Protopteryx fengningensi (Zhang and Zhou 2000, Barremian/Aptian, 131 mya) the most primitive enantiornithine, was starling-sized (10cm) had no pygostyle, had two elongate tail feathers that lacked barbs and ram. Preserved with flight and down feathers.

Click here for more on Microcursor.

Imparavis attenboroughi (Wang et al 2024, STM11-176, Early Cretceous) was considered a toothless enantiornithine. Here it nests with Protopteryx, which has teeth and is among the most basal enantiornithines. Protopteryx was not tested by Wang et al. The slender toes have relaively large curved claws.

Nicrocursor sanspedes (Knoll et al. 2018; Kaye et al. 2019; MPCM-LH-26189 Las Hoyas locality (Barreminian, Early Cretaceous); 4cm long, sans tail feathers). This taxon was originally considered a hummingbird-sized enantiornithine, but nests in the LRT between Solnhofen birds and basal enantiornithes. The tail is transitional from long and unfused to a pygostyle, convergent with other clades that also evolve a pygostyle. Lacking primary feathers, this specimen was considereed a nestling, unable to fly. However, the fact that it nests as a phylogenetically miniaturized taxon basal to Enantiornthes and crown birds indicates a possible small adult status. Previously considered a hatchling due to its tiny size, here it is considered the second smallest dinosaur, next to the extant bee hummingbird and flightless due to its small fingers.

Sinornis santensis (Sereno and Rao 1992, Early Cretaceous) sparrow-sized, excellent flyer with large perching hallux despite having unfused hand and wrist bones. Only moderately curved manual unguals.

Avimaia schweitzerae (Bailleul et al. 2019; Early Cretaceous; IVPP V25371; at left) reported on the posterior half of an Early Cretaceous enantiornithine bird from China. It nested most closely to Cathayornis, another bird with an extremely deep ventral pelvis. A straight narrow 'rib' may instead by a radius on this likely flightless genus.

Cathayornris yandica (Zhou, Jin and Zhang. 1992, IVPP V9769; Aptian, Early Cretaceous; at right) toothy jaws, large naris, domed skull, large claws on first two wing fingers, coracoids large and equal to the scapula length, long gracile curved pubis, pygostyle shorter than remaining caudals.

Shenqiornis mengi (Wang et al. 2010; O'Connor and Chiappe 2011; Early Cretaceous; DNHM D2950-2951; scale bar = 1cm) is an enantiornithine with a well-preserved skull.

IVPP V12707 hatchling (Wang et al. 2021; Early Cretaceous) nests with Shenqiornis in the LRT.

Yuanchuavis kompsosoura (Wang et al. 2021; Wang et al 2022; Early Cretaceous; IVPP V27883) is an enantiornithine close to Pengornis, lacking pectoral elements, but preserving a long pin tail. The skull is reconstructed here from µCT elements.

Pengornis houi (Zhou, Clarke, & Zhang 2008; Early Cretaceous; IVPP V15336) is a large enantiornithine nesting with Cathayornis and Sulcavis.

Boahaiornis guoi (Hu et al. 2011; Early Cretaceous; LPM B00167; IVPP V17963) is a large enantiornithine nesting with Cathayornis and Sulcavis.

Parapengornis eurycaudatus (Hu, O'Connor, Zhou and Farke 2015, IVPP V18687; Early Cretaceous) is a sister to Pengornis and closer to Gretcheniao.

Gretcheniao sinensis (Chiappe et al. 2019; BMNHC Ph 829; Early Cretaceous) is a sister to Pengornis.

Chiappeavis magnapremaxillo (O'Connor et al. 2016, Early Cretaceous) is an enantiornithine bird with a pygostyle tail. The short tail was tiped with a fan of feathers. The forelimbs were quite large.

Chiappeavis juvenile (O'Connor et al. 2020, Early Cretaceous STM34-1) is an enantiornithine with a pygostyle tail and immature molting feathers. The short tail was naked. The forelimbs were shorter. The hindlimbs were longer than in the adult.

Bailleul AM, et al. 2019. An Early Cretaceous enantiornithine (Aves) preserving an unlaid egg and probable medullary bone. Nature Communications. 10 (1275). doi:10.1038/s41467-019-09259-x

Chiappe LM, Meng QJ, Serrano F, Sigurdsen T, Min W, Bell A and Liu D 2019. New Bohaiornis-like bird from the Early Cretaceous of China: enantiornithine interrelationships and flight performance. PeerJ 7:e7846 DOI 10.7717/peerj.7846

Hu D, Li L, Hou L and Xu X 2011. A new enantiornithine bird from the Lower Cretaceous of western Liaoning, China. Journal of Vertebrate Paleontology. 31 (1): 154–161.

Hu H, O'Connor J, Zhou Z and Farke AA. 2015. A New Species of Pengornithidae (Aves: Enantiornithes) from the Lower Cretaceous of China Suggests a Specialized Scansorial Habitat Previously Unknown in Early Birds". PLOS ONE. 10 (6): e0126791.

Kaye TG, Pittman M, Marugán-Lobón J, Martín-Abad H, Sanz JL and Buscalioni AD 2019. Fully fledged enantiornithine hatchling revealed by Laser-Stimulated Fluorescence supports precocial nesting behavior. Nature.com/scientific reports (2019) 9:5006 https://doi.org/10.1038/s41598-019-41423-7

Knoll, F. et al. (16 co-authors) 2018. A diminutive perinate European Enantiornithes reveals an asynchronous ossification pattern in early birds. Nature Communications 9, 93.

O’Connor JK, Wang X-L, Zheng X-T, Hu H, Zhang X-M and Zhou Z 2016.
An Enantiornithine with a Fan-Shaped Tail, and the Evolution of the Rectricial Complex in Early Birds.Current Biology (advance online publication) DOI: http://dx.doi.org/10.1016/j.cub.2015.11.036

O'Connor JK, Falk A, Wang M and Zheng X-T 2020. First report of immature feathers in juvenile enantiornithines from the Early Cretaceous Jehol avifauna. Vertebrata PalAsiatica 58(1):24–44. DOI: 10.19615/j.cnki.1000-3118.190823

Wang M, O'Connor JK, Zhao T, Pan Y, Zheng X, Wang X and Zhou Z 2021. An Early Cretaceous enantiornithine bird with a pintail. Current Biology. http://doi:10.1016/j.cub.2021.08.044

Wang M, Stidham TA, O'Connor JK and Zhou Z 2022. Insight into the evolutionary assemblage of cranial kinesis from a Cretaceous bird. eLife2022;11:e81337. DOI: https://doi.org/10.7554/eLife.81337

Wang et al (6 co-authors 2024. First Edentulous Enantiornithine (Aves: Ornithothoraces) from the Lower Cretaceous Jehol Avifauna Cretaceous Research https://doi.org/10.1016/j.cretres.2024.105867

Zhou Z, Clarke J, Zhang F 2008. Insight into diversity, body size and morphological evolution from the largest Early Cretaceous enantiornithine bird. Journal of Anatomy 212: 565–577.

wki/Pengornis
wki/Chiappeavis
wiki/Gretcheniao
wiki/Parapengornis
wiki/Bohaiornis
wiki/Shenqiornis
wiki/Yuanchuavis
wiki/Imparavis