A New Discovery Of Anchiornis From Western Of Liaoning,China

Over ten years recently, the continuously unearthed new dinosaur materials in China greatly enrich the dinosaur genealogy. Especially the discoveries of many feathered dinosaur fossils have not only lent strongest support for the dinosaurian hypothesis of bird origins, but have also significantly advanced our understanding of the origin and early evolution of feathers, though admittedly still much information is needed to understand some critical stages for feather evolution. And the discoveries of these specimens with feather impressions both in theropods and ornithopods can trace the origin and initial funtion of feathers to tens of million years before, which strongly supports the hypothesis that feathers evolved and initially diversified in nonavian theropods before the origin of birds and the evolution of ?ight. Miroraptor and Anchiornis with four wing structure implicate that the evolution of flight is a complex process and experiences a four-winged stage. Fossils of Limusaurus with a strongly reduced manual digit I suggest the complex pattern of digital reduction within the Theropoda. Xu Xing et al. proposed that the transition to tetanurans involved complex changes in the hand including a shift in digit identities, which helps clarify avian digital homologies. Recent discovery of Linhenykus monodactylus with only digit II in the hand points to a complex mosaic pattern of manual evolution in alvarezsauroids. This paper uses the newly II-III-IV manus model, comparing to the old I-II-III manus model.As lots of nonavian theropod fossils have been discovered, new achievements and progresses are being updating. The author decided to take a statistical work of recent achivements and significant progresses of dinosaur researches, and based on this collection work, translation and refining of the diagnosic features between different theropods is done, which is showed on tabular form.This paper systematically describes a new member of Anchiornis: Anchiornis jianchangensis sp. nov. The specimen preserved by left lateral view, except for only left scapular, left coracoid and left ilium preserved, containing almost complete skeletons, is an interrelated skeleton with all bones preserved in situ. This specimen has feather impressions in neck, back, abdomen, left forelimb, right hindlimb and tail. The difference of the feathers between different parts is notable. Feather types include filamentous feather, clusters of plumulaceous feathers and pennaceous feathers. The specimen is about 462mm long from the rostral skull to last preserved caudal, including the tail (243mm long) occupying about 53% of body length. Forelimb accounts for about 81% the length of hindlimb, manus accounts for about 46% the length of forelimb, tibia accounts for about 150% of femoral length and ischium accounts for about 31% of the femoral length. The fusion degree and proportions of the bones indicate that A.jianchangensis sp. nov. is a sub-adult individual. The specimen possesses a few Anchiornis features, including unserrated tooth, extremely shortness of ischium, straight ulnar shaft slightly wider than radius, extremely elongated tibiotarsus which measures about 150% of the femoral length, etc. Diagnosic features of the new species include: vertebrae colum is 10-13-4-33 which is different from that of A.huxleyi, slender ilium has a anteracetabular process without ventral process, postacetabular process is about 2.3 times as long as anteracetabular, pubic foot expands only in the posterior direction, hindlimb has no arctometatarsalian condition as in some dromaeosaurids.Troodontidae was recently defined as a stem-based taxon comprising all taxa that are closer to Troodon formosus than to Velociraptor mongoliensis. So far, Troodontidae has 14 species of 13 genera and an unnamed species (excluding this new species), and its systematic relationships are better known along with the new members unearthed and deeper researches achieved. This paper divides the published troodontid systematic relationships into five categories and the author puts forward his own understanding. Adding the new member of troodontids, Anchiornis jianchangensis sp. nov., cladistic systematics displays that Therizinosauridae and Oviraptorosauria are sister taxa and they have further relationship to Alvarezsauridae. Within the toodontid interrelationships, Sinovenator, Mei and Anchiornis show relatively independent evolutionary trend, they and other members of Troodontidae compose a monophyletic taxon which represents four directions toward troodontid systematic evolution.