Theropod Diversity and the Refinement of Avian Characteristics

Makovicky, Peter J.; Zanno, Lindsay E.

doi:10.1002/9781119990475.ch1

Cited by 45 publications

(47 citation statements)

References 95 publications

(137 reference statements)

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“…Our results document two stages in the evolution of modern flight feather morphology, illustrating a previously undocumented transitional morphology during the early evolution of avian flight [1,39]. The origin of the modern flight feather-characterized by small barb angles in cutting-edge vanes and larger barb angles in trailing vanes-is coincident with the inferred origin of multiple flight-related features, such as the alula and an ossified sternal keel [40,41].…”

Section: (C) Mesozoic Stem Birdsmentioning

confidence: 73%

“…These features arose subsequent to the origin of other hypothesized flight-related specializations such as the elongation of the coracoid, the acquisition of a fused pygostyle and the initial acquisition of asymmetrical flight feathers themselves [4]. Thus, the gradual, stepwise evolution of modern avian flight feathers parallels a broader, protracted period of flight apparatus refinement along the avian stem [1,39]. Although the precise phylogenetic origin of modern powered flying ability will continue to be debated, resolving this persistent controversy will depend on detailed comparative investigations of the components of the avian flight apparatus, incorporating both relevant fossil paravians as well as a broad phylogenetic sample of crown birds.…”

Section: (C) Mesozoic Stem Birdsmentioning

confidence: 99%

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Barb geometry of asymmetrical feathers reveals a transitional morphology in the evolution of avian flight

2015

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The geometry of feather barbs (barb length and barb angle) determines feather vane asymmetry and vane rigidity, which are both critical to a feather's aerodynamic performance. Here, we describe the relationship between barb geometry and aerodynamic function across the evolutionary history of asymmetrical flight feathers, from Mesozoic taxa outside of modern avian diversity (Microraptor, Archaeopteryx, Sapeornis, Confuciusornis and the enantiornithine Eopengornis) to an extensive sample of modern birds. Contrary to previous assumptions, we find that barb angle is not related to vane-width asymmetry; instead barb angle varies with vane function, whereas barb length variation determines vane asymmetry. We demonstrate that barb geometry significantly differs among functionally distinct portions of flight feather vanes, and that cutting-edge leading vanes occupy a distinct region of morphospace characterized by small barb angles. This cutting-edge vane morphology is ubiquitous across a phylogenetically and functionally diverse sample of modern birds and Mesozoic stem birds, revealing a fundamental aerodynamic adaptation that has persisted from the Late Jurassic. However, in Mesozoic taxa stemward of Ornithurae and Enantiornithes, trailing vane barb geometry is distinctly different from that of modern birds. In both modern birds and enantiornithines, trailing vanes have larger barb angles than in comparatively stemward taxa like Archaeopteryx, which exhibit small trailing vane barb angles. This discovery reveals a previously unrecognized evolutionary transition in flight feather morphology, which has important implications for the flight capacity of early feathered theropods such as Archaeopteryx and Microraptor. Our findings suggest that the fully modern avian flight feather, and possibly a modern capacity for powered flight, evolved crownward of Confuciusornis, long after the origin of asymmetrical flight feathers, and much later than previously recognized.

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Section: (C) Mesozoic Stem Birdsmentioning

confidence: 73%

Section: (C) Mesozoic Stem Birdsmentioning

confidence: 99%

Barb geometry of asymmetrical feathers reveals a transitional morphology in the evolution of avian flight

2015

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“…Yet, Smith et al [5] could, at the time, say that, yes, the monograph has been cited (twelve times!). But upon examination at the time of Google Scholar, one finds that the only paleontologist among their group to do so was Makovicky in a scorching criticism [110]. Regardless, the James and Pourtless monograph remains among the most important, but totally ignored, detailed accounts on the subject ever written!…”

Section: Censorship Of Opposing Viewsmentioning

confidence: 99%

FANTASY VS REALITY: A Critique of Smith et al.'s Bird Origins

Feduccia¹

2016

TOOENIJ

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Adherents of the current orthodoxy of a derivation of birds from theropod dinosaurs, criticize the commentary by Feduccia (2013, Auk, 130) [1 -12] entitled "Bird Origins Anew" as well as numerous papers by Lingham-Soliar on theropod dermal fibers, using numerous mischaracterizations and misstatements of content, and illustrate their own misconceptions of the nature of the debate, which are here clarified. While there is general agreement with the affinity of birds and maniraptorans, the widely accepted phylogeny, advocating derived earth-bound maniraptorans giving rise to more primitive avians (i.e. Archaeopteryx), may be "topsyturvy." The current primary debate concerns whether maniraptorans are ancestral or derived within the phylogeny, and whether many maniraptorans and birds form a clade distinct from true theropods. Corollaries of the current scheme show largely terrestrial maniraptoran theropods similar to the Late Cretaceous Velociraptor giving rise to avians, and flight originating via a terrestrial (cursorial) "gravity-resisted," as opposed to an arboreal "gravity-assisted" model. The current dogma posits pennaceous flight remiges in earth-bound theropods having evolved in terrestrial theropods that never flew. As part of the orthodoxy, fully feathered maniraptorans such as the tetrapteryx gliders Microraptor and allies, are incorrectly reconstructed as terrestrial cursors, when in reality their anatomy and elongate hindlimb feathers would be a hindrance to terrestrial locomotion.The same is true of many early birds, exemplified by reconstruction of the arboreally adapted Confuciusornis as a terrestrial predator, part of the overall theropodan scheme of birds evolving from terrestrial dinosaurs, and flight from the ground up. Both sides of this contentious debate must be constantly aware that new fossil or even molecular discoveries on birds may change current conclusions.

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“…The results of James and Pourtless (2009) recover weak support for alternative hypotheses of avian origins including mostly unresolved clades comprising birds and other maniraptorans. However, those analyses are biased by egregious taxon and character sampling issues, incorrect character scorings, and illogical character state definitions that amount to rather acute data manipulation (Makovicky and Zanno 2011, Turner et al 2012, Brusatte et al 2014. No plausible, phylogenetically contextualized challenge to the hypothesis that birds are nested within Maniraptora exists.…”

Section: Theoretical and Methodological Misunderstandingsmentioning

confidence: 99%

“…If collagen fibers, which are composed of biodegradable protein, can indeed fossilize, then they would be expected to be present as disjunct, underlying structures in at least some of the softbodied Jehol specimens, alongside or in place of feathers. Furthermore, no fibers that might be misinterpreted as collagen have been identified in any of the hundreds of choristodere specimens found alongside Sinosauropteryx in coeval Chinese deposits (Makovicky and Zanno 2011).…”

Section: Anatomical and Evolutionary Misinterpretationsmentioning

confidence: 99%

Rhetoric vs. reality: A commentary on “Bird Origins Anew” by A. Feduccia

Smith

Chiappe

Clarke

et al. 2015

The Auk

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Birds are maniraptoran theropod dinosaurs. The evidence supporting the systematic position of Avialae as a derived clade within Dinosauria is voluminous and derived from multiple independent lines of evidence. In contrast, a paucity of selectively chosen data weakly support, at best, alternative proposals regarding the origin of birds and feathers. Opponents of the theory that birds are dinosaurs have frequently based their criticisms on unorthodox interpretations of paleontological data and misrepresentation of phylogenetic systematic methods. Moreover, arguments against the nested position of Avialae in Dinosauria have often conflated the logically distinct questions of avian origins, the evolution of flight, and the phylogenetic distribution of feathers. Motivated by a Perspectives article with numerous factual inaccuracies that recently appeared in The Auk, we provide a review of the full complement of facts pertaining to the avian origins debate and address the misplaced criticisms raised in that opinion paper. Keywords: evolution of flight, evolution of feathers, evolution of birds, Avialae, maniraptoran theropod dinosaurs, phylogenetic systematics Retórica vs. Realidad: Un comentario sobre ''Bird Origins Anew'' por A. Feduccia, Auk 130:1-12 RESUMEN Las aves son dinosaurios terópodos maniraptores. La evidencia que sustenta la posición sistemática de Avialae como un clado derivado dentro de Dinosauria es voluminosa y se deriva de múltiples líneas independientes de evidencia. En contraste, sólo escasos datos elegidos selectivamente sustentan débilmente propuestas alternativas sobre el origen de las aves y las plumas. Los opositores de la teoría de que las aves son dinosaurios frecuentemente han basado sus críticas en interpretaciones no ortodoxas de los datos paleontológicos y en la tergiversación de los métodos de la sistemática filogenética. Además, los argumentos en contra de la posición anidada de Avialae dentro de Dinosauria han confundido la distinción lógica de las preguntas sobre los orígenes de las aves, la evolución del vuelo y la distribución filogenética de las plumas. Motivados por un artículo de Perspectivas que apareció recientemente en The Auk con numerosas imprecisiones fácticas, presentamos una revisión del conjunto completo de hechos relacionados con el debate sobre el origen de la aves y abordamos las críticas equivocadas que se presentan en dicho artículo de opinión. Palabras clave: Avialae, dinosaurios terópodos maniraptores, evolución de las aves, evolución de las plumas, evolución del vuelo, sistemática filogenética Q 2015 American Ornithologists' Union.

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Theropod Diversity and the Refinement of Avian Characteristics

Cited by 45 publications

References 95 publications

Barb geometry of asymmetrical feathers reveals a transitional morphology in the evolution of avian flight

Barb geometry of asymmetrical feathers reveals a transitional morphology in the evolution of avian flight

FANTASY VS REALITY: A Critique of Smith et al.'s Bird Origins

Rhetoric vs. reality: A commentary on “Bird Origins Anew” by A. Feduccia

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