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Main » 2008 » July » 17 » A NEW BASAL LINEAGE OF EARLY CRETACEOUS BIRDS FROM CHINA AND ITS IMPLICATIONS ON THE EVOLUTION OF THE AVIAN TAIL
A NEW BASAL LINEAGE OF EARLY CRETACEOUS BIRDS FROM CHINA AND ITS IMPLICATIONS ON THE EVOLUTION OF THE AVIAN TAIL
05:58
We report on a new Early Cretaceous bird from China that sheds significant light on the evolutionary transition between primitive birds with a long bony tail and those with a short tail ending in a pygostyle. A cladistic analysis of basal birds supports the placement of the new fossil as the sister-taxon of all pygostylians. Possessing a unique hand morphology with a phalangeal formula of 2-3-3-x-x and a reduced number of caudal vertebrae lacking a pygostyle, the new specimen reveals anatomical information previously unknown and increases the taxonomic diversity of primitive, non-pygostylian birds. We infer from the specimen that during the evolution of the avian tail, a decrease in relative caudal length and number of vertebrae preceded the distal fusion of caudals into a pygostyle.

Holotype of Zhongornis haoae (D2455 . 6). Photographs of the slab (left; D2456) and counterslab (right; D2455) under normal light.
Interpretive drawing of slab (some portions added from information contained in counterslab) with close-ups of the manus, foot and caudal vertebrae. Abbreviations: co, coracoid; cv, caudal vertebrae (c1–c13); cve, cervical vertebrae; dc, distal carpal;
dpc, deltopectoral crest; dv, dorsal vertebrae; gas, gastralia; f, frontal; fei, feather impressions; fem, femur; fib, fibula; fur, furcula; hum, humerus; isc, ischium; j, jugal; mcI–III, metacarpals I–III; mtI–IV, metatarsals I–IV; pmx, premaxilla; q, quadrate; rad, radius; rib, thoracic ribs; sc, scapula; syn, synsacrum; tib, tibia; uln, ulna; I–IV, digits (manual or pedal) I–IV.
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