Archaeopteryx sp. (private, undescribed #12) is a small Solnhofen (Late Jurassic) bird basal to the Scansoriopterygidae. Note the relatively small, wide skull and large premaxillary teeth.

Mei long (IVPP V12733, Xu and Norell 2004, Early Cretaceous) is famous for its 3D preservation in a curled up sleeping posture. Originally considered a young juvenile, bird-like troodontid, Mei long nests in the large reptile tree between the xx specimen of Archaeopteryx and Scansoriopteryx amid the scansoriopterygid basal birds. A second specimen, DNHM D2154 (Gao et al. 2012), was also preserved in a sleeping posture. Mei is derived from a sister to the Munich specimen of Archaeopteryx and was basal to other scansoriopterygids.

Chongmingia zhengi (Wang et al. 2016; Aptian, Early Cretaceous) is a basal scansoripterygid bird lacking most of the skeleton.

Jixiangornis orientalis (Ji et al 2002; Aptian, Early Cretaceous) nests between Mei any Yi among in the scansoripterygid bird clade, slightly larger than the others.

Yi qi (Xu et al. 2015; Late Jurassic) the authors noted a new long bony element in the fore limb of Yi qi never before seen on any bird, dinosaur, or archosaur. They labeled the new bone a ‘styliform element’ in accord with similar elements in flying squirrels. That long bone on one side is displaced radius. On the other side a displaced ulna. This is the last of the long-neck scansoriopterygids.

Ambopteryx longibrachium (Wang et al. 2019; Late Jurassic; IVPP V24192; 32 cm long) was originally considered another bird with bat wings supported by a 'styliform' bone. Examination revealed no such bone. A displaced ulna was misidentified. Ambopteryx is midway in size between Yi and Scansoriopteryx. A dense layer of feathers is also preserved.

Scansoriopteryx heilmanni (Czerkas and Yuan 2002, CAGS02-IG-gausa-1/DM 607; Late Jurassic) is a small basal bird (as recovered by the large reptile tree). It has a bird-like pelvis, but this has not been recognized by other paleontologists who identified the displaced ischium as the pubis and the pubis as the ischium. That made it appear that the pubis did not point posteriorly, as it does in all birds and related taxa. This is the first of the short-neck scansoriopterygids.

Epidexipteryx hui (Zhang et al. 2008, IVPP V 15471; Late Jurassic) another scansoriopterygid also has a mistakenly identified pubis and ischium. This anurognathid-like basal bird has the largest teeth relative to its skull of any bird. Zhang et al. thought Epidexipteryx was a bizarre maniraptoran nesting just basal to birds

Omnivoropteryx sinousaorum (Czeraks and Ji 2002; Early Cretaceous) nests with Epidexipteryx (above).

Czerkas SA and Yuan C 2002. An arboreal maniraptoran from northeast China. Pp. 63-95 in Czerkas, S.J. (Ed.), Feathered Dinosaurs and the Origin of Flight. The Dinosaur Museum Journal 1. The Dinosaur Museum, Blanding, U.S.A.

Czerkas SA and Ji Q 2002. A preliminary report on an omnivorous volant bird from northeast China.” In: Czerkas, SJ (editor): Feathered Dinosaurs and the origin of flight. The Dinosaur Museum Journal 1:127-135.

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 et al (6 co-authors) 2002. A New Avialian Bird - Jixiangornis orientalis gen. et sp. nov. - from the Lower Cretaceous of Western Liaoning, NE China. Journal of Nanjing University (Natural Sciences). 38 (6): 723–736.

Wang M, Wang X, Wang Y and  Zhou Z 2016. A new basal bird from China with implications for morphological diversity in early birds. Nature Scientific Reports 6, art. 19700, 2016.

Wang M, O'Connor JK, Xu X and Zhou Z 2019. A new Jurassic scansoriopterygid and the loss of membraneous wings in theropod dinosaurs. Nature 569:256–259.

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

Xu X and Norell MA 2004. A new troodontid dinosaur from China with avian-like sleeping posture. Nature 431:838-841.

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.

wiki/Chongmingia
wiki/Scansoriopteryx
wiki/Yi
wiki/Epidexipteryx
wiki/Omnivoropteryx
wiki/Ambopteryx
wiki/Jixiangornis