Only rarely are green plumage colors due to the presence of green pigments. The best known is turacoverdin. Two galliform species (Ithaginis, Rollolus), Jacana and some anseriform species (Somateria, Nettapus) also have green pigments. The reflectance spectra of plumage pigmented by turacoverdin are characterized by distinct minima at about 570 and 610 nm. These minima represent absorption bands as confirmed by a transmittance spectrum of a turacoverdin extract. Surprisingly, the spectra of the two galliform species and Jacana also exhibit the characteristics of the turacoverdin spectrum, while that of Somateria is different. I show that the pigments of Ithaginis, Rollolus, and Jacana also resemble turacoverdin in containing copper in relatively high concentration, and conclude that these pigments are identical with or closely related to turacoverdin. Intra- and interspecific variation in reflectance spectra is assumed to be largely determined by the presence of dark, nongreen pigments in the plumage. The spectrum of turacoverdin supports the hypothesis that the pigment is closely related to the well-known red pigment of turacos (Musophagidae)--turacin. However, the chemical constitution of turacoverdin remains unknown. The presence of turacoverdin and turacin in the plumage of the Musophagidae hitherto has been considered an autapomorphy of the turacos. The fact the turacoverdin also is present in two possibly related galliform taxa argues for phylogenetic relationships between the Musophagidae and the Galliformes. Received 3 April 1991, accepted 10 January 1992.

Institute of Population Biology, University of Copenhagen, 2100 Copenhagen f, Denmark GREEN, noniridescent plumage colors can be produced in a number of ways (Auber 1957). The combination of a structural blue color with yellow pigments, as found in parrots, is best known (Frank 1939, Dyck 1971). The olive-green colors obtained by the juxtaposition of yellow and blackish pigments (apposition colors; Au- ber 1957, Dyck 1978) also are widespread. Cen- tral to my two studies is the question of the evolution of plumage colors that resemble the green colors of leaves, without chlorophyll be- ing available as a feather pigment (Needham 1974:81). In principle, the simplest way to pro- duce a green plumage color is to deposit a green pigment within the feather keratin. This pos- sibility has been realized in only a limited num- ber of cases. The best-known green feather pigment is tu- racoverdin. This is found in some turacos (Mu- sophagidae), especially the species of Tauraco and Musophaga, and possibly also in the Great Blue Turaco (Corythaeola cristata; Krukenberg 1882, Moreau 1958). Preliminary chemical stud- ies have been carried out (Moreau 1958). Other known green pigments are zooprasinin in the remiges of the Jacana (Jacana spinosa, Jacanidae; Rensch 1925), phasianoverdin in belly feathers of the Blood Pheasant (Ithaginis cruentus, Pha- sianidae; Gtz 1925), and a green pigment in much of the plumage of the Roulroul (Crested Wood-Partridge, Rollolus roulroul, Phasianidae), especially the female (Vlker 1961). The green pigments in some anseriform species (Nettapus, Somateria; Auber 1957) are poorly known (Brush 1978). I describe the reflectance spectra of green plumage areas in several species and discuss factors that influence the shapes of the spectra. ! compare the reflectance spectra with the spec- trum of turacoverdin in extract and from this infer the probable identity of some of the pig- ments. MATERIALS AND METHODS Most measurements were performed on study skins from the Zoological Museum, University of Copen- hagen, and the British Museum (Natural History). A few measurements were also carried out on mounted specimens. The spectrum of the nape of an adult male Eider (Sornateria rnollissirna) was scanned on feathers taken from a newly dead bird. Feathers plucked from live birds were obtained from the Zoological Garden, Copenhagen, and kept four months in the dark before measurement. Reflectance spectra were obtained on a Beckman DK-2A spectrophotometer with a reflectance attach- ment and using a reference of magnesium oxide. The illuminated spot was approximately 8 x 8 mm. An extract of turacoverdin was obtained as follows: Green feathers plucked from a 46-year-old study skin of Tauraco schalowi livingstoni were cleaned by ultra- sonic treatment and dried. The green parts of the barbs were cut off and 0.10 g of these placed in 6 ml of 0.8 M aqueous ammonia at room temperature in  the dark for one week. Likewise, extracts were pre- pared of the grey-brown proximal parts of the feath- ers from which the green barbs had been removed,  of grey-brown feathers of Gallinula chloropus, and of  white belly feathers of Larus ridibundus. It was nec- ec essary to add 1:5,000 of commercial sulfonate-free de-  tergent to the latter feathers during the extraction in order to wet the feathers. Absorption spectra were obtained on a Beckman Acta C III spectrophotometer. The copper determinations by flame atomic ab- 0 sorption (Perkin-Elmer) were done on extracts of pig- ments in 0.8-M ammonia. From 2 to 12 mg of feather material were extracted with I ml of solvent at room temperature for about one month. Only green feather parts were used; in Rollolus the melanized barbules were scraped off. RESULTS The reflectance of the green Tauraco breast rises from a minimum at 412 nm to a maximum at 530 nm (Tc in Fig. 1, Table 1), only to fall to two minima at 568 and 612 nm (Figs. 1 and 2, Table 1) and rise again rather steeply to 700 nm. Overall, the reflectance spectra of Corythaeola, Jacana and Ithaginis show higher reflectances than the spectrum of Tauraco, but with similar shapes (Cc, Is, Ic, Figs. 1 and 2). The minima occur at similar wavelengths (Fig. 2, Table 1). Some of the spectra did not show all three min- ima (Table 1), but in these cases an incurvation always was observed on the spectrum in the relevant wavelength region. The shape of the Rollolus reflectance spectrum is similar to that of Tauraco with overall lower reflectance (Rr, Fig. 1). The positions, however, of the three minima are more variable (Table 1), with a less-distinct middle, minimum seen Wavelength (nm) Fig. 1. Reflectance spectra of green-pigmented plumage areas for six species: Rr, Rollolus roulroul; Tc, Tauraco corythaix; Cc, Corythaeola cristata; Ic, Ithaginis cruentus; Sm, Somateria mollissima; and [s, [acana spinosa. only as an incurvation on four of the five spec- tra. The spectra of Rollolus differ from those of Tauraco in the presence of an incurvation at 490 to 495 nm. Also, the maximum in the green is more marked, and three of the five spectra have a weak minimum at 535 nm (not shown). Contrary to results for the above-mentioned species, the Somateria spectrum shows little re- semblance to the Tauraco spectrum. The three minima are lacking. Instead, there is a wide, indistinct minimum at 580 to 590 nm and a faint incurvation at 415-420 nm (Sm, Fig. 1). Figures 3 and 4 illustrate the influence of age and light exposure on the spectrum of Tauraco. The study skin and mounted specimen both were 139 years old at the time of measurement. TABLE 1. Reflectance minima of green-pigmented plumage areas. Species (n) Reflectance minima (nm) a Tauraco corythaix (10) 412 (411-419) 570 (567-575) 612 (611-613) Corythaeola cristata (belly, 4) 414 (412-416, n = 3) 564 (562-564, n = 3) 610 (609-611) Ithaginis cruentus (3) 411 (409-411) 561 (559-563, n = 2) 606 (605-606, n = 2) Rollolus roulroul (5) 416 (404-438) 574 (n = 1) 626 (607-628) Jacana spinosa (4) 411 (407-415) 566 (565-566, n = 2) 606 (604-612) ' Median value and range (in parentheses) for each of three minima. Each specimen represented by one spectrum. Where given minimum not observed on all spectra, the number of spectra on which it was present is indicated. Positions of minima determined with accuracy of + 1-2 nm. - cc r- Js Tc Rr I I [ , 560 580 600 Wevelength (nm) Fig. 2. Detailed reflectance spectra in region 560- 615 nm. Measurements of same specimens as used in Figure 1, but not on exactly same plumage spot. Spec- tra displaced arbitrarily along reflectance axis. Ordi- nate unit is similar for spectra, but not exactly so. Species abbreviations as in Figure 1. The former probably had been kept in darkness for the entire period. The latter is likely to have been on exhibition, exposed to light, up to 120 years. The minimum at 610 nm of the spec- trum of fresh feathers is more pronounced than on the spectra of the old specimens. The dif- Sk 20 / ;  o 70' Wavelength (nm) Fig. 3. Reflectance spectra of green-pgmented plumage of Tauraco corythaix: Fr, sample of fresh feath- ers; Sk, study skin; Mn, mounted specimen. ference is both relative, to the minimum at 565 to 570 nm, and absolute, with the result that the maximum in the green part of the spectrum occurs at shorter wavelengths than in the old specimens. Figures 3 and 4 further indicate that the spectrum of the mounted specimen (ex- posed to light) differs more from the spectrum of the fresh feathers than from that of the study skin. In Jacana, marked differences between the A B o 560 580 600 Wavelength (nm) Fig. 4. (A) Detailed reflectance spectra in region 560-615 nm. Measurements of same specimens as used in Figure 3, with only spectrum Fr on exactly same plumage spot. Abbreviations as in Figure 3. (B) Detail of transmittance spectrum 1 (Fig. 5). Ordinate unit chosen so that 3% transmittance = 1% reflectance. 80 20 ' ' / / ,' / / 400 500 600 700 Wavelength (nm) Fig. 5. Transmittance spectra: (1) freshly prepared extract of Taura1/2o turacoverdin; (2) same extract two months later; (3) extract of pigment from grey-brown Tauraco feathers. reflectance spectra of fresh feathers, study skins, and a mounted specimen were not detected. The transmittance of an extract of turacov- erdin prepared from Tauraco (with 21% solvent added before measurement) rises from a low plateau at 400 to 440 nm to a maximum at 504 nm, fails to two minima at 565 and 597.5 nm (with an additional minimum indicated at 530 nm), and rises again rather steeply up to 700 nm (Figs. 4 and 5). After storage at 4øC for two months, the ab- sorption of the extract increased markedly (Fig. 5). Also, the positions of the two minima shifted slightly (to 566 and 600 nm), and there was then a minimum in the short-wave region of uncer- tain position due to the high absorption. The diluted extract (1:3) had this minimum at 404 nm, and the other two at 564 and 597 nm. The transmittance of grey-brown Tauraco feathers increased smoothly with wavelength, except for weak incurvations at 415 and z600 nm (Fig. 5). The transmittance spectrum of grey-brown Gallinula feathers strongly re- sembles this spectrum, but lacks the incurva- tions, which makes it probable that these orig- inate from contamination with green feather parts in the sample of grey-brown Tauraco feath- ers. The extract from white Larus feathers had an absorption close to zero. The transmittance spectra of extracts in dilute aqueous ammonia of the pigments of Corythaeo- la, Ithaginis, [acana, and Rollolus show, in gen- eral, the characteristics of the Tauraco spectrum. However, the minima in the 550 to 600 nm region were faint and the spectra somewhat variable. This was due to having too little feath- er material available and melanized feather parts that were not removed prior to extraction. The copper concentrations of feathers show- ing Tauraco-like spectra are relatively high (Ta- ble 2). Dark and white reference feathers have low concentrations, close to the detection limit. DISCUSSION The reflectance spectra of plumage areas col- ored by green pigments differ markedly from both the spectra of a green parrot or an olive- green passerine (Fig. 6). The Somateria spec- trum differs in the very gradual increase from 400 nm up to the maximum in the green region, while the other spectra display a strong mini- TABLE 2. Copper concentrations (g/mg) in green feather parts and in reference feathers. Species Cu concentration Tauraco schalowi 1.2 Corythaeola (belly) 0.3 Corythaeola (tail) 0.2 Ithaginis 0.5 Rollolus 0.4 Jacana 0.2 Reference feathers Tauraco (tail, dark) -< 0.03 Fulica (black) -< 0.03 Larus (white) -< 0.03 10 Tp -exp 9 8 86  3 2 1 400 450 5 0 550 600 650 700 Wavelength (nm) Fig. 6. Reflectance spectra: Th, green back of Trichoglossus haematodus; Si, olive-green back of Satrapa icter- ophrys; Tp-fr, fresh grey-brown back feathers of Turdus philomelos; and Tp-exp, same feathers after 13 months exposure to light. mum at 410 to 420 nm and two weaker ones at 570 and 610 nm. Also, the green-pigment spectra do not resemble the spectra of other types of green plumage areas where green pig- ments are not involved (Dyck 1966, 1987, and unpublished spectra). The implication is that the characteristics of the spectra are largely due to the green pigments present. Identity of pigments.--Turacoverdin is soluble in weak base (Krukenberg 1882) as is turacin (Church 1870). The absorption bands of the tu- racoverdin extract (Figs. 4 and 5) match the re- flectance minima of the corresponding reflec- tance spectrum (Figs. 1 and 4) both with respect to the relative intensity and the position on the wavelength scale. The exact wavelengths at which the bands occur are somewhat shorter in extract as compared to pigment in situ. This phe- nomenon is general for pigments (Bellin 1965) and has been reported also for other feather pigments (Dyck 1966, V61ker 1942), including turacin (Keilin 1926). Therefore, I conclude that the shape of the reflectance spectrum of Tauraco is determined primarily by the light-absorption profile of turacoverdin. Since the reflectance spectra of Corythaeola, Ithaginis, and Jacana show the distinctive fea- tures of the Tauraco spectrum, this strongly in- dicates that their pigments are identical with or similar to turacoverdin. The Rollolus spectrum shows most of the characteristics of the Tauraco spectrum, with additional features as well. V61ker (1961) reported, in a preliminary inves- tigation of the Rollolus pigment, that the feath- ers also contain small amounts of yellow carot- enoids, mainly lutein. Feathers with lutein as the dominant pigment show a marked reflec- tance minimum at 490 nm (unpubl. data on Oriolus oriolus; cf. V61ker 1960). The weak re- flectance minimum at 490 to 495 nm of the Rol- lolus plumage, therefore, may be due to lutein. The weak reflectance minimum at 535 nm on some Rollolus spectra may correspond to the weak minimum at 530 nm on the turacover- din transmittance spectrum. V61ker (1961) re- marked on the similarity in hue between the pigment of Rollolus and turacoverdin, but found that they differed in solubility in alkaline ex- tracts and in their reactions with concentrated sulphuric acid (without specifying the differ- ences). He did not state whether he considered the pigments chemically related. The pigments of Corythaeola, Ithaginis, Rollo- lus, and Jacana further agree with turacoverdin in being readily soluble in weak aqueous base and in containing copper in relatively high con- centration. The value obtained here for T. scha- lowi is very similar to that obtained by Shaw and Bather (in Moreau 1958) for T. corythaix-- 0.8 g Cu/mg feather. Brunet et al. (in Moreau 1958) reported that turacoverdin "appears to consist of two pig- ments, one less soluble than the other." They gave no further details. Based on the above findings, I conclude that the pigments of Corythaeola, Ithaginis, Rollolus, and Jacana are closely related, if not identical to turacoverdin of Tauraco. This conclusion is not changed materially if turacoverdin is a mix- ture of pigments. Thus, earlier statements that the pigments of Ithaginis, Rollolus, and Jacana are carotenoids (G6tz 1925, Rensch 1925, Auber 1957) are probably erroneous. As shown by its spectrum, the Somateria pig- ment is probably unrelated to turacoverdin. Brush (1978) found its spectrum to be like other xanthophylls. J. Hudon (pers. comm.), from characteristics such as spectrum and shape of crystals, suggested the Somateria pigment to be a porphyrin, but one of unusual nature. The inter- and intraspecific differences among the reflectance spectra of Tauraco, Corythaeola, Ithaginis, Rollolus, and Jacana can be attributed to a number of factors. These are addressed brief- ly below. Variation in overall level of reflectance.--In Tau- raco, the green pigment is deposited in the rami. The barbules are reduced terminally and grey- brown basally. These grey-brown barbules are in part visible between the green rami. In Rol- lolus, the green pigment likewise is found in the rami. The lower reflectance is due to the black-pigmented barbules. In the remiges of Ja- cana, a species with relatively high reflectance values, the green pigment is present in both barbules and rami with a high pigment con- centration in the distal barbules. There is very little, if any, dark pigment in these feather parts. The feather vane also is continuous, and there are no clefts through which light can pass and be absorbed underneath. Altogether, these facts explain the overall high reflectance of the Ja- cana spectrum. All things considered, it appears that the overall level of reflectance is determined pri- marily by the presence of dark, nongreen pig- ments in the visible portion of the plumage. Intraspecific variation in shape of spectra.--Vari- ation in the shape of spectra obtained from a series of study skins of T. corythaix is slight. The variation recorded probably is mainly attrib- utable to the degree of visibility of the grey- brown barbules in the measured plumage area. Variation among spectra of feathers differing in age and previous exposure to light (Figs. 3 and 4) is more marked. However, age and ex- posure to light were not solely responsible for the differences between the spectrum of fresh feathers and the two other spectra. The sample of fresh feathers was prepared so that the ter- minal parts of the green rami with the grey- brown barbules reduced dominated in its cen- ter. Thus, the color of the barbules contributed considerably less to the overall reflectance than in the intact plumage. This factor undoubtedly explains why the reflectance spectrum of fresh feathers matches the transmittance spectrum more closely than do the other reflectance spec- tra (Fig. 4). Additional factors may explain the differ- ences between the three spectra. (1) One pos- sible factor is a change in the reflectance prop- erties of the melanized feather parts with time and exposure to light. Figure 6 shows the re- flectance spectrum of a sample of grey-brown back feathers of Turdus philomelos when fresh and after 13 months of exposure to daylight filtered through a window glass. Reflectance increases and so does the inclination of the spectrum. If it is assumed that the reflectance properties of melanized feather parts of Tauraco respond similarly, then a change in the shape of spectrum in the sequence "fresh to study skin to mounted specimen" (Figs. 3 and 4) is to be expected. The fact that the mounted specimen shows slightly lower reflectance than the study skin does not fit, however. (2) A second possi- bility is a change of light absorption by tura- coverdin with time and exposure to light. The changes observed with the pigment extract (Fig. 5) point to this as a possible cause. (3) Third, a change of the keratin with time and exposure to light may cause a change in the shapes of the spectra, because this may affect binding of the pigment to keratin. Such binding affects the absorption spectrum of the pigments (Bellin 1965). Of these three factors I consider the first to be the most important. This is supported by the fact that Jacana, which has little or no dark pig- ment in the green-plumage area, showed no marked differences between reflectance spectra of fresh feathers, study skins, and a mounted specimen. Interspecific variation in shape of spectra.--Vari- ation among Corythaeola, Ithaginis, and Jacana is related to one or several factors. (1) First, it could be due to a variable contribution of feather parts pigmented green to the overall reflectance of the measured spot; this, in turn, would depend on the concentration of green pigment and the area of the green-pigmented feather parts rel- ative to the total area of the plumage spot. The spectra indicate that this contribution is largest in Jacana and smallest in Corythaeola. (2) Second, there could be variation in the chemical com- position and concentration of the dark (grey- brown to blackish) pigments. (3) Third, varia- tion may be present in the degree of reflection from the feather medulla and the spectral char- acteristics of the light reflected from the me- dulla. These characteristics are known to vary among species (Dyck 1978). In Ithaginis, the re- flection of green light from the barbules is in- creased by the presence of air in the barbule cells (Schmidt 1961), which is exceptional as barbule cells are normally solid. (4) Fourth, there could be variation in the chemical composition of the green pigment(s). Of these four factors, I consider (1) and (2) the most important. This is supported by the fact that interspecific variation in the shapes of the spectra resembles to a considerable extent the observed intraspecific variation. Relationship between turacoverdin and turacin.-- In Church's (1870, 1892) studies of the red feath- er pigment of touracos (turacin; copper-uro- porphyrin III), he found that, when exposed to air and moisture or for extended periods of time to continued ebullition with water or alkaline liquids, turacin acquired a color closely resem- bling that of chlorophyll. He considered it like- ly that this alteration product of turacin was identical to turacoverdin. This possibility has been mentioned by more recent authors as well (Keilin and McCosker 1961, Brush 1978). Table 3 compares the positions of the absorp- tion bands of this "altered turacin" with those of turacoverdin, Ithaginis pigment, and turacin. Clearly, there is agreement between "altered turacin" and turacoverdin (and Ithaginis pig- ment). The table also shows that the a- and E-bands of turacin are retained in the alteration product as noted by Church (1870, 1892), and are present in turacoverdin. Keilin and McCosker (1961) oxidized turacin and produced copper-uroporphyrin I in vitro with H202 formed during the copper-catalyzed oxidation of ascorbate. In both cases, a green pigment resulted with absorption bands cor- responding to those of altered turacin (Table 3). However, the ,-band was not the strongest as in turacoverdin (Fig. 5). Church (1892) re- marked that the ,-band of altered turacin is very distinctive, but always accompanied by the E- and 6-bands. The spectral data support the suggestion that turacoverdin is identical to or closely related to an oxidized form of turacin. Several additional facts suggest that turacin and turacoverdin are closely related: (1) In breast patches and crests of some species the two pigments intermingle within individual feathers (Moreau 1958). (2) Turacin, which has a much more limited dis- tribution than turacoverdin, occurs only in the presence of the latter (Moreau 1958). (3) Both pigments contain copper. (4) The two pigments show similar appearances and deposition pat- terns in the feather cells under the transmission electron microscope (turacin, Schmidt and Rus- ka 1963; turacoverdin, my unpubl. observ.). However, the exact nature of this relationship still remains to be elucidated a century after the pioneer studies by Church (1870, 1892) and Kru- kenberg (1882). Systematics.--The finding that the green pig- ment of Corythaeola is turacoverdin fits well with the widespread occurrence of the pigment within the Musophagidae. Brush and Witt (1983) found Corythaeola to be closely related to Crinifer and Gallirex. Both possess turacoverdin, al- though the former only has small amounts (Au- ber 1957). Moreau (1958) expressed doubt about the pigment in Corythaeola, because the plum- age looks yellower than that of Tauraco spp. The more yellowish appearance can be attributed to an overall higher reflectance (Fig. 1; see Dyck 1966:65). Ithaginis and Rollolus both belong to the Per- dicinae (Smythies 1953, Stresemann and Stre- seroann 1966). Ithaginis, despite its English com- mon name of Blood Pheasant, exhibits the adult tail-molt pattern characteristic of the Perdicinae (Stresemann and Stresemann 1966). Both spe- cies differ from the majority of perdicine species in showing marked sexual dimorphism in plumage color. Both species are found in South- east Asia, but their ranges do not overlap and their habitats are very different. Their ranges are relatively close in Burma, where Ithaginis occurs at high altitudes in mountains in the north, and Rollolus in mature forest in lowland and on hills in the extreme south (Smythies 1953, Medway and Wells 1976). Taking these facts into consideration, I find it likely that the presence of turacoverdin in- TABLE 3. Absorption bands of extracts of green feather pigments, turacin and derivatives of turacin. Absorption band (nm) a Pigment (solvent)   c 7 Reference Turacoverdin (2% Na2CO) + Krukenberg 1882 Turacoverdin (0.8 M NH3) -- 530 565 597.5 This study Green "altered turacin" (Na2CO3) 473-494 523 562 597 Church 1870, 1892 Oxidized copper-uroporphyrin I (phosphate buffer, pH = 6.4) 484 526 562 610 Keilin and McCosker 1961 Oxidized turacin (phosphate buffer, pH = 6.4) 484 526 562 610 Keilin and McCosker 1961 Turacin (faintly ammoniacal, fresh preparation) 475-496 523 562 -- Church 1892 Ithaginis pigment (2% KOH) -- -- 569 593 G6tz 1925 Terminology of Church (1870, 1892). "Scharfes dunkles Absorptionsband unmittelbar vor D [Sharp, dark absorption band very close to D]." dicates a close relationship between the two species. The color patterns, however, are quite different and, therefore, I consider it unlikely that Ithaginis and Rollolus are each other's closest relatives. Instead, I assume that a common an- cestor to a group of galliform species including Ithaginis and Rollolus had turacoverdin. Thus, turacoverdin becomes a symplesiomorphy for this group of species. There seems to be consensus that the Jacan- idae belong to the Charadriiformes/Charadrii (Fry 1983, Sibley et al. 1988). This makes it vir- tually impossible that turacoverdin in Jacana re- flects a common ancestry with either the Mu- sophagidae or a group of galliform species. The pigment must have evolved independently in Jacana. In support of this supposition is the fact that the pigment in Jacana is found in the rem- iges, primarily the barbules. In the musophagid and galliform species, it is found mainly in body feathers and possibly exclusively in rami (Tau- raco, Rollolus), or in rami and barbules (Cory- thaeola [tail], Ithaginis). The phylogenetic relationships of the Mu- sophagidae are still uncertain (van Tuinen and Valentine 1986). In Sibley and Ahlquist's (1972) review, they listed the Galliformes as one of the more realistic possibilities in terms of closest relatives. Since then, several relevant studies have appeared. Some of these (Cerny 1972, van Tuinen and Valentine 1986, Brom 1991) support affinity to members of the Galliformes, while others (Gysels 1969, Sibley and Ahlquist 1972, 1985) do not. The presence of turacoverdin and turacin in the feathers is often mentioned (e.g. Turner and Grimes 1985) as an autapomorphy of the Mu- sophagidae. The fact that turacoverdin is pres- ent also in two galliform species (possibly re- lated) is a further, strong argument for a relatively close phylogenetic relationship be- tween the Musophagidae and the Galliformes. More specifically, the pigment data suggest that turacos evolved from a group of galliform spe- cies that have turacoverdin as a symplesiomor- phy, and are represented by the extant genera Ithaginis and Rollolus. Judged from the appear- ance of the green feathers, Rollolus is closer to a possible ancestor than is Ithaginis. A transition from a bird living on the ground in the jungle, feeding partly on vegetable matter (as Rollolus; Robinson and Chasen 1936), to an arboreal for- est bird almost exclusively vegetarian (as some turacos; Turner and Grimes 1985) is, in princi- ple, easy to imagine. ACKNOWLEDGMENTS The reflectance spectra were obtained at the Danish Defence Research Board, and I thank members of its staff for their assistance. For the loan of skins, I thank the late F. Salomonsen and J. Fjeldst (Copenhagen Zool. Mus.), as well as I. C. J. Galbraith (Brit. Mus. [Nat. Hist.]). The late H. Poulsen kindly supplied me with fresh feathers, and J. Fjeldst with a Tauraco skin for pigment extraction. Poul Prento and Ib Trabjerg helped with the absorption spectrophotometry and Jorgen Larsen with copper determinations. Karen Whitney and Jette Andersen supplied valuable tech- nical assistance, and Beth Beyerholm kindly drafted the figures. I thank an anonymous referee, E. H. Burtt, Jr., and J. Hudon for critical reviews of the manuscript at various stages of its preparation and for help in improving my English. J. Fjeldst helped with a dis- cussion of phylogenetic aspects, and J. Andersen also helped improve the English used in this paper. LITERATURE CITED AUBER, L. 1957. The distribution of structural colours and unusual pigments in the class Aves. Ibis 99: 463-476. BELEIN, J.S. 1965. Properties of pigments in the bound state: A review. Photochem. Photobiol. 4:33-44. BROM, T.G. 1991. Variability and phylogenetic sig- nificance of detachable nodes in feathers of tin- amous, galliforms and turacos. J. Zool. (Lond.) 255:589-604. BRUS, A. 1978. Avian pigmentation. Pages 141-164 in Chemical zoology, vol. 10 (M. Florkin, T. S. Bradley, and A. Brush, Eds.). Academic Press, New York. BRUSh, A. H., D H.-H. 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