Cranial osteology and palaeobiology of the Early Cretaceous bird Jeholornis prima (Aves: Jeholornithiformes) Author Hu, Han Author Wang, Yan Author Fabbri, Matteo Author O, Jingmai K. Author Connor Author Mcdonald, Paul G. Author Wroe, Stephen Author Yin, Xuwei Author Zheng, Xiaoting Author Zhou, Zhonghe Author Benson, Roger B. J. text Zoological Journal of the Linnean Society 2023 2023-05-01 198 1 93 112 https://academic.oup.com/zoolinnean/article/198/1/93/6768673 journal article 10.1093/zoolinnean/zlac089 0024-4082 EMENDED DIAGNOSIS OF J. PRIMA Based on the morphological study of this specimen, we provide the following revised diagnosis for J. prima . A large stem bird with the following combination of features: premaxilla edentulous with short maxillary process; two teeth with blunt crowns in maxilla and three relatively smaller teeth in dentary (new); paired, sheet-like preorbital ossifications present near the nasals (new, autapomorphy); C-shaped lacrimal with short rostrodorsal ramus and lacrimal foramen (new); unreduced postorbital forming a complete postorbital bar with jugal (new); pterygoid rami of vomer much longer than the fused rostral portion, expanded in the middle and lacking the caudodorsal process (new); palatine with broad pterygoid wing and jugal process (new); narrow and restricted mandibular fenestra between prearticular and surangular (new); 27 caudal vertebrae in total, with the transition point occurring after the fifth vertebra; lateral trabecula of sternum absent; caudalmost pair of sternal ribs expanded; first phalanx of the third manual digit twice as long as the second phalanx; ratio of forelimb (humerus plus ulna plus carpometacarpus) to hindlimb (femur plus tibiotarsus plus tarsometatarsus) of ~1.2:1; dorsal margin of the ilium nearly straight and craniodorsal–caudoventrally oriented (modified from Zhou & Zhang, 2002 ; O’Connor et al. , 2012 ; Zheng et al. , 2020 ).