Fossils include the confuciusornithiform bird Eoconfuciusornis.[3] As of 2016[citation needed] this is the oldest bird with a toothless beak known, but it belongs to a very ancestral avian lineage not closely related to living birds.
Qin, Zuohuan; Xi, Dangpeng; Sames, Benjamin; Do Carmo, Dermeval Aparecido; Wang, Xuri; Xu, Yankang; Yu, Zhiqiang; Wei, Feng; Leite, Amanda Moreira (2018), "Ostracods of the non-marine Lower Cretaceous Dabeigou Formation at Yushuxia (Luanping basin, North China): Implications for the early Jehol Biota age", Cretaceous Research, 86: 199–218, Bibcode:2018CrRes..86..199Q, doi:10.1016/j.cretres.2018.03.010, ISSN0195-6671
Rong, Y.-F (2018), "Restudy of Regalerpeton weichangensis (Amphibia: Urodela) from the Lower Cretaceous of Hebei, China", Vertebrata PalAsiatica, 56: 121–136
Kopylov, D. S.; Zhang, H. C. (2015), "New ichneumonids (Insecta: Hymenoptera: Ichneumonidae) from the Lower Cretaceous of north China", Cretaceous Research, 52: 591–604, Bibcode:2015CrRes..52..591K, doi:10.1016/j.cretres.2014.03.012
Zhang, X. W.; Ren, D.; Pang, H.; Shih, C.K. (2009), "Late Mesozoic chresmodids with forewing from Inner Mongolia, China (Polyneoptera: Archaeorthoptera)", Acta Geologica Sinica, 84: 38–46, doi:10.1111/j.1755-6724.2010.00168.x
Ren, D (1995), Insecta, D. Ren, L.W. Lu, Z.G. Guo, S.A. Ji (eds.), Faunae and stratigraphy of Jurassic-Cretaceous in Beijing and the adjacent areas, pp. 47–121
Zhang, J. F (1986), Some fossil insects from the Jurassic of northern Hebei, China, The Paleontology and Stratigraphy of Shandong, pp. 74–84
Hong, Y. C (1984), Insecta, Palaeontological Atlas of North China, II, Mesozoic Volume, pp. 128–185
Further reading
Vickers-Rich, Patricia & Rich, Thomas Hewett (1993); Wildlife of Gondwana. Reed. ISBN0-7301-0315-3