Archaeopteryx bavarica (BSP 1999 I 50, Wellnhofer 1999; Late Jurassic) nests between the #12 specimen, above, and the rest of the Scansoriopterygidae. Note the third finger is still short, but more robust. Later taxa elongate this finger.

Jeholornis prima (LPM 0193, Wellnhofer 199, 80cm long; 120 mya Early Cretaceous; originally Shenzhouraptor sinensis) was originally considered a "transitional phase between the Dinosauria and Aves". Here it is a large archaeopteryx-like flightless bird at the base of the Scansoriopterygidae. The third finger is longer than the second here.

Jeholornis ?prima (IVPP V14978, Wu et al 2023, 50cm long; Early Cretaceous; was found with plant material in its gut. Here it is transitional between J prima and J curvipes (below). It lacks teeth and has a shorter skull, similar to that of the extant plant-eating bird, the hoatzin, Opisthocomus.

Jeholornis curvipes (LPM 0193, Lefevre et al. 2014;, 40+cm long; 120 mya; Yixian Fm. Early Cretaceous) has a robust premaxilla with teeth and a gracile maxilla without teeth. The abstract reported, "A revision of long-tailed birds from China and a phylogenetic analysis of basal Avialae suggest that Jeholornithiformes were paraphyletic, with Jixiangornis orientalis being the sister-taxon of pygostylia. The phylogenetic analysis also recovered that the tail reduction is a unique event in the evolution of birds. Jeholornis species were cursorial, nonperching, and seed-eating birds."

Shenzhouraptor sinensis (Ji et al. 2002; Early Cretaceous) Here the former Hong Kong Science Museum specimen nests with and is considered a junior synonym of Jeholornis.

Gao C, Morschhauser EM, Varricchio DJ, Liu J, Zhao B 2012. Farke AA ed. "A Second Soundly Sleeping Dragon: New Anatomical Details of the Chinese Troodontid Mei long with Implications for Phylogeny and Taphonomy". PLoS ONE 7 (9): e45203. doi:10.1371/journal.pone.0045203. PMC 3459897. PMID 23028847.

Ji Q, Ji S, You H, Zhang J, Yuan C, Ji X, Li J and Li Y 2002. Discovery of an avialae bird - Shenzhouraptor sinensis gen. et sp. nov - from Chin]. Geological Bulletin of China, 21(7): 363-369.

Lefèvre U, Hu D, Escuillié F, Dyke G and Godefroit P 2014. A new long-tailed basal bird from the Lower Cretaceous of north-eastern China. Biological Journal of the Linnean Society. 113 (3): 790–804. doi:10.1111/bij.12343

Wu et al (5 co-authors) 2023. Intra-gastric phytoliths provide evidence for folivory in basal avialans of the Early Cretaceous Jehol Biota. Nature communications https://doi.org/10.1038/s41467-023-40311-z

Xu X, Zheng X-T, Sullivan C, Wang X-L, Xing l, Wang Y, Zhang X-M, O’Connor JK, Zhang F-C and Pan Y-H 2015. A bizarre Jurassic maniraptoran theropod with preserved evidence of membranous wings. Nature (advance online publication)
doi:10.1038/nature14423

Zhang F, Zhou Z-H, Xu X, Wang X and Sullivan C 2008. A bizarre Jurassic maniraptoran from China with elongate ribbon-like feathers. Nature 455 doi:10.1038:1105-1108.

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