Archaeopteryx and the Origin of Flight

Ostrom, John H.

doi:10.1086/407902

Cited by 213 publications

(134 citation statements)

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“…The discovery of Archeopteryx (145 mya) in Germany and other fossils led to the compelling Dinosaur-bird hypothesis, suggesting that birds evolved from the dinosaur (Ostrom, 1974). Dinosaurs began flourishing in the Late Triassic, about 215 mya, and dominated the earth for the next 150 million years (Sereno, 1999).…”

Section: Feathered Dinosaurs?mentioning

confidence: 99%

Adaptation to the sky: Defining the feather with integument fossils from mesozoic China and experimental evidence from molecular laboratories

Chuong

Zhang

et al. 2003

J Exp Zool Pt B

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In this special issue of Evo-Devo of the amniote integument, Alibardi has discussed the adaptation of the integument to the land. Here we will discuss the adaptation to the sky. We first review a series of fossil discoveries representing intermediate forms of feathers or feather-like appendages from dinosaurs and Mesozoic birds from the Jehol Biota of China. We then discuss results from the molecular and developmental biological experiments using chicken integument as the model. Feather forms can be modulated using retrovirus mediated gene mis-expression that mimics those found in nature today and in the evolutionary past. The molecular conversions among different types of integument appendages (feather, scale, tooth) are discussed. From these evidences, we recognize that not all organisms with feathers are birds, and that not all skin appendages with hierarchical branches are feathers. We develop a set of criteria for true avian feathers: 1) possessing actively proliferating cells in the proximal follicle for a proximo -distal growth mode; 2) forming hierarchical branches of rachis, barbs and barbules, with barbs shaped by differential cell death into either bilaterally or radially symmetric structures; 3) having a follicle structure, with a mesenchyme core during development; 4) maturing into a structure consisting of epithelia without a mesenchyme core with two sides of the vane facing the previous basal and supra-basal layer, respectively; and 5) having stem cells and dermal papilla in the follicle and hence the ability to molt and regenerate. A model of feather evolution from feather bud → barbs → barbules → rachis is presented, which is opposite to the old view of scale plate → rachis → barbs → barbules.

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Section: Feathered Dinosaurs?mentioning

confidence: 99%

Adaptation to the sky: Defining the feather with integument fossils from mesozoic China and experimental evidence from molecular laboratories

Chuong

Zhang

et al. 2003

J Exp Zool Pt B

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“…This evidence shows that the protoavian was arboreal (1) rather than a terrestrial cursor as many have suggested (2)(3)(4). The leading protagonist in this controversy is presently a dromaeosaur, Microraptor gui, with a fully formed hind wing that is closely similar to its completely avian forewing (5), having elongate, aerodynamically advanced "primary feathers" coming off the metatarsi (5).…”

mentioning

confidence: 94%

Model tests of gliding with different hindwing configurations in the four-winged dromaeosaurid Microraptor gui

Alexander

Gong

Martin

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

102

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Fossils of the remarkable dromaeosaurid Microraptor gui and relatives clearly show well-developed flight feathers on the hind limbs as well as the front limbs. No modern vertebrate has hind limbs functioning as independent, fully developed wings; so, lacking a living example, little agreement exists on the functional morphology or likely flight configuration of the hindwing. Using a detailed reconstruction based on the actual skeleton of one individual, cast in the round, we developed light-weight, three-dimensional physical models and performed glide tests with anatomically reasonable hindwing configurations. Models were tested with hindwings abducted and extended laterally, as well as with a previously described biplane configuration. Although the hip joint requires the hindwing to have at least 20°of negative dihedral (anhedral), all configurations were quite stable gliders. Glide angles ranged from 3°to 21°with a mean estimated equilibrium angle of 13.7°, giving a lift to drag ratio of 4.1:1 and a lift coefficient of 0.64. The abducted hindwing model's equilibrium glide speed corresponds to a glide speed in the living animal of 10.6 m·s −1 . Although the biplane model glided almost as well as the other models, it was structurally deficient and required an unlikely weight distribution (very heavy head) for stable gliding. Our model with laterally abducted hindwings represents a biologically and aerodynamically reasonable configuration for this four-winged gliding animal. M. gui's feathered hindwings, although effective for gliding, would have seriously hampered terrestrial locomotion.E vidence now exists that should settle the long-running debate over a ground-up origin of avian flight vs. the evolution of avian flight from a trees-down glider. This evidence shows that the protoavian was arboreal (1) rather than a terrestrial cursor as many have suggested (2-4). The leading protagonist in this controversy is presently a dromaeosaur, Microraptor gui, with a fully formed hind wing that is closely similar to its completely avian forewing (5), having elongate, aerodynamically advanced "primary feathers" coming off the metatarsi (5). There seems little reason to doubt the aerodynamic function of the hindwing, but there has been controversy over exactly how it was arranged and used for flight. We decided to address this problem by creating and testing models that closely replicate the anatomical features preserved in the now numerous fossils of Microraptor and its close relatives (discussed in SI Text).Primitively, early archosaurs are sprawling, with the legs set laterally and elevated at around 75°(6), a preadapted posture for gliding. Modern birds normally have the thigh elevated and sprawled to the side in different degrees; for example, it is nearly perpendicular to the midline in loons and grebes (7). This variation shows that the degree of splaying needed to use the hindlegs in gliding is not unusual when compared with that in modern birds. The absence of an antitrochanter and a supraacetabular shelf (SAC) i...

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“…Indeed, for all three main hypotheses proposed for the origin of flight in birds, a transition between the substrate and the air is necessary before any kind of flight is accomplished, regardless of the substrate from which takeoff occurs. These hypotheses include the traditional 'arboreal versus cursorial' origins (Ostrom, 1974;Padian, 1987) and an alternative hypothesis involving wing-assisted incline running (Dial, 2003). Thus, the debate about the origin of flight is closely linked to the ability to perform an effective take-off, and thus also to the contributions and coordination of the forelimbs and hindlimbs during this phase.…”

Section: Introductionmentioning

confidence: 99%

Transition from leg to wing forces during take-off in birds

Provini

Tobalske

Crandell

et al. 2012

Journal of Experimental Biology

106

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SUMMARYTake-off mechanics are fundamental to the ecology and evolution of flying animals. Recent research has revealed that initial takeoff velocity in birds is driven mostly by hindlimb forces. However, the contribution of the wings during the transition to air is unknown. To investigate this transition, we integrated measurements of both leg and wing forces during take-off and the first three wingbeats in zebra finch (Taeniopygia guttata, body mass 15g, N7) and diamond dove (Geopelia cuneata, body mass 50g, N3). We measured ground reaction forces produced by the hindlimbs using a perch mounted on a force plate, whole-body and wing kinematics using high-speed video, and aerodynamic forces using particle image velocimetry (PIV). Take-off performance was generally similar between species. When birds were perched, an acceleration peak produced by the legs contributed to 85±1% of the whole-body resultant acceleration in finch and 77±6% in dove. At lift-off, coincident with the start of the first downstroke, the percentage of hindlimb contribution to initial flight velocity was 93.6±0.6% in finch and 95.2±0.4% in dove. In finch, the first wingbeat produced 57.9±3.4% of the lift created during subsequent wingbeats compared with 62.5±2.2% in dove. Advance ratios were <0.5 in both species, even when taking self-convection of shed vortices into account, so it was likely that wing-wake interactions dominated aerodynamics during wingbeats 2 and 3. These results underscore the relatively low contribution of the wings to initial take-off, and reveal a novel transitional role for the first wingbeat in terms of force production. Supplementary material available online at

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Archaeopteryx and the Origin of Flight

Cited by 213 publications

References 0 publications

Adaptation to the sky: Defining the feather with integument fossils from mesozoic China and experimental evidence from molecular laboratories

Adaptation to the sky: Defining the feather with integument fossils from mesozoic China and experimental evidence from molecular laboratories

Model tests of gliding with different hindwing configurations in the four-winged dromaeosaurid Microraptor gui

Transition from leg to wing forces during take-off in birds

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