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largely cursorial adaptations whereas the arms had been elongated in order to climb. Feathers, originally serving the insulation of an already warm-blooded animal, would by elongation have turned the arms into wings in order to fly. More generally, the proavians would, in view of their basal theropod forebears and bird descendants, have been typified by long necks, a short trunk, long fingers with opposable digits, a decoupling of the
207:, both adherents of the "thecodont" hypothesis about the origins of birds. These "proaves" were supposed to be arboreal, with short necks, long trunks, sprawling legs, non-elongated hindlimbs, small hands and feet, small general size, and gliding on membranes. Feduccia's "protoavis" had membranes on the forelimbs only and was fashioned on the model of
99:
six years before, in 1900, in an article dealing with the hypothetical common ancestors of dinosaurs and birds. Pycraft assumed that birds had developed as tree-dwelling dinosaurs, gliding on membranes between the limbs and the trunk. These membranes would gradually have been covered by increasingly
243:
tried to conceptually model a "pro-avian". In his view the direct ancestors of birds cannot have been completely arboreal, because in that case they would probably have used membranes to fly. He thought they must have represented an intermediate ecological stage, in which the hindlimbs still had
192:, breathing new life into the hypothesis that birds were dinosaurs, revived the interest in the direct ancestors of birds. Ostrom assumed these were cursorial. An illustration of a running dinosaur explicitly indicated as a "Proavis" was in 1976 published by
131:
origin, not arboreal. The "Pro-Avis" would thus have been a running animal, accelerating and prolonging its jumps by flapping with feathered forelimbs. There is a model of Nopcsa's restoration, still preserved, and recently restored, in the
284:
300:
224:
proposed their "pouncing proavis model", an hypothesis entailing that the origin of avian flight rested in a predatory behaviour, the "proavis" jumping on its prey from trees (see
91:. Pycraft added to his article his own drawn depiction of the hypothetical animal, a restoration entitled "One of the Pro-Aves". Pycraft's "Pro-Avis" (singular of "Pro-Aves") was
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50:
and was coined in the early 20th century in an attempt to support and explain the hypothetical evolutionary steps and anatomical adaptations leading from non-avian
351:
221:
245:
117:, who, while residing at London, had seen Pycraft's restoration, drew his own vision of the animal, a picture and article published in a 1907 issue of the
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581:
Garner, J.P., G.K, Taylor, and A.L.R. Thomas, 1999, "On the origins of birds: the sequence of character acquisition in the evolution of avian flight",
200:
316:
162:, this time presenting the public with more accurate and anatomically probable drawings. Heilmann favoured a scientific model in which the assumed
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252:, a shallow tail, and a weight of about one kilogramme. Paul illustrated his analysis with a skeletal diagram, accompanied by a
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Osborn H. F., "Reconsideration of the
Evidence for a Common Dinosaur-Avian Stem in the Permian",
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84:
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43:
8:
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266:, the group consisting of birds and their closest relatives, the Italian paleontologist
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Hypothetical restoration of "one of the Pro-Aves", as shown at the
British Museum by
450:, Vol. XXVII, Published by the Academy, editor: Edmund Otis Hovey, 4 May 1916, p. 31
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181:. The animal illustration, as were all illustrations in the book, was painted by
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In 1991 and 1996 "proavis" or "protoavis" models were proposed by respectively
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635:
599:
Dinosaurs of the Air: The
Evolution and Loss of Flight in Dinosaurs and Birds
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204:
357:
Heilmann's hypothetical illustration of a pair of fighting 'Proaves' (1916).
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The term "Proavis" was first coined, although under the form "Pro-Aves", by
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more elongated scales, which eventually would have evolved into feathers.
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189:
127:). But this time, for his own "Pro-Avis" restoration, Nopcsa suggested a
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62:
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in 1907 after having seen the
Pycraft restoration "One of the Pro-Aves".
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Peters, D.S. & Gutmann, W.F., 1976, "Die
Stellung des „Urvogels“
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17:
554:
Origins of the Higher Groups of
Tetrapods: Controversy and Consensus
505:, original 1910 edition, public domain PDF, biodiversitylibrary.org
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in "The Origin of Birds", a 1906 article published in the magazine
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552:: Quo Vadis?" In: Hans-Peter Schultze and Linda Trueb, editors,
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was used again in 1999, when Joseph Garner, Graham Taylor, and
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was arboreal and of thecodontian descent, thus not a dinosaur.
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was described, at the time the most basal known member of the
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remarked it bore an uncanny resemblance to Paul's "proavis".
136:, the only remaining university zoological museum in London.
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47:
518:(Proavis illustration from 1960, book published in 1961)
491:, as mentioned in the University College London website
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William K. Gregory, "Theories of the Origin of Birds",
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Illustration of "a running Pro-Avis" as envisioned by
459:Nopcsa, F. (1907) "Ideas on the Origin of Flight".
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Nopcsa's illustration on its original publication (
147:(in page 39). In the following years, as of 1913,
123:(an English science publication nowadays known as
61:. The term has also been used by defenders of the
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377:, a hypothetical stage and a modern bird (1922).
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461:Proceedings of the Zoological Society of London
308:Proceedings of the Zoological Society of London
120:Proceedings of the Zoological Society of London
31:in 1906 (here extracted from Pycraft 1910 book
143:, in 1910, he reinserted his 1906 restoration
617:Theropoda: The Most Inclusive Blog containing
322:A hypothetical "Tetrapteryx", as imagined by
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248:of the forelimbs and hindlimbs, a lack of a
615:: nuova luce sull'origine degli uccelli",
572:. 420 pp. New Haven: Yale University Press
448:Annals of the New York Academy of Sciences
601:, Johns Hopkins University Press, 473 pp
22:
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634:
420:Pycraft W. P., "The Origin of Birds",
475:, as mentioned and described in the
103:A year after Pycraft's article, the
279:Some hypothetical early bird stages
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570:The Origin and Evolution of Birds
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139:When Pycraft published his book
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422:Knowledge and Scientific News
256:of a "proavis". When in 2013
188:During the 1970s the work of
89:Knowledge and Scientific News
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44:hypothetical extinct species
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437:, Vol. XXXIV, N° 406. 1900.
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625:accessed 3 November 2013
548:Tarsitano. S.F., 1991, "
46:or hypothetical extinct
16:Not to be confused with
489:Grant Museum of Zoology
435:The American Naturalist
134:Grant Museum of Zoology
394:Origin of avian flight
369:Beebe's comparison of
341:'s arboreal vision of
230:Origin of avian flight
226:pouncing proavis model
36:
623:Saltasaurus loricatus
85:William Plane Pycraft
29:William Plane Pycraft
26:
619:Allosaurus fragilis
568:Feduccia, A., 1996,
408:Notes and references
237:Dinosaurs of the Air
194:Dieter Stefan Peters
400:The Origin of Birds
246:locomotor functions
151:artist and amateur
145:One of the Pro-Aves
642:Evolution of birds
597:Paul, G.S., 2002,
502:A History of Birds
141:A History of Birds
125:Journal of Zoology
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33:A History of Birds
583:The Royal Society
473:Proavis wax model
254:life illustration
235:In his 2002 book
65:origin of birds.
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588:: 1259-1266
371:Tetrapteryx
250:propatagium
190:John Ostrom
78:osteologist
268:Andrea Cau
108:aristocrat
611:Cau, A. "
216:The term
169:In 1961,
153:zoologist
129:cursorial
105:Hungarian
82:zoologist
55:dinosaurs
18:Protoavis
636:Category
479:website.
383:See also
310:, 1907).
259:Aurornis
93:arboreal
52:theropod
621:but not
345:(1916).
343:Proavis
326:(1915).
274:Gallery
264:Avialae
218:Proavis
164:Proavis
160:Proavis
75:English
69:History
40:Proavis
403:(book)
149:Danish
171:Czech
59:birds
48:taxon
213:.
203:and
110:and
80:and
586:266
537:106
232:).
228:in
57:to
638::
561:^
373:,
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185:.
35:).
20:.
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