Xinghaiornis lini (Aves: Ornithothoraces) from the Early Cretaceous of Liaoning: An Example of Evolutionary Mosaic in Early Birds

Abstract

We describe a new species of Early Cretaceous bird from the Yixian Formation of Liaoning Province. Xinghaiornis lini gen. et sp. nov. is relatively large and characterized by a long, toothless rostrum and an elevated pedal digit I. The design of the skull and feet suggests that this bird was likely a mud‐prober. This discovery provides strong support indicating that this avian trophic specialization originated at least 125 million years ago.

Quantitative Analysis of Morphometric Data of Pre-modern Birds: Phylogenetic Versus Ecological Signal

“…This analysis identified a variety of trophic guilds among early birds, including granivores (e.g., Jeholornis, Sapeornis), piscivores (e.g., Yanornis), and birds that fed on invertebrates (Eoalulavis) (O 'Connor 2019). The elongate, thin rostrum and mandible of Longirostravis (Hou et al, 2004) and Xinghaiornis (Wang et al, 2013) has been used to infer a shoredwelling, mud-probing lifestyle for both these birds.…”

“…The study in question, however, focused exclusively on the Jehol Biota and used a very limited number of taxa from that assemblage. A number of studies have posited a trophic bias among Early Cretaceous birds, with gut contents, facial morphology, tooth patterns and form, and other indicators of diet or ecological niche suggesting that many enantiornithines from this time period may have had an arboreal lifestyle and an insectivorous diet (although there are notable counterexamples among the longipterygids; see O 'Connor et al, 2011), while ornithuromorphs are more commonly interpreted as landdwellers or amphibious birds that ate fish or probed the substrate in search of crustaceans and worms (Zhou 2006;Wang et al, 2013;Field et al, 2018;O'Connor 2019;Wang et al, 2020). These generalizations, however, are far from certain, and to date quantitative data has not been used to test these observations.…”

New Information on the Keratinous Beak of Confuciusornis (Aves: Pygostylia) From Two New Specimens

“…Tooth loss is far more common in the enantiornithine sister-clade the Ornithuromorpha, the clade that includes modern birds nested within (O'Connor et al, 2011). Several Early Cretaceous ornithuromorphs preserve edentulous rostra: Archaeorhynchus (Zhou and Zhang, 2006;Zhou et al, 2013), Eogranivora (Zheng et al, 2018), Xinghaiornis (Wang et al, 2013), Schizooura (Zhou et al, 2012), and Dingavis (O'Connor et al, 2016). The phylogenetic distribution of these taxa strongly suggests that tooth loss most likely evolved independently in each lineage and thus numerous times in this clade alone (O'Connor et al, 2016;.…”