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Sato T.,Tokyo Gakugei University | Sato T.,Canadian Museum of Nature | Zhao L.-J.,Zhejiang Museum of Natural History | Wu X.-C.,Canadian Museum of Nature | Li C.,CAS Institute of Vertebrate Paleontology and Paleoanthropology
Palaeontology | Year: 2014

An adult skeleton of the pistosauroid sauropterygian Yunguisaurus liae reveals a number of morphological features not observed in the holotype, such as the complete morphology of the skull roof, stapes, atlas and axis, ventral view of the postcranium, and nearly complete limbs and tail. Size and morphological differences between the two specimens are mostly regarded as ontogenetic variation, and newly added data did not affect the phylogenetic relationships with other pistosauroids significantly. The number of mesopodia (11 carpals and 8 tarsals) exceeds that known in any other Triassic marine reptiles and does not serve as a precursor of the plesiosaurian pattern with fewer mesopodia of different topology; it demonstrates variability of the limb morphology among the Triassic pistosauroids. The pectoral girdles of Corosaurus, Augustasaurus and Yunguisaurus may indicate early stages of the adaptation towards the plesiosaurian style of paraxial limb movements with ventroposterior power stroke. © The Palaeontological Association. Source

Wang Y.,Zhejiang University | Chen S.,Zhejiang Museum of Natural History | Ding P.,Zhejiang University
Journal of Biogeography | Year: 2011

Aim A fundamental question in community ecology is whether general assembly rules determine the structure of natural communities. Although many types of assembly rules have been described, including Diamond's assembly rules, constant body-size ratios, favoured states, and nestedness, few studies have tested multiple assembly rule models simultaneously. Therefore, little is known about the relative importance of potential underlying factors such as interspecific competition, inter-guild competition, selective extinction and habitat nestedness in structuring community composition. Here, we test the above four assembly rule models and examine the causal basis for the observed patterns using bird data collected on islands of an inundated lake. Location Thousand Island Lake, China. Methods We collected data on presence-absence matrices, body size and functional groups for bird assemblages on 42 islands from 2007 to 2009. To test the above four assembly rule models, we used null model analyses to compare observed species co-occurrence patterns, body-size distributions and functional group distributions with randomly generated assemblages. To ensure that the results were not biased by the inclusion of species with extremely different ecologies, we conducted separate analyses for the entire assemblage and for various subset matrices classified according to foraging guilds. Results The bird assemblages did not support predictions by several competitively structured assembly rule models, including Diamond's assembly rules, constant body-size ratios, and favoured states. In contrast, bird assemblages were highly significantly nested and were apparently shaped by extinction processes mediated through area effects and habitat nestedness. The nestedness of bird assemblages was not a result of passive sampling or selective colonization. These results were very consistent, regardless of whether the entire assemblage or the subset matrices were analysed. Main conclusions Our results suggest that bird assemblages were shaped by extinction processes mediated through area effects and habitat nestedness, rather than by interspecific or inter-guild competition. From a conservation point of view, our results indicate that we should protect both the largest islands with the most species-rich communities and habitat-rich islands in order to maximize the number of species preserved. © 2011 Blackwell Publishing Ltd. Source

Xu G.-H.,CAS Institute of Vertebrate Paleontology and Paleoanthropology | Zhao L.-J.,Zhejiang Museum of Natural History | Shen C.-C.,CAS Institute of Vertebrate Paleontology and Paleoanthropology
Biology Letters | Year: 2015

Gliding adaptations in thoracopterid flying fishes represent a remarkable case of convergent evolution of overwater gliding strategy with modern exocoetid flying fishes, but the evolutionary origin of this strategy was poorly known in the thoracopterids because of lack of transitional forms. Until recently, all thoracopterids, from the Late Triassic of Austria and Italy and theMiddle Triassic of South China, were highly specialized 'four-winged' gliders in having wing-like paired fins and an asymmetrical caudal fin with the lower caudal lobe notably larger than the upper lobe. Here, we show that the new genus Wushaichthys and the previously alleged 'peltopleurid' Peripeltopleurus, from the Middle Triassic (Ladinian, 235-242 Ma) of South China and near the Ladinian/Anisian boundary of southern Switzerland and northern Italy, respectively, represent the most primitive and oldest known thoracopterids. Wushaichthys, the most basal thoracopterid, shows certain derived features of this group in the skull. Peripeltopleurus shows a condition intermediate between Wushaichthys and Thoracopterus in having a slightly asymmetrical caudal fin but still lacking wing-like paired fins. Phylogenetic studies suggest that the evolution of overwater gliding of thoracopteridswas gradual in nature; a four-stage adaption following the 'cranial specialization-asymmetrical caudal fin-enlarged paired fins-scale reduction' sequence has been recognized in thoracopterid evolution. Moreover, Wushaichthys and Peripeltopleurus bear hooklets on the anal fin of supposed males, resembling those of modern viviparious teleosts. Early thoracopterids probably had evolved a live-bearing reproductive strategy. © 2015 The Author(s) Published by the Royal Society. All rights reserved. Source

Xu G.-H.,CAS Institute of Vertebrate Paleontology and Paleoanthropology | Zhao L.-J.,Zhejiang Museum of Natural History | Coates M.I.,University of Chicago
Biology Letters | Year: 2014

The Halecomorphi are a major subdivision of the ray-finned fishes. Although living halecomorphs are represented solely by the freshwater bowfin, Amia calva, this clade has a rich fossil history, and the resolution of interrelationships among extinct members is central to the problem of understanding the origin of the Teleostei, the largest clade of extant vertebrates. The Ionoscopiformes are extinct marine halecomorphs that were inferred to have originated in the Late Jurassic of Europe, and subsequently dispersed to the Early Cretaceous of the New World. Here, we report the discovery of a new ionoscopiform, Robustichthys luopingensis gen. et sp. nov., based on eightwell-preserved specimens from the Anisian (242-247 Ma), Middle Triassic marine deposits of Luoping, eastern Yunnan Province, China. The new species documents the oldest known ionoscopiform, extending the stratigraphic range of this group by approximately 90 Ma, and the geographical distribution of this group into the Middle Triassic of South China, a part of eastern Palaeotethys Ocean. These new data provide a minimum estimate for the split of Ionoscopiformes from its sister clade Amiiformes and shed new light on the origin of ionoscopiform fishes. © 2014 The Author(s). Source

Wang Y.,Zhejiang University | Ding P.,Zhejiang University | Chen S.,Zhejiang Museum of Natural History | Zheng G.,Beijing Normal University
Landscape and Urban Planning | Year: 2013

Nestedness is a pattern frequently observed in fragmented systems and has important implications for conservation. The few existing nestedness studies in urban landscapes have focused on the resident and breeding birds, while little attention has been paid to the wintering birds. Using distribution data of 60 bird species collected on 20 urban woodlots in Hangzhou, China, we tested for the existence of the nestedness and the underlying mechanisms for breeding birds and wintering species separately. We used the line-transect method to survey bird occupancy and abundance on 20 woodlots. We used two recently developed metrics, WNODF and NODF, to estimate nestedness. We used partial Spearman rank correlations to examine the associations of nestedness and habitat variables (area, isolation, habitat richness and human disturbance). We also used information-theoretic methods based on Akaike Information Criterion (AIC) to determine ecological processes underlying nestedness. The community compositions of breeding birds and wintering species were all significantly nested. Habitat nestedness is the main driver of species nestedness for all the bird assemblages. Human disturbance played an important role in the development of species nestedness for breeding birds, but not for wintering species. Nestedness of all the bird assemblages was not due to passive sampling, selective extinction or selective colonization. From a conservation viewpoint, our results indicate that we should protect woodlots with diverse habitats priorly and refrain from using breeding birds and wintering species as surrogates for each other in developing conservation planning. © 2012 Elsevier B.V. Source

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