What follows, is my attempt to integrate the massive amounts of new information in a diagram that reflects current thinking on the phenotypic evolution of feathers. Nevertheless, feathers are also unique in that sequential variability in feather structure is produced from the same follicle. The outgroup includes scutes, claws, and scales, and is based on a larger (14.4 kd) keratin and differ in patterns of production and development. Changes of both types produce patterns of gene expression that result in alterations of growth patterns and, further downstream, morphology. However, it is conceivable that no neornthine feather retains this very primitive morphology. Fig. The visible structure was tubercle-like. Structural redundancy at the level of genes, proteins, and structural elements is inherent. Various display feathers consist of fused barbs or selective elimination of barbs. The interpretation of the nature of a primitive feather has often been related to function. Perhaps the most primitive structure unit was cable-like and reflected the filamented keratin macromolecule. The processes involve the formation of periodic symmetrical structures as the result of induction between germ layers; mechanical events derived from the motion of cells and sheets of cells; periodic boarder or boundary formation within single epithelial layers; and the correlation of histogenetic events (e.g., keratinization) in precise fashion within such boundaries. The Yixian dinosaurs were cursorial, bipedal, and not capable of flight. Moreover, barbs on single feathers can have identical protein composition, but with modified filament arrangements and strikingly different shapes (Brush, 1978). A Kovalev, AE Filippov, SN Gorb (2014) Unzipping bird feathers. The simple fusion of individual proto-barbs would produce a morphology identifiable as natal down. The pennaceous feather is a type of feather present in most modern birds and in some other species of maniraptoriform dinosaurs.. These feathers are usually the stiffest and largest feathers on a bird. The existence of diverse feather morphology even on individuals is quite consistent with a single genetic construction. Alan H. Brush, Evolving a Protofeather and Feather Diversity, American Zoologist, Volume 40, Issue 4, August 2000, Pages 631–639, https://doi.org/10.1093/icb/40.4.631. thicker, softer, denser, and more hair-like. Patterns of differentiation and cellular functions are, in turn, regulated by genes and chemical growth factors that regulate segmentation of the repeated, linear occurrence of simple elements. (ornithology) Any feather possessing a central shaft (rachis), usually with vanes composed of barbs. All the latest wordy news, linguistic insights, offers and competitions every month. Modified entries © 2019 At least two recognizable feather types are found on bird fossils from the early Cretaceous (Carroll, 1997; Padian and Chiappe, 1998). Our new online dictionaries for schools provide a safe and appropriate environment for children. A good example of this can be seen on the penguin where the feathers are so close together and tight on the body that it actually looks like skin rather than the feathers that are actually present. Natal down is the earliest feather (first) generation in ontogeny. As a result, plumulaceous feathers cannot hold anything except a delicate, rounded form. Feathers are not weight-bearing elements, and they are flexible, not jointed. The feathers on Archaeopteryx lithographica are essentially modern in their morphological features (Griffiths, 1996). Contour feather definition, one of the feathers that form the surface plumage of a bird, including those of the wings and tail but excluding such specialized types as downs and filoplumes. one of the feathers that form the surface, Most material © 2005, 1997, 1991 by Penguin Random House LLC. More than a single feather type exists in both the chronologically younger Chinese specimens and in the more advanced, but older, Archaeopteryx. By comparison, the most primitive animals to possess feathers are the maniraptorian dinosaurs, Protarchaeopteryx and Caudipteryx (Ji et al., 1998). It had an hollow internal portion with the medulla occupied by fluid with blood and nerve supply. These numerous feathers are typically open structures that underlie body contour feathers and originate in the contour feather follicle. An event such as the appearance of feathers must involve a hierarchical array of events and changes. The individual growth centers were structured internally and functioned like the extant barb ridge. When coupled with pigment patterns, the visual effect of these feathers can be stunning. of many birds are long, thin feathers called filoplumes, as well as powder feathers. See more. Structural elements are produced in transformed cells within the follicle. These structures are bristle-like, grow continually, and have an extraordinary papillary organization. Rather, if individual placodes gave rise to multiple barb ridges that fused proximally, a structure resembling natal down would have resulted. Although follicles in different locations on the body produce different feathers, they are all the result of uniform processing within the module. However, rather than being derived directly from a flat Archosaurian scale (Maderson, 1972), a tubercle-like morphology was involved. While all feathers wear, they are replaced regularly by the molt processes. Their barbs usually lack hooks, so their vanes are not pennaceous. Feathers grow out of and remain attached to a feather follicle in the epidermis. Interest in the origin of feathers was renewed recently with the discovery in China of Sinosauropteryx prima (Ji and Ji, 1996, original in Chinese). ‘The nights are fair drawing in’ is a trope about the weather that applies powerfully as you read this. By implication, once a primitive feather emerged, the subsequent morphological evolution could have been implemented by the selective stabilization of particular forms within the ontogenetic repertory. The online version of the Collins Dictionary has just been updated again, with another batch of new words and meanings inspired by the events of the summer. The essential design of feathers must have been constrained by geometric rules, the properties of the constructional materials, and the process of growth and development (for a recent general discussion, see Authur, 1997). I applaud their organizational and editorial skills. Morphology is relatively simple. Examples include the crown and tail feathers of birds-of-paradise, drongos, Bristle-thigh Curlew (Numenius tahitiensis), etc. I submit that the default structure was likely a protofeather (in this case a simple filament) or a simple natal down. by Penguin Random House LLC and HarperCollins Publishers Ltd. Radio astronomy is a branch of science in which radio telescopes are used to receive and analyse radio waves from space. Smith, P. E., N. M. Everson, D. York, M. Chang, F. Jin, J. Li, S. Cumbaa, and D. Russell. What seems to be lacking is an attempt to establish polarity in the feather phenotypes. Contour feathers are abundant and typically consist of both plumulose and pennaceous portions. From the Symposium Evolutionary Origin of Feathers presented at the Annual Meeting of the Society for Integrative and Comparative Biology, 6–10 January 1999, at Denver, Colorado. Their barbs have rami that are less stiff and the barbules are usually either reduced or thinner. Once the minimal structural element, presumably recognizable as a barb, existed, a variety of phenotypes followed rapidly. Node 3: includes pennaceous and plumulose barbs; rachis central structure, shaft often curved on long axis; full array of barbule morphology; barbs reduced or absent in selected areas. This category includes feathers that exist in various combinations of structural elements. They come from many sources and are not checked. In essence only one degree of branching is present. Although probably younger than Archaeopteryx, these finds establish the presence of feathers in an avian ancestor and demonstrate that their origin was followed quickly or accompanied by the potential for great phenotypic plasticity. Subsequent differentiation is controlled by the follicular symmetry, and the feather shape is regulated by barb length. The downs themselves are quite variable in shape. Chemically the keratin of these structure differs consistently in the presence in the presence of a repeated tripeptide. These processes together integrate the structural elements and reflect adaptations to environmental conditions.