title: A new osteichthyan from the late Silurian of Yunnan, China.
abstract: Our understanding of early gnathostome evolution has been hampered by a generally scant fossil record beyond the Devonian. Recent discoveries from the late Silurian Xiaoxiang Fauna of Yunnan, China, have yielded significant new information, including the earliest articulated osteichthyan fossils from the Ludlow-aged Kuanti Formation. Here we describe the partial postcranium of a new primitive bony fish from the Kuanti Formation that represents the second known taxon of pre-Devonian osteichthyan revealing articulated remains. The new form, Sparalepis tingi gen. et sp. nov., displays similarities with Guiyu and Psarolepis, including a spine-bearing pectoral girdle and a placoderm-like dermal pelvic girdle, a structure only recently identified in early osteichthyans. The squamation with particularly thick rhombic scales shares an overall morphological similarity to that of Psarolepis. However, the anterior flank scales of Sparalepis possess an unusual interlocking system of ventral bulges embraced by dorsal concavities on the outer surfaces. A phylogenetic analysis resolves Sparalepis within a previously recovered cluster of stem-sarcopterygians including Guiyu, Psarolepis and Achoania. The high diversity of osteichthyans from the Ludlow of Yunnan strongly contrasts with other Silurian vertebrate assemblages, suggesting that the South China block may have been an early center of diversification for early gnathostomes, well before the advent of the Devonian "Age of Fishes".
authors.affiliation: Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China.|School of Biological Sciences, Flinders University, South Australia, Australia.
authors.forename: Brian
authors.identifier: http://orcid.org/0000-0002-9983-0762
authors.initials: B
authors.lastname: Choo
authors.affiliation: Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China.|College of Earth Science, University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Min
authors.initials: M
authors.lastname: Zhu
authors.affiliation: Subdepartment of Evolutionary Organismal Biology, Department of Physiology and Developmental Biology, Uppsala University, Uppsala, Sweden.|Center for Advanced Research in Environmental Genomics, University of Ottawa, Ottawa, Canada.
authors.forename: Qingming
authors.initials: Q
authors.lastname: Qu
authors.affiliation: Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China.|Department of Biological Sciences, Kean University, Union, New Jersey, United States of America.
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Yu
authors.affiliation: Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Liantao
authors.initials: L
authors.lastname: Jia
authors.affiliation: Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China.|College of Earth Science, University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Wenjin
authors.initials: W
authors.lastname: Zhao
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000033:anatomy & histology; D002681:China; D005399:Fishes / Q000145:classification*; D005580:Fossils; D010802:Phylogeny