A new Lower Cretaceous bird from China and tooth reduction in early avian evolution

Abstract

A new avian genus and species, Zhongjianornis yangi gen. et sp. nov., is reported from the Lower Cretaceous lacustrine deposits of the Jiufotang Formation in Liaoning, northeast China. The new taxon is characterized by possessing the following combination of features: upper and lower jaws toothless, snout pointed, humerus with large and robust deltopectoral crest, second phalanx of the major manual digit longer than the first phalanx, unguals of the alular and major digits of similar length and significantly shorter than the corresponding penultimate phalanges, tibiotarsus slender and more than twice the length of the tarsometatarsus, and metatarsal IV longer than the other metatarsals. Phylogenetic analysis indicates that Zhongjianornis is phylogenetically basal to Confuciusornis and the dominant Mesozoic avian groups, Enantiornithes and Ornithurae, and therefore provides significant new information regarding the diversification of birds in the Early Cretaceous. It also represents the most basal bird that completely lacks teeth, suggesting that tooth loss was more common than expected in early avian evolution and that the avian beak appeared independently in several avian lineages, most probably as a response to selective pressure for weight reduction. Finally, the presence of a significantly enlarged humeral deltopectoral crest suggests that Zhongjianornis shares with other basal birds such as Jeholornis, Sapeornis and Confuciusornis a distinctive mode of adaptation for flight contrasting with that seen in more advanced birds, which instead possess an elongated sternum and a prominent keel.

Pre‐modern Birds: Avian Divergences in the Mesozoic

“…The basal placement of Archaeorhynchus within Ornithuromorpha has been supported by previous analyses Zhou et al, 2010). Basal ornithuromorphs are not resolved, and Apsaravis is included in this polytomy despite some previous analyses that have suggested this taxon is more derived (Clarke et al, 2006;You et al, 2006;.…”

“…Most past analyses have placed Ichthyornis closer to modern birds than Hesperornis (Chiappe, 2002a;Clarke, 2004;You et al, 2006;Zhou et al, 2010). This study includes a comprehensive review of the anatomy of Hesperornithiformes and thus may be a more accurate assessment of the relationships of these taxa.…”

Evolution of olfaction in non-avian theropod dinosaurs and birds

“…Consequently, the phylogenetic position of the extinct birds had to be inferred from previous morphological phylogenetic analyses. The phylogenetic position of Presbyornis and basal birds was readily determined using published morphological analyses [83,84]. The phylogenetic placement of the extinct genus Lithornis, however, was problematic owing to differences in tree topology between morphological and molecular phylogenies for palaeognaths and because of the variable position of Lithornis in morphological phylogenies (i.e.…”

Objects prompt authentic scientific activities among learners in a museum programme

“…This is advantageous in flight because it reduces drag and energy expenditure, but also because it reduces the part of modern bird's body weight that is far from its centre of gravity (cf. Zhou & Li, 2010). Accordingly, Archaeopteryx' long tail is interpreted as a contraindication of flight capability (Table 1, …”