Pedopenna 2838050 219787012 2008-06-16T21:38:38Z Dionea 318970 /* Description */ fix misdirected wiki link {{Taxobox | name = ''Pedopenna'' | fossil_range = [[Middle Jurassic|Mid]]-[[Late Jurassic]]? | image = Pedopenna.jpg | image_width = 250px | image_caption = | regnum = [[Animal]]ia | phylum = [[Chordate|Chordata]] | classis = [[Reptile|Sauropsida]] | superordo = [[Dinosaur]]ia | ordo = [[Saurischia]] | subordo = [[Theropoda]] | unranked_familia = [[Maniraptora]] | genus = '''''Pedopenna''''' | genus_authority = [[Xu Xing|Xu]] & Zhang, 2005 | subdivision_ranks = [[Species]] | subdivision = '''''P. daohugouensis''''' <small>Xu & Zhang, 2005</small> }} '''''Pedopenna''''' ("foot feather") is a [[genus]] of small, feathered, [[maniraptora]]n [[dinosaur]] from the [[Daohugou Beds]] in [[China]]. It is possibly older than ''[[Archaeopteryx]]'', though the age of the [[Daohugou Beds]] where it was found is debated. Some estimates give an [[Early Cretaceous]] age, but the latest radiometric dating shows them to be late [[Middle Jurassic]] ([[Callovian]]) (c.140-168 [[mya (unit)|mya]]<!-- ChinSciBull 50(20):2369-2376: [[Epidendrosaurus#_note-Wangetal06]] -->). The name ''Pedopenna'' refers to the long pennaceous feathers on the metatarsus; ''daohugouensis'' refers to the locality of Daohugou, where the [[holotype]] was found. ''Pedopenna daohugouensis'' probably measured 1&nbsp;[[metre|meter]] (3&nbsp;[[foot (unit of length)|ft]]) or less in length, but since this species is only known from the hind legs, the actual length is difficult to estimate. ''Pedopenna'' is classified as a [[Deinonychosauria|paravian]] ([[Paraves]]), the group of [[maniraptora]]n dinosaurs that includes [[Aves]] and their closest relatives. == Description == The feet of ''Pedopenna'' resembled those of the related [[troodontid]]s and [[dromaeosaurid]]s (which together form the group [[Deinonychosauria]]), though were overall more primitive. In particular, the second toe of ''Pedopenna'' was not as specialized as in deinonychosaurs. While ''Pedopenna'' did have an enlarged claw and slightly shortened second toe, it was not as highly developed as the strongly curved, sickle-like claws of its relatives. Xu and Zhang, who interpreted the [[Daohugou Beds|Daohugou]] fossil beds where ''Pedopenna'' was found as mid to late [[Jurassic]] in age, used the presence of such a primitive member of the avian lineage, in combination with many primitive members of closely related lineages there, to support the idea that birds originated in [[Asia]]. ===Feathers=== The avian affinities of ''Pedopenna'' are further evidence of the dinosaur-bird evolutionary relationship. Apart from having a very bird-like skeletal structure in its legs, ''Pedopenna'' was remarkable due to the presence of long pennaceous [[feather]]s on the [[metatarsus]] (foot). Some deinonychosaurs are also known to have these 'hind wings', but those of ''Pedopenna'' differ from those of animals like ''[[Microraptor]]''. ''Pedopenna'' hind wings were smaller and more rounded in shape. The longest feathers were slighlty shorter than the metatarsus, at about 55mm (2 in) long. Additionally, the feathers of ''Pedopenna'' were symmetrical, unlike the asymmetrical feathers of some deinonychosaurs and birds. Since asymmetrical feathers are typical of animals adapted to flying, it is likely that ''Pedopenna'' represents an early stage in the development of these structures. While many of the feather impressions in the fossil are weak, it is clear that each possessed a rachis and barbs, and while the exact number of foot feathers is uncertain, they are more numerous than in the hind-wings of ''Microraptor''. ''Pedopenna'' also shows evidence of shorter feathers overlying the long foot feathers, evidence for the presence of [[covert_(feather)|covert]]s as seen in modern birds. Since the feathers show fewer aerodynamic adaptations than the similar hind wings of ''Microraptor'', and appear to be less stiff, suggests that if they did have some kind of aerodynamic function, it was much weaker than in deinonychosaurs and birds. Xu and Zhang, in their 2005 description of ''Pedopenna'', suggested that the feathers could be ornamental, or even vestigial. It is possible that a hind wing was present in the ancestors of deinoychosaurs and birds, and later lost in the bird lineage, with ''Pedopenna'' representing an intermediate stage where the hind wings are being reduced from a functional gliding apparatus to a display or insulatory function. == References == * Xu, X., and Zhang, F. (2005). "A new maniraptoran dinosaur from China with long feathers on the metatarsus." ''Naturwissenschaften'', '''92'''(4): 173 - 177. {{portalpar|Dinosaurs}} [[Category:Dinosaurs of Asia]] [[Category:Coelurosaurs]] [[Category:Feathered dinosaurs]] [[Category:Jurassic dinosaurs]] [[cs:Pedopenna]] [[es:Pedopenna]] [[nl:Pedopenna]] [[pl:Pedopenna]] [[sv:Pedopenna]] [[zh:足羽龍]]