Identification of a unique barb from the dorsal body contour feathers of the Indian Pitta Pitta brachyura (Aves: Passeriformes: Pittidae)

Earlier research on feather morphology emphasized comprehensively on the body contour feather than various other types of feathers. Therefore, we conducted a systematic study on all feather types of the Indian Pitta Pitta brachyura, a passerine bird native to the Indian subcontinent. Feather barbs from wing contour, tail contour, body contour, semiplume, down, powder down, and bristle feathers were retrieved from the bird and observed under a light microscope. Primary flight feathers from the right and left wing were longest (85.17 mm and 87.32 mm, respectively), whereas bristle feathers were the shortest (5.31 mm). The mean barb length was observed to be the highest (11.37±0.47 mm) in the wing feather followed by body contour (8.31±0.39 mm), semiplume (8.27±0.22 mm), tail feather (7.85±0.50 mm), down (6.45±0.21 mm), powder down (6.04±0.23 mm), and bristle (2.70±0.07 mm). Pearson correlation was found positive for barb length and feather length of down feathers (r= 0.996, p ≤0.05). We observed a novel type of barb the first time from dorsal body contour feather having plumulaceous barbules at the base followed by pennaceous barbules. This unique barbule arrangement is termed ‘sub-plumulaceous’ as it is distinct and analogous to known ‘sub-pennaceous’ type arrangement found absent in passerines.

Identification of a unique barb from the dorsal body contour feathers of the Indian Pitta Pitta brachyura (Aves: Passeriformes: Pittidae)

Earlier research on feather morphology emphasized comprehensively on the body contour feather than various other types of feathers. Therefore, we conducted a systematic study on all feather types of the Indian Pitta Pitta brachyura, a passerine bird native to the Indian subcontinent. Feather barbs from wing contour, tail contour, body contour, semiplume, down, powder down, and bristle feathers were retrieved from the bird and observed under a light microscope. Primary flight feathers from the right and left wing were longest (85.17 mm and 87.32 mm, respectively), whereas bristle feathers were the shortest (5.31 mm). The mean barb length was observed to be the highest (11.37±0.47 mm) in the wing feather followed by body contour (8.31±0.39 mm), semiplume (8.27±0.22 mm), tail feather (7.85±0.50 mm), down (6.45±0.21 mm), powder down (6.04±0.23 mm), and bristle (2.70±0.07 mm). Pearson correlation was found positive for barb length and feather length of down feathers (r= 0.996, p ≤0.05). We observed a novel type of barb the first time from dorsal body contour feather having plumulaceous barbules at the base followed by pennaceous barbules. This unique barbule arrangement is termed ‘sub-plumulaceous’ as it is distinct and analogous to known ‘sub-pennaceous’ type arrangement found absent in passerines.

Hidden keys to survival: the type, density, pattern and functional role of emperor penguin body feathers

Antarctic penguins survive some of the harshest conditions on the planet. Emperor penguins breed on the sea ice where temperatures drop below −40°C and forage in −1.8°C waters. Their ability to maintain 38°C body temperature in these conditions is due in large part to their feathered coat. Penguins have been reported to have the highest contour feather density of any bird, and both filoplumes and plumules (downy feathers) are reported absent in penguins. In studies modelling the heat transfer properties and the potential biomimetic applications of penguin plumage design, the insulative properties of penguin plumage have been attributed to the single afterfeather attached to contour feathers. This attribution of the afterfeather as the sole insulation component has been repeated in subsequent studies. Our results demonstrate the presence of both plumules and filoplumes in the penguin body plumage. The downy plumules are four times denser than afterfeathers and play a key, previously overlooked role in penguin survival. Our study also does not support the report that emperor penguins have the highest contour feather density.

Die nachweisbaren Strukturen der Federn von Archaeopteryx mit Anmerkungen zu Longisquama und diversen Proavis-Modellen

Die Abstammung der Vögel, die Entwicklung des Vogelfluges und die Evolution der Vogelfeder sind die zentralen Themen, die sehr kontrovers diskutiert werden und bei denen <i>Archaeopteryx</i> als Taxon oder als Modell für die evolutiven Prozesse eine wesentliche Bedeutung zukommt. Dass der erste Fund von <i>Archaeopteryx</i> eine echte Vogelfeder ist und die Abdrücke bei den Skelettfunden von echten Federn stammen, ist offensichtlich. Sie haben einen Schaft, eine Innen- und eine Außenfahne, gebildet von Federästen und Federstrahlen. Der Beschreibung der Konturfeder rezenter flugfähiger Vögel folgt die Beschreibung der Konturfeder von <i>Archaeopteryx</i>. Am Berliner Exemplar lässt sich nachweisen, dass die Fahnen der <i>Archaeopteryx</i>-Federn wie bei den rezenten flugfähigen Vögeln von Bogen- und Hakenstrahlen gebildet werden. <br><br> Schließlich wird auf die gegenwärtige Diskussion von <i>Longisquama</i> hinsichtlich der Evolution der Federn und der Abstammung der Vögel sowie auf geeignete <i>Proavis</i>-Modelle eingegangen. <i>Archaeopteryx</i> hatte bereits hochentwickelte Federn. Wenn die Hautderivate von <i>Longisquama</i> als nonavian feathers den Vogelfedern homolog sind, dann sind sie ein Beleg dafür, dass die Federn in der mittleren Trias entstanden sind. Ihre Flugtauglichkeit erhielten sie erst durch Funktionswechsel. Quadrupede Gleiter eignen sich nicht als <i>Proavis</i>-Modelle. <br><br> The evident structures of the feathers of <i>Archaeopteryx</i> with a statement about <i>Longisquama</i> and diverse models of Proavis. <br><br> The origin of birds, the beginning of the flight of birds and the evolution of feathers are the central themes, which are controversially discussed, separate as well as together. Because of this, <i>Archaeopteryx</i> is of fundamental importance as taxon and as a model for evolutionary processes. That the first fossil finding of <i>Archaeopteryx</i> is a genuine bird feather and the moulds near the skeleton came from genuine feathers is evident. They have a shaft (rachis), an inner and an outer vane, which are formed by barbs and barbules. The existence of distal and proximal barbules has been provided. It was necessary to test, whether proof of that could be furnished on the feather moulds. <br><br> The description of the contour feather of <i>Archaeopteryx</i> follows the description of the contour feather of modern birds, which are able to fly. On the specimen of <i>Archaeopteryx</i> deposited at the Museum für Naturkunde (Berlin) can be shown that the vanes of the feathers are formed by anchoring of distal and proximal barbules, of hook and bow barbules. Additionally, a discussion of <i>Longisquama</i> concerning the evolution of feathers, the origin of birds and the suitable model of <i>Proavis</i> are considered. If derivates of <i>Longisquama</i> as nonavian feathers were homologous to bird feathers, they are an evidence for origin of the feathers in the Middle Triassic. They got their airworthy usefulness by change of function. Quadrupede gliders are unsuitable as <i>Proavis</i> models. <br><br> doi:<a href="http://dx.doi.org/10.1002/mmng.20030060111" target="_blank">10.1002/mmng.20030060111</a>