Oviraptorid dinosaurs from southern China

Heyuannia huangi Lu, 2003 from the Late Cretaceous of Southern China is described in detail. The revised diagnosis of Heyuannia huangi includes the following characters: quadratojugal articular surface of the quadrate groove-like, the quadrate diverticulum entering the quadrate anterolaterally, metacarpal I wrapped around metacarpal II proximally, pneumatic foramina present on the neural arches and ribs of cervical vertebrae, the angle between the scapula and coracoid approximately 145°, the ratio of coracoid length to scapular length approximately 0.35, the pubis as long as ischium, and the ratio of femur length to tibia length 0.8. Two new oviraptorids from the Nanxiong Basin are also described. A phylogenetic analysis was carried out in two parts. The first phylogenetic analysis is to test the systematic position of Oviraptorosauria among ceolurosaurid dinosaurs. This analysis shows that Oviraptorosauria form a monophyletic group. Incisivosaurus gauthieri is the most basal oviraptorosaur and Caudipteryx is the second most primitive form. Alvarezsauridae is a sister group to TO (Therizinosauriodea and Oviraptorosauria). Within this more inclusive analysis (among Ceolurosauria), all the derived forms of Oviraptorosauria (excluding the primitive forms such as Incisivosaurus gauthieri and Caudipteryx zoui) form an unresolved polytomy. The second analysis is to determine the interrelationships among oviraptorosaurs. This less inclusive analysis (only a few groups of Ceolurosauria were employed for analysis) allows better resolution within Oviraptorosauria. The analysis shows that all oviraptorosaurs form a monophyletic group, Incisivosaurus gauthieri is the most basal oviraptotosaur, Caudipteryx zoui is the second most primitive form and Avimimus portentosus is basal to the derived oviraptorosaurs. The two new taxa from Nanxiong Basin are not nested within same clade. Shixinggia oblita may be the first caenagnathid oviraptorosaur found from southern China.; Some small maniraptoran dinosaurs independently acquire avian characters, including Microraptor zhaoianus, Microraptor gui (basal dromaeosaurids), Caudipteryx zoui (a basal oviraptorosaur), Sinovenator changii (a basal troodontid), Beipiaosaurus inexpectus (therizinosaur) and alvarezsaurids. The derived oviraptorosaurs independently attained more avian characters both in the skull and postcranial skeleton than other theropod dinosaurs did. Some of the morphologies present in derived oviraptorosaurs parallel modern ratites.