Yanornis martini holotype (IVPP V12558, Zhou and Zhang 2001; Early Cretaceous) is a taller tiny bird nesting between Changzuiornis (above) and Gansus (below).

Juehuaornis zhangi (Wang et al. 2015; Early Cretaceous, 122mya; SJG 00001) is a tiny toothless crane mimic basal to derived toothed Cretaceous birds. A long rostrum 70% of the skull length?cranial end of upper jaw hooked?and cranial end of lower jaw straight.

Changzuiornis ahgm (Huang et al. 2016; Early Cretaceous) nests between Juehuaornis ()above) and Hesperornis (below).

Ichthyornis dispar (Marsh 1872) Late Cretaceous ~90 mya, 24 cm in length, wingspan 43 cm was a deep-breasted, tern-like flying bird derived Apsaravis.

Like outgroup taxa, the skull of Ichthyornis had a long rostrum with teeth largely missing from the anterior half of the upper rostrum. The premaxilla was extended to form a sharper tip. The naris was larger than the antorbital fenestra. Several cranial bones fused to one another or disappeared.

The cervicals increased in number and decreased in size, creating a longer, more flexible neck. The dorsals were reduced in number. The sacrals were coosified into a sacrum. The caudal vertebrae were fused to form a pygostyle from which the tail feathers fanned out. The dorsal ribs were elongated and tied together with short uncinate processes. The sternal ribs extended to below the acetabulum. The pubis was further rotated posterior such that it paralleled the posteriorly rotated ischium. The femur was shortened, no longer deeper than the torso.

Benito et al (5 co-authors) 2022. Forty new specimens of Ichthyornis provide unprecedented insight into the postcranial morphology of crownward stem group birds. PeerJ 10:e13919 DOI 10.7717/peerj.13919

Clarke JA and Norell MA 2002. The morphology and phylogenetic position of Apsaravis ukhaana from the Late Cretaceous of Mongolia. American Museum Novitates 3387:46 pp.

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.

Huang J, Wang X, Hu Y-C, Liu J, Peteya JA and Clarke JA 2016. A new ornithurine from the Early Cretaceous of China sheds light on the evolution of early ecological and cranial diversity in birds. PeerJ.com

Marsh OC 1872. Notice of a new and remarkable fossil bird. American Journal of Science
4(61):344–380 DOI 10.1080/00222937308696770.

Marsh, OC 1880. Odontornithes, a Monograph on the Extinct Toothed Birds of North America. Government Printing Office, Washington DC.

Martin L 1984. A new Hesperornithid and the relationships of the Mesozoic birds. Transactions of the Kansas Academy of Science 87:141-150.

Norell MA and Clarke JA 2001. Fossil that fills a critical gap in avian evolution. Nature 409:181–184.

Wang R-F, Wang Y and Hu Dong-yu 2015. Discovery of a new ornithuromorph genus, Juehuaornis gen. nov. from Lower Cretaceous of western Liaoning, China. Global Geology 34(1):7-11.

Zhou Z. and Zhang F. 2001. Two new ornithurine birds from the Early Cretaceous of western Liaoning, China. Chinese Science Bulletin, 46 (15), 1258-1264.

Zhang F and Zhou Z 2001. A Primitive Enantiornithine Bird and the Origin of Feathers. Science 290 (5498): 1955-1959.

wiki/Yanornis
wiki/Juehuaornis
wiki/Apsaravis
wiki/Ichthyornis
wiki/Changzuiornis