropodinae), has been one of the most hotly debated topics by mammalian biologists and paleontologists during the last century. Based on molecular data, it is currently recognized as a true ursid, sister-taxon of the remaining extant bears, from which it would have diverged by the Early Miocene. However, from a paleobiogeographic and chronological perspective, the origin of the giant panda lineage has remained elusive due to the scarcity of the available Miocene fossil record. Until recently, the genus <i>Ailurarctos</i> from the Late Miocene of China (ca. 8–7 mya) was recognized as the oldest undoubted member of the Ailuropodinae, suggesting that the panda lineage might have originated from an <i>Ursavus</i> ancestor. The role of the purported ailuropodine <i>Agriarctos</i>, from the Miocene of Europe, in the origins of this clade has been generally dismissed due to the paucity of the available material. Here, we describe a new ailuropodine genus, <i>Kretzoiarctos</i> gen. nov., based on remains from two Middle Miocene (ca. 12–11 Ma) Spanish localities. A cladistic analysis of fossil and extant members of the Ursoidea confirms the inclusion of the new genus into the Ailuropodinae. Moreover, <i>Kretzoiarctos</i> precedes in time the previously-known, Late Miocene members of the giant panda clade from Eurasia (<i>Agriarctos</i> and <i>Ailurarctos</i>). The former can be therefore considered the oldest recorded member of the giant panda lineage, which has significant implications for understanding the origins of this clade from a paleobiogeographic viewpoint.</p>