title: A late Paleocene probable metatherian (?deltatheroidan) survivor of the Cretaceous mass extinction.
abstract: Deltatheroidans are primitive metatherian mammals (relatives of marsupials), previously thought to have become extinct during the Cretaceous mass extinction. Here, we report a tiny new deltatheroidan mammal (Gurbanodelta kara gen. et sp. nov.) discovered at the South Gobi locality in China (Xinjiang Province) that is the first Cenozoic record of this clade and renders Deltatheroida a Lazarus taxon (with a new record 10 million years younger than their supposed extinction). The vertebrate fauna associated with Gurbanodelta is most similar to that from the slightly older late Paleocene Subeng locality in Inner Mongolia. The upper molars of Gurbanodelta exhibit a broad stylar shelf with one prominent cusp (stylocone), and a paracone that is sharp and significantly taller than the metacone. The lower molar tentatively assigned to Gurbanodelta has a very small talonid without an entoconid. This combination of these features is known only in deltatheroidans. Phylogenetic analysis places Gurbanodelta as the sister taxon of the North American latest Cretaceous Nanocuris. Gurbanodelta is the smallest-known deltatheroidan, and roughly the same size as the smallest living marsupial. It is likely that the Gurbanodelta lineage dispersed between Asia and North America as part of known intercontinental mammalian dispersals in the late Paleocene, or possibly earlier.
authors.affiliation: Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, 142 Xi Zhi Men Wai Street, Beijing, 100044, China.|CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing, 100101, China.|University of Chinese Academy of Sciences, Beijing, 100049, China.
authors.forename: Xijun
authors.initials: X
authors.lastname: Ni
authors.affiliation: Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, 142 Xi Zhi Men Wai Street, Beijing, 100044, China.|CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing, 100101, China.|University of Chinese Academy of Sciences, Beijing, 100049, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Li
authors.affiliation: Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, 142 Xi Zhi Men Wai Street, Beijing, 100044, China.|University of Chinese Academy of Sciences, Beijing, 100049, China.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Stidham
authors.affiliation: Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, 142 Xi Zhi Men Wai Street, Beijing, 100044, China.|University of Chinese Academy of Sciences, Beijing, 100049, China.
authors.forename: Lüzhou
authors.initials: L
authors.lastname: Li
authors.affiliation: Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, 142 Xi Zhi Men Wai Street, Beijing, 100044, China.|University of Chinese Academy of Sciences, Beijing, 100049, China.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Lu
authors.affiliation: Division of Paleontology, American Museum of Natural History, Central Park West at the 79th Street, New York, NY 10024, USA.
authors.forename: Jin
authors.initials: J
authors.lastname: Meng
mesh_terms: D000818:Animals; D002681:China; D003817:Dentition; D053476:Extinction, Biological; D005580:Fossils; D005843:Geography; D008322:Mammals / Q000033:anatomy & histology / Q000502:physiology*; D010802:Phylogeny; D013997:Time Factors