Euornithes

Euornithes Temporal range: Early Cretaceous–Holocene, 128–0Ma PreꞒ Ꞓ O S D C P T J K Pg N
Fossil specimen of Hongshanornis longicresta
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Pygostylia
Clade:	Ornithothoraces
Clade:	Euornithes Cope, 1889
Subgroups
†Archaeorhynchus Ornithuromorpha †Ambiortiformes †Gansuiformes †Yanornithiformes Ornithurae And see text

Euornithes (meaning "true birds" in Greek) is the name of a natural group which includes the most recent common ancestor of all avialans closer to modern birds than to Sinornis.

Description

Clarke at al. (2006) found that the most primitive known euornithians (the Yanornithiformes) had a mosaic of advanced and primitive features. These species retained primitive features like gastralia (belly ribs) and a pubic symphysis. They also showed the first fully modern pygostyles, and the type specimen of Yixianornis (IVPP 13631) preserves eight elongated rectrices (tail feathers) in a modern arrangement. No earlier pygostylians are known which preserve a fan of tail feathers of this sort; instead, they show only paired plumes or a tuft of short feathers.^[1]

Classification

The name Euornithes has been used for a wide variety of avialan groups since it was first named by Edward Drinker Cope in 1889. It was first defined as a clade in 1998 by Paul Sereno, who made it the group of all animals closer to birds than to Enantiornithes (represented by Sinornis). This definition currently includes similar content as another widely used name, Ornithuromorpha, named and defined by Luis Chiappe in 1999 as the common ancestor of Patagopteryx, Vorona, and Ornithurae, plus all of its descendants. Because one definition is node-based and the other branch-based, Ornithuromorpha is a slightly less inclusive group. Several studies published in 2013 found that of currently known species, the only euornithine that is not within the Vorona and Patagopteryx group is Archaeorhynchus.^[2][3]

Genera

The following is a list of primitive euornithian genera and those that cannot be confidently referred to any subgroups, following Holtz (2011) unless otherwise noted.^[4]

• †Alamitornis
• †Ambiortus
• †Archaeorhynchus
• †Changmaornis^[5]
• †Chaoyangia
• †Gargantuavis
• †Holbotia
• †Hollanda
• †Horezmavis
• †Hulsanpes?
• †Jianchangornis
• †Jiuquanornis ^[5]
• †Limenavis
• †Patagopteryx
• †Piscivoravis^[3]
• †Platanavis
• †Schizooura
• †Vorona
• †Wyleyia?
• †Yumenornis^[5]
• †Xinghaiornis?^[6]
• †Zhongjianornis
• †Zhyraornis

Note that Holtz also included the genera Eurolimnornis and Piksi as euornitheans, though they have since been re-identified as pterosaurs.^[7]

Phylogeny

The cladogram below follows O’Connor et al., 2013 phylogenetic analysis. The clade names are positioned based on their definitions (contra O’Connor et al. (2013)).^[8]

References