Epidexipteryx

Epidexipteryx ("display feather") is a genus of small paravian dinosaurs, known from one fossil specimen in the collection of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing. Epidexipteryx represents the earliest known example of ornamental feathers in the fossil record.[1] The type specimen is catalog number IVPP V 15471. It has been reported to be a maniraptoran dinosaur from the Middle Jurassic or Upper Jurassic age Daohugou Beds of Inner Mongolia, China (about 160 or 168 mya).[2]

The specific name, Epidexipteryx hui ("Hu's display feather"), and its Chinese name Hushi Yaolong ("Hu Yaoming's dragon") were coined in memory of paleomammologist Hu Yaoming.

History of publication
Due to a pre-publication error,[4] a manuscript of the Epidexipteryx hui description first appeared on a preprint Web portal in late September, 2008. The paper was officially published in the October 23rd, 2008, issue of the journal Nature.

Taxonomy and systematics
The exact phylogenetic position of Epidexipteryx within Paraves is uncertain. The phylogenetic analysis conducted by the authors of its description recovered it as a member of the family Scansoriopterygidae and as a basal member of the clade Avialae;[2] this was confirmed by the subsequent analysis conducted by Hu et al. (2009).[5] A later analysis conducted by Agnolín and Novas (2011) confirmed it to be a scansoriopterygid, but recovered a different phylogenetic position of this family: Scansoriopterygidae was recovered in polytomy with the family Alvarezsauridae and the clade Eumaniraptora (containing the clades Avialae and Deinonychosauria).[6] Turner, Makovicky and Norell (2012) included Epidexipteryx but not Scansoriopteryx/Epidendrosaurus in their primary phylogenetic analysis, as a full-grown specimen is known only of the former taxon; regarding Scansoriopteryx/Epidendrosaurus, the authors were worried that including it in the primary analysis would be problematic, because it is only known from juvenile specimens, which "do not necessarily preserve all the adult morphology needed to accurately place a taxon phylogenetically" (Turner, Makovicky and Norell 2012, p. 89). Epidexipteryx was recovered as basal paravian that didn't belong to Eumaniraptora. The authors did note that its phylogenetic position is unstable; constraining Epidexipteryx hui as a basal avialan required two additional steps compared to the most parsimonious solution, while constraining it as a basal member of Oviraptorosauria required only one additional step. A separate exploratory analysis included Scansoriopteryx/Epidendrosaurus, which was recovered as a basal member of Avialae; the authors noted that it did not clade with Epidexipteryx, which stayed outside Eumaniraptora. Constraining the monophyly of Scansoriopterygidae required four additional steps and moved Epidexipteryx into Avialae.[7] A monophyletic Scansoriopterygidae was recovered by Godefroit et al. (2013); the authors found scansoriopterygids to be basalmost members of Paraves and the sister group to the clade containing Avialae and Deinonychosauria.[8] Agnolín and Novas (2013) recovered monophyletic Scansoriopterygidae as well, but found them to be non-paravian maniraptorans and the sister group to Oviraptorosauria.

An abbreviated version of Zhang et al.'s 2008 cladogram is presented below. {{clade|style=font-size:100%;line-height:80% }} }}
 * label1=Maniraptora
 * 1=
 * 1=Therizinosauroidea
 * label2= unnamed
 * 2={{clade
 * 1=Alvarezsauridae
 * 2=Oviraptorosauria
 * label2= unnamed
 * 2={{clade
 * label1= unnamed
 * 1={{clade
 * 1=Troodontidae
 * 2=Dromaeosauridae
 * label2=Avialae|2={{clade
 * label1=Scansoriopterygidae
 * 1={{clade
 * 1=Scansoriopteryx (=Epidendrosaurus)
 * 2=Epidexipteryx