title: Reanalysis of Wupus agilis (Early Cretaceous) of Chongqing, China as a Large Avian Trace: Differentiating between Large Bird and Small Non-Avian Theropod Tracks.
abstract: Trace fossils provide the only records of Early Cretaceous birds from many parts of the world. The identification of traces from large avian track-makers is made difficult given their overall similarity in size and tridactyly in comparison with traces of small non-avian theropods. Reanalysis of Wupus agilis from the Early Cretaceous (Aptian-Albian) Jiaguan Formation, one of a small but growing number of known avian-pterosaur track assemblages, of southeast China determines that these are the traces of a large avian track-maker, analogous to extant herons. Wupus, originally identified as the trace of a small non-avian theropod track-maker, is therefore similar in both footprint and trackway characteristics to the Early Cretaceous (Albian) large avian trace Limiavipes curriei from western Canada, and Wupus is reassigned to the ichnofamily Limiavipedidae. The reanalysis of Wupus reveals that it and Limiavipes are distinct from similar traces of small to medium-sized non-avian theropods (Irenichnites, Columbosauripus, Magnoavipes) based on their relatively large footprint length to pace length ratio and higher mean footprint splay, and that Wupus shares enough characters with Limiavipes to be reassigned to the ichnofamily Limiavipedidae. The ability to discern traces of large avians from those of small non-avian theropods provides more data on the diversity of Early Cretaceous birds. This analysis reveals that, despite the current lack of body fossils, large wading birds were globally distributed in both Laurasia and Gondwana during the Early Cretaceous.
authors.affiliation: School of the Earth Sciences and Resources, China University of Geosciences, Beijing, 100083, China.
authors.forename: Lida
authors.initials: L
authors.lastname: Xing
authors.affiliation: Peace Region Palaeontology Research Centre, Tumbler Ridge, British Columbia, Canada.
authors.forename: Lisa G
authors.initials: LG
authors.lastname: Buckley
authors.affiliation: Peace Region Palaeontology Research Centre, Tumbler Ridge, British Columbia, Canada.
authors.forename: Richard T
authors.initials: RT
authors.lastname: McCrea
authors.affiliation: Dinosaur Tracks Museum, University of Colorado Denver, Denver, Colorado, United States of America.
authors.forename: Martin G
authors.initials: MG
authors.lastname: Lockley
authors.affiliation: School of the Earth Sciences and Resources, China University of Geosciences, Beijing, 100083, China.
authors.forename: Jianping
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Museo del Jurásico de Asturias MUJA (Jurassic Museum of Asturias), Colunga, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Piñuela
authors.affiliation: Saurierwelt Paläontologisches Museum, Neumarkt, Germany.
authors.forename: Hendrik
authors.initials: H
authors.lastname: Klein
authors.affiliation: Qijiang District Bureau of Land Resources, Chongqing, China.
authors.forename: Fengping
authors.initials: F
authors.lastname: Wang
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001717:Birds / Q000033:anatomy & histology* / Q000145:classification*; D002681:China; D025061:Dinosaurs / Q000033:anatomy & histology; D005528:Foot / Q000033:anatomy & histology*; D005580:Fossils / Q000033:anatomy & histology*