We describe six specimens consisting of cranial remains and associated partial presacral axial series belonging to ornithuromorph birds from the Changma locality of the Lower Cretacous Xiagou Formation of northwestern Gansu Province,China.Comparison among specimens is limited by the paucity of overlapping elements,their differing exposed views,and,in some specimens,poor preservation.Despite this,three separate taxa are represented,evidenced by differences in their dentary dentitions:one specimen is edentulous,another has sharp,closely spaced,relatively high-crowned and peg-like teeth,and a third preserves blunt,relatively low-crowned teeth placed in a communal groove,a morphology previously reported among adult birds only in Hesperornithiformes.We propose that the high-crowned specimen may be referred to Gansus yumenensis based on shared similarities with the closely related lteravis huchzermeyeri,including a very similar dentition and an edentulous premaxilla with elongate,unfused frontal processes and no palatal processes.The two other specimens are considered new taxa,for which we erect the names Meemannavis ductrix gen.et sp.nov.and Brevidentavis zhangi gen.et sp.nov.These new specimens confirm that the Changma locality is dominated by ornithuromorph birds and contribute to a better understanding of this important avifauna.The observed variation in dental morphology hints at trophic diversity like that observed in ornithuromorphs from the penecontemporaneous Jehol Group of northeastern China.

Jingmai K.O'Connor;Thomas A.Stidham;Jerald D.Harris;Matthew C.Lamanna;Alida M.Bailleul;Han Hu;Min Wang;Hai-Lu You

Negaunee Integrative Research Center,Field Museum of Natural History,Chicago,IL 60605,USA;Key Laboratory of Vertebrate Evolution and Human Origins,Institute of Vertebrate Paleontology and Paleoanthropology,Chinese Academy of Sciences,Beijing 100044,China;CAS Center for Excellence in Life and Paleoenvironment,Beijing 100044,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;Department of Earth and Environmental Sciences,Dixie State University,St.George,UT 84770,USA;Section of Vertebrate Paleontology,Carnegie Museum of Natural History,Pittsburgh,PA 15213,USA;Department of Earth Sciences,University of Oxford,Oxford,OX1 3AN,UK

植物分类学报

[1]Jingmai K.O'Connor;Thomas A.Stidham;Jerald D.Harris;Matthew C.Lamanna;Alida M.Bailleul;Han Hu;Min Wang;Hai-Lu You-.Avian skulls represent a diverse ornithuromorph fauna from the Lower Cretaceous Xiagou Formation,Gansu Province,China)[J].植物分类学报,2022(05):1172-1198

skulls,ornithuromorph,Xiagou,presacral,Cretacous,dentary,dentitions,edentulous,Hesperornithiformes,Gansus,yumenensis,lteravis,huchzermeyeri,dentition,premaxilla,unfused,Meemannavis,ductrix,Brevidentavis,zhangi,avifauna,ornithuromorphs,penecontemporaneous,Jehol

Avian,diverse,from,Lower,Cretaceous,Formation,Province,China,We,describe,six,specimens,consisting,cranial,remains,associated,partial,axial,series,belonging,birds,Changma,locality,northwestern,Comparison,among,limited,by,paucity,overlapping,elements,their,differing,exposed,views,some,poor,preservation,Despite,this,three,separate,taxa,represented,evidenced,differences,one,another,has,sharp,closely,spaced,relatively,high,crowned,peg,like,teeth,third,preserves,blunt,low,placed,communal,groove,morphology,previously,reported,adult,only,propose,that,may,referred,shared,similarities,related,including,very,elongate,frontal,processes,palatal,two,considered,new,which,erect,names,gen,nov,These,confirm,dominated,contribute,better,understanding,important,observed,variation,dental,hints,trophic,diversity,Group,northeastern

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