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Home , Jacamar, Malacoptila, Notharchus, Piciformes, Pici (taxon), Puffbird

EVIDENCE FOR A POLYPHYLETIC ORIGIN OF THE

STORRS L. OLSON NationalMuseum of Natural History, SmithsonianInstitution, Washington,D.C. 20560 USA

ABSTRACT.--Despitetwo recent anatomical studies to the contrary, the Piciformes appears to be polyphyletic. The structure of the zygodactyl foot in the Galbulae is very distinct from that in the , and no unique sharedderived charactersof the tarsometatarsus have been demonstratedfor thesetwo taxa. The supposedlythree-headed origin of M. flexor hallucis longus sharedby the Galbulae and Pici is doubtfully homologousbetween the two groups, leaving only the Type VI deep flexor tendonsas defining the order Piciformes.This condition is probably a convergentsimilarity. Evidence is presentedsupporting a close relationship between the Galbulae and the suborder Coracii and between the Pici and the Passeriformes.There are fewer characterconflicts with this hypothesisthan with the hy- pothesis that the Piciformes are monophyletic. Problems concerning taxa are also addressed.Received 24 September1981, accepted15 May 1982.

A MONOPHYLETICorigin of the Piciformes with outsidegroups in a manner indicating that appears to have gained support from the si- the zygodactyl condition in ,, multaneous appearance of two cladistic, ana- and Piciformes had arisen independently, tomicalpapers (Swierczewski and Raikow 1981, through convergence. Simpson and Cracraft 1981) that concur in the Although I certainly do not advocate a traditional conceptof the order--a conceptthat monophyleticorigin of zygodactylbirds, the has prevailed at least since the time of Gadow argumentsthat Simpson and Cracraft(1981) and (1893). I depart from this view in considering Swierczewskiand Raikow (1981)present against each of the two major subdivisionsof the Pic- such a hypothesis do not meet the require- iformes, the Galbulae (Bucconidae, Galbuli- ments of their cladisticmethodology. Simpson dae) and the Pici (Capitonidae, Ramphastidae, and Cracraft(1981: 484) concludeonly that "the Indicatoridae, Picidae), to be more closely re- relationships of cuckoos and parrots remain lated to another group than to each other. My among the most enigmaticwithin purpose here is (1) to show that the evidence .... "although "there is a generalacceptance for monophyly is weak, uncorroborated,and among avian systematists. . . that piciforms has in part been misrepresentedby Simpson are most closely related to coraciiformsor to and Cracraft (1981), and (2) to make prelimi- passeriformsand that cuckoosand parrots are nary suggestionsas to the probableclosest rel- not." They concedethat "this hypothesishas atives of the Galbulae and the Pici. yet to be tested cladistically "Swier- czewski and Raikow (1981: 469) state that: "The

THE WEAKNESS OF THE EVIDENCE FOR muscular component of the foot mechanism is PICIFORM MONOPHYLY quite different in [the Cuculidae,Psittacidae, and Piciformes] ... which supports the con- Zygodactyly.--Obligate zygodactyly, the tention (Bock and Miller 1959: 30) that those condition in which the fourth toe is perma- groups became zygodactyl independently." nently reversedand has an enlargedaccessory Both setsof authors have thus tacitly accepted articulatingprocess (the "sehnenhalter"),oc- differences between taxa as evidence of non- curs in cuckoos (Cuculidae, Cuculiformes), relationship,a procedureof which Cracrafthas parrots (Psittacidae,Psittaciformes), and in the been outspokenlycritical (see Olson 1982). Piciformes. This is obviously a derived con- The most complete and original work on the dition in that could be used to define nature of the zygodactyl foot is that of Stein- these taxa as a monophyletic group in a cla- bacher (1935), whose resultshave seldombeen distic sense, unless it were shown that each of accurately represented (a notable exception thesezygodactyl taxa sharesderived characters being Sibley and Ahlquist 1972). Steinbacher

126 The Auk 100: 126-133. January 1983 January1983] PolyphyleticOrigin of thePiciformes 127

A B C D

Fig. 1. Posterior(top row) and lateral (bottom row) views of the distal end of the tarsometatarsusin the four groups of birds with obligate zygodactyly(illustrations from Steinbacher1935). A, ,Centropus ateralbus(Cuculidae, Cuculiformes);B, , Galbularuficauda (Galbulidae, Galbulae, "Piciformes"); C, , Ramphastostoco (Ramphastidae,Pici, Piciformes);D, , Amazonaochrocephala (Psittacidae, Psittaciformes).Abbreviations: Sh = sehnenhalter,C II = trochleafor digit II, C III= trochleafor digit III, C IV = trochleafor digit IV, G IV = articulatingsurface for digit IV, Gsh = articulatingsurface of sehnen- halter, M 16 = depressionfor origin of M. extensorbrevis digiti IV, R = groovefor tendon of M. extensor brevisdigiti IV, M 4 = depressionfor tendonof M. flexorperforatus digiti IV. It canbe seenthat the form of zygodactylyin the Galbulae is completelydifferent from that in the Pici, and the two can in no way be regardedas homologous. The bestinterpretation of the evidencefrom the tarsometatarsusis that zygodactyly evolved independently in all four of these groups. showed that there were four distinct types of viding evidence "that osteological... char- morphologyof the tarsometatarsusin birds with acteristicsof zygodactyly are distinct for the obligatezygodactyly, with that in the Galbulae piciformsand different from cuckoosand par- being as different from that in the Pici as either rots," Simpsonand Cracraft(1981: 484) have of thesetwo is from parrotsor cuckoos(Fig. 1). dearly misrepresentedthe factsand Steinbach- In eachof thesefour groupsthere is a sehnen- er's interpretation of them. halter. Steinbacher (1935: 234) even identified Nowhere do Simpson and Cracraft, nor any a sehnenhalterin owls (Strigiformes),which other authors(e.g. Bockand Miller 1959),show are facultatively zygodactyl. Thus, the state- that there are derived characters of the tarso- ment by Simpsonand Cracraft(1981: 485) that metatarsusthat will distinguish the Galbulae "zygodactyly and the presenceof a sehnen- and Pici from parrotsand cuckoosand that will halter can be interpreted as derived characters establish the Piciformes as a monophyletic definingthe piciforms as monophyletic" is dis- group. In fact, the apparentlyless modified ingenuous.In citing Steinbacher(1935) as pro- trochlea IV and sehnenhalter in the Galbulae 128 $To•s L. O•,soN [Auk, Vol. 100

are actually more similar to the condition in expanded so that fibers also originated from cuckoos,whereas the larger,more discrete,and the proximal end of the fibula and from the distally projecting sehnenhalterin the Pici is median raphe of the adjacentM. flexor perfor- more like that in parrots(Fig. 1). There simply atus digiti III. [Incidentally, Fig. 6d in Simpson is no evidence in the structure of the tarso- and Cracraft (1981) is mislabelled--"Fpp3" metatarsus that will demonstrate a close rela- shouldread "Fp3."] In Trachyphonusthe fibers tionship between the Galbulae and the Pici. originatingon the fibula, and thoseoriginating Swierczewski and Raikow (1981) present six on the raphe of M. flexorperforatus digiti III, myological charactersto define their Clade B are slightly separatedfrom the main belly of (= Galbulae) and six additional myological the musclethat originatesin the popliteal fos- charactersto define their CladeG (= Pici). Thus, sa, thus making the muscle three-headed. these two taxa differ from each other in at least Clearly, M. flexor hallucis longus, in contrib- 12 myological charactersof the hind limb, as uting to the flexion of two toes in addition to well as having a completelydifferent structure the hallux, has become strengthenedby ex- of the tarsometatarsus associated with their re- panding the area of its origin to the two nearest spective forms of zygodactyly. May we not, available structures.This is directly correlated then, apply the same statement that Swier- with the Type VI arrangementof the flexorten- czewski and Raikow used against monophyly donsand is part of the samecharacter complex. of all zygodactylbirds to argue againstmono- I could not detect any separateheads of or- phyly of the Piciformes,namely that "the mus- igin in the bucconid ,however. In- cular componentof the foot systemis quite dif- deed, Swierczewski(1977: 57) statesthat in the ferent in thosegroups," a differencesupporting Galbulidae and Bucconidae the heads are the contentionthat they "becamezygodactyl "somewhatdifficult to separatefrom each oth- independently" (Swierczewski and Raikow er." He alsonotes that the "commonbelly ex- 1981: 469)? tends only about two-thirds the length of the Origin of M. flexor hallucislongus.--Swier- tibiotarsus" in the Galbulae, versus almost the czewski and Raikow state that M. flexor hal- entire lengthof the tibiotarsusin the Pici. Thus, lucis longus has three heads in the Piciformes, it seems far from certain that the nature of the which they interpretas a derivedcondition that origin of this muscle is homologousbetween supports monophyly. Simpson and Cracraft the Galbulae and the Pici or even that it can (1981:483) imply this conditionto be unique really be said to have three heads in the Gal- to the Piciformesby stating that "the muscle bulae. arises by one or two heads in other birds," Type VI flexor tendons.•adow (1893) de- whereas Swierczewski and Raikow discuss the fined the Piciformesby their possessionof the fact that M. flexorhallucis longus also has three Type VI configurationof the deep flexor ten- heads in most passerines.Because the lateral dons,whereby M. flexorhallucis longus, which head has a different relationshipto the tendon ordinarily has a direct tendinous connection of M. iliofibularis in Passeriformes, Swier- only with the hallux (digit I), flexes digits II czewski and Raikow (1981: 473) consider that and IV as well, and M. flexordigitorum longus the "condition in the two orders is therefore flexesonly digit III. This conditionmust have probably not homologous." At this point I arisen when digit IV was reversedand began would also question whether the condition in to function as a secondhallux (zygodactyly). the Galbulae and Pici has been established as That parrotsand cuckoosare zygodactyl but do being homologous. not have the Type VI flexortendons is evidence Before I was able to consult Swierczewski's that different evolutionarypathways can pro- (1977) unpublished dissertation for details, I duce similar functional results. dissected one specimen each of the barbet The Type VI tendon arrangementwas used Trachyphonusdarnaudii (Capitonidae: Pici) and originallyto define the Piciformes,and it is still the Hypnelus bicinctus(Bucconidae: the only characterthat canbe citedto unify the Galbulae) in order to assessthe configuration order. Given that the condition of origin of M. of M. flexor hallucis in each. In the normal avi- flexor hallucis longus is part of the same com- an condition, this muscle originates in the plex and is doubtfully homologousin the Gal- popliteal fossa of the femur. In the specimen bulae and Pici anyway, then it may fairly be of Hypnelusthat I examined,the origin was said that tte new studies of osteology and January19831 PolyphyleticOrigin o[ thePici[orraes 129

A

G

D E F

Fig.2. Lateraland ventral views of skullsof a roller,Coracias benghalensis (A,D); a puffbird, panamensis(B,E); and a barbet, purpuratus (C,F). Note the greatoverall similarity between the roller() and the puffbird (Bucconidae), whereas neither dosely resembles the barbet (Capitonidae). Thearrows indicate the ventral extent of thepostorbital process, which is greatlydeveloped in the Coracii and Galbulae. Not to scale. myology of the Piciformeshave failed to reveal czewskiand Raikow(1981) amply demonstrate. a singlenew characterthat independentlycor- Of the 43 myologicalcharacters presented in roboratesthe hypothesisof monophyly. their Table1, 40% evolvedmore than oncejust If we consider that the Piciformes are not within the Piciformes.With the probability of monophyletic,then the Type VI conditionof convergencebeing so high, it is dearly im- the flexor tendons must have arisen more than practicalto justify an entire order of birds with once.This is not at all an unreasonablehy- a single myologicalcharacter. In another situ- pothesis.Convergence in myologicalcharac- ation, Bertnan and Raikow (1982: 55) found that ters occurswith great frequency, as Swier- only colies(Coliidae) and parrotshave a branch 130 STORRSL. OLSON [Auk, Vol. 100

of the M. extensordigitorum longus tendon Coracias (Coraciidae) in almost every aspect extending to the hallux; yet, they considered (Fig. 2)--bill shape, truncatepalatines, straight that "this character alone cannot demonstrate and narrow pterygoids, heavily ossifiednasal a common ancestry for the Coliiformes and septum, shape and position of the temporal Psittaciformes.... "Why, then, shoulda sin- fossae,the inflated ectethmoidplate, and the gle tendinal characterbe acceptedas demon- greatly exaggerated and ventrally produced strating the common ancestry of the Pici- post-orbital process.In all of these characters formes? the Bucconidaeare consistentlydifferent from the Pici. THE RELATIONSHIPS OF THE GALBULAE The major differencesbetween the skulls of AND THE ]VICI the Bucconidae and Coracias are in the reduced Here, I will briefly outline my reasons for lacrimal and the dorsal expansion of the pala- believing the Galbulaeto be closelyrelated to tines onto the parasphenoid rostrum in the the rollers, or Coracii of Maurer and Rai- Bucconidae. These differences are more like kow (1981), which includes the Coraciidae, thoseobserved between genera within a Brachypteraciidae,and Leptosomidae.The Pici, than between different orders. They are less on the other hand, I believe are more closely profound than the differences observed be- related to the Passeriformes. These observa- tween the four families of Pici, for example. In tions are preliminary; a more completeassess- many respects,the skull of Coraciasdiffers less ment of the interrelationshipsof all the higher from that of the bucconidMalacoptila than it orders of land birds requires more evidence does from Eurystomus,the only other modern than is now available. For example, it is diffi- in the Coraciidae. cult to make myological comparisonsof the In the Galbulae, and in all of the Coracii, the Piciformesand Coraciiformesfrom the existing postorbitalprocess is greatlyenlarged and ex- literature because Swierczewski and Raikow tends straight ventrally as far as the jugal bar (1981)and Maurer and Raikow (1981)have pre- (Fig. 2). From this there is a very strong,short, sented only the evidence that supports their post-orbital ligament that attachesto a process classifications,while omitting the descriptive on the medial surfaceof the mandible just an- observations of actual dissections. Even with terior to the articulation (Fig. 3). The M. ad- access to the unpublished dissertations of ductor mandibulae complexis correspondingly Swierczewski (3.977) and Maurer (1977), cross narrowed, enabling it to passthrough the rel- comparisons are difficult, because a character atively small foramen formed by the enlarged that was deemed important in one group was postorbitalprocess (Fig. 3). On the other hand, often not consideredsignificant in the other, the postorbitalprocess is quite smallin the Pici, so that certaindescriptions may be inadequate most Passeriformes,the Trogonidae,and in the for comparison,necessitating the re-examina- remainder of the Coraciiformesexcept the Bu- tion of specimens. cerotidae and some of the Momotidae. In the Sibley and Ahlquist (1972) have previously last two instances, the postorbital process is suggesteda relationshipbetween the Galbulae well developedbut does not extend nearly as and the , but they particularly far ventrally as it does in the Coracii and the singled out the kingfishers (Alcedinidae) as Galbulae. In the one example of barbet possibleaffines. The kingfishers,however, be- (Trachyphonusdarnaudii) that I dissected, the long to the alcedinine group of Coraciiformes postorbitalligament was very weak and was that is characterizedby a derived morphology scarcelydifferentiated from the overlying fas- of the stapes (Feduccia 1975) and several de- ciae. rived myological characters(Maurer and Rai- In the elementsof the postcranialskeleton of kow 1981) that do not occur in the Galbulae. A the Galbulae, there is greater similarity to the lack of relationship between the Galbulae and Coracii than to the Pici. The coracoid in the the Alcedinidae does not, however, precludea Galbulae is almost identical to that in the roller relationship between the Galbulae and some group (Fig. 4) and is very different from that other section of the Coraciiformes. found in the Pici. The humeri and carpometa- The skull and mandible in the Galbulae, par- carpi in the Galbulae are also more similar to ticularly in the less-specializedfamily Buccon- those in the rollers than to the Pici (see below). idae, show a remarkable similarity to those of Those who have experience identifying lanuary1983] PolyphyleticOrigin of thePiciformes 131

pometacarpus in the Pici differs from that in m the Galbulaeand Coraciiformesin havinga broad and very well-developedintermetacar- pal tubercle,a conditionshared only with the Passedfformesamong the higher land birds. The humerus in the Pici differs from that in the Galbulae and Coraciiformes and resembles that in the Passedfformesin having the shaftshort and stout, the proximal end broader, and the deltoidcrest squared, rather than triangular or m rounded. Whereas we have seen that no characters in- dependentof the deep flexortendons could be foundto corroboratepiciform monophyly, most B othercharacters, whatever their "polarity" may be, are concordant when the Galbulae are al- lied with the Coracii and the Pici are allied P with the Passeriformes.Thus, the oil glandis covered with down and lacks a tufted orifice in the Galbulae and Coracii but is nude, with a tufted orifice, in the Pici and Passedfformes (Gadow1896). The caecaare well developed in G the Gabulae and Coracii but absent or rudi- mentary in the Pici and Passedformes(Gadow Fig. 3. Dissectedheads of a roller,Coracias gar- 1896; pers. obs. for Galbulae). The structure of rulus(A); a puffbird, pectoralis (B); and a the down in the Galbulae is like that of the barbet,Trachyphonus darnaudii (C). Note the marked Coracii, whereas that of the Pici is similar to similaritybetween the rollerand the puffbird in the that of the Passedfformes(Chandler 1916). Of verystrong ligament (1) from the enlarged postorbital process to the mandible and in the narrowed adduc- the six derived myologicalcharacters that tor mandibulaecomplex (m), whereasin the barbet Swierczewskiand Raikowuse to definethe Pici, thepostorbital process (p) is very small, the ligament four (characters1, 33, 39, and 41) are found in is vestigial,and the adductor mandibulae complex is most, some, or all passedfies.Mm. popliteus, of morenormal development. Not to scale. adductordigiti II, andextensor brevis digiti IV are absent in the Pici (characters33, 39, and 41) and in Passeriformes,whereas eachof these musclesis presentin both the Galbulae and the isolated bones are aware of the skeletal Coracii.If my interpretationof Maurer's(1977) similarities between the Pici and the Passeri- descriptionsis correct,four characters(15, 29, formes;a possiblerelationship between these 31, and 32) of the six that Swierczewski and two groupshas long beenrecognized (see Sib- Raikow (1981) use to define the Galbulae as ley and Ahlquist1972). Lowe (1946) considered monophyleticalso occur in the Coracii, where- the Pici to be but a suborder of the Passedf- as only two (14 and 42) appearto be unique formes and did not include or even mention (autapomorphous).When all of the data can be the Galbulae. analyzed, I am confident that there will be far The coracoif in the Pici and Passeriformes is fewer character conflicts when the Piciformes very slenderand elongate,with the sternalend are split apart, as I have proposedhere, than andhead narrow, the sterno-coracoidal process whenthey are maintained as monophyletic. reduced,and the procoracoidprocess usually vestigialor evenabsent (Fig. 4). This contrasts with the condition in the Galbulae and most COMMENTS ON FOSSIL TAXA Coraciiformes, in which the coracoif is com- paratively short, the head and sternal end Simpson and Cracra[t's (1981: 491) discus- expanded,and the sterno-coracoidaland pro- sionso[ the Primobucconidaeand Zygodacty- coracoif processeswell developed.The car- lidae are misleading.Their statementthat the 132 STORRSL. OLSON [Auk,Vol. 100

A B C D

Fig. 4. Ventral view of coracoidsto show the similarities between the ground roller Brachypteracias leptosornus(A), and a puffbird, Malacoptilapanarnensis (B). Thesediffer greatlyfrom the coracoidin the Pici (C, the , auratus), which is morelike that in passerines(D, a rhinocryptid,Pteroptochos rnegapodius).Not to scale.

Primobucconidae have not been shown to be tors that were not zygodactyl, and forms tran- a monophyletic group is irrelevant. Such a sitional between those ancestorsand the fully statement could truthfully be made about the zygodactyl modem Galbulae must have exist- vast majority of groups of birds or other or- ed. The Galbulae would have to be included at ganisms. Simpson and Cracraft present no in- some taxonomic level with birds that did not formation to suggestthat the primobucconids have the fourth trochlea as modified as do the are not monophyletic. Their contention that modem members of the suborder. Because "the bucconidsand galbulids are fully zygo- Simpson and Cracraft present no evidence to dactyl," but that the " genera [of pri- showthat the primobucconidsare moreclosely mobucconids]are not," hinges entirely on the related to some other group, there is no reason definition of "fully zygodactyl,"which they do not to follow Brodkorb (1970) and Feduccia and not provide. Two specimens of primobuccon- Martin (1976)in consideringthe Primobuccon- ids (the holotype of Neanis kistneri, Feduccia idae to be primitive members of the Galbulae 1973; and the holotype of Primobuccoolsoni, that share more similarities with the Bucconi- Feduccia and Martin 1976) are preserved with dae than with any otherextant family of birds. the outer toe completelyreversed, in the zygo- Simpsonand Cracraft(1981: 492) tentatively dactyl manner. Perhaps by "fully zygodactyl" suggest"placing the Zygodactylidaeas a Simpson and Cracraftmean that the primobuc- member of the Pici," but they presentno evi- conids do not have the fourth trochlea and seh- dence for this either. Ballmann (1969a, b) de- henhalter as modified as in other zygodactyl liberately did not put Zygodactylusin any ex- birds, but the primobucconidswere certainly isting order, because he considered that its functionallyzygodactyl. [Note also that Simp- affinities could not be determined from the tar- son and Cracraft (1981:491) misquote Feduccia sometatarsusand tibiotarsus, the only ele- and Martin (1976)--the description of the pri- ments yet known. For descriptivepurposes he mobucconid tarsometatarsus should read "a made comparisons not only with the Pici- distinct grooveseparating the posteriorportion formes but also with the Psittaciformes. Ball- of the trochlea" not "supporting" it.] mann (pers. comm.) has emphasizedverbally Simpson and Cracraft contendthat the more to me his belief that Zygodactylusis not pici- primitive tarsal morphology of the primobuc- form. If Zygodactylustells us anythingat this conids arguesagainst their being placed with- point, it is probably that the specializedzygo- in the Galbulae, but this follows only if one dactyl condition of the tarsometatarsus, in defines the Galbulae solely by the possession which the fourth trochleabecomes enlarged and of a completely modified fourth trochlea. At bears a sehnenhalter,has evolved yet another somepoint, the Galbulae obviouslyhad ances- time. January1983] PolyphyleticOrigin of the Piciformes 133

CONCLUSION CHANDLER,A. C. 1916. A study of the structureof , with reference to their taxonomic sig- As I have indicated elsewhere (Olson 1981), nificance. Univ. California Publ. Zool. 13: 243- the higher level systematicsof birds has a very 446. poor foundation. The questionsof whether or FEDUCCIA,A. 1973. A new Eocenezygodactyl bird. not currently recognizedorders are monophy- J. Paleontol. 47: 501-503. letic and what the interrelationshipsof these 1975. Morphologyof the bony stapes(col- ordersmay be are still largelyunanswered. Al- umella) in the Passeriformesand related groups: though the studies of Swierczewski and Rai- evolutionary implications. Univ. Kansas Mus. Nat. Hist. Misc. Publ. 3: 1-34. kow (1981) and Maurer and Raikow (1981) are , • L. D. MARTIN. 1976. The Eocene zygo- useful in documentingthe monophylyof some dactyl birds of North America (Aves: Pici- of the subunits of Coraciiformes and Pici- formes). Smithsonian Contr. Zool. 27: 101-110. formes, at the level of ordinal and interordinal GADOW,H. 1893. Vogel. II. SystematischerTheil. systematicsthey are less successful.Despite Pp. 259-270in Klassenund Ordnungendes Thier- these workers' accumulation of much new data, Reichs, vol. 6(4) (H. G. Bronn, Ed.). Leipzig, C. they could recognizethe ordersPiciformes and F. Winter. Coraciiformes as monophyletic only by the ß 1896. Caeca, pp. 68-70; Oil-gland, pp. 653- configuration of the deep flexor tendons--the 654 in A dictionary of birds (A. Newton). Lon- same character that had been used to define don, Adam & Charles Black. these orders nine decades ago. Their studies LowE, P. R. 1946. On the systematicposition of the (Pici), honey-guides (Indica- were designed only so as to test hypotheses tor), hoopoes, and others. Ibis 88: 103-127. that had previouslybeen formulated,whereas MAURER,D. g. 1977. The appendicularmyology they seem to lack the means to generate alter- and relationships of the avian order Coracii- native hypotheses.Herewith, I have supplied formes. Unpublished Ph.D. dissertation, Pitts- one for the Piciformes, and there is every rea- burgh, Pennsylvania,Univ. Pittsburgh. son to expect alternative hypotheses of rela- , & g. J. RAIKOW. 1981. Appendicular myol- tionships for the Coraciiformesand for other ogy, phylogeny, and classificationof the avian orders based on single charactersor that are order Coraciiformes(including Trogoniformes). otherwisepoorly defined. Ann. Carnegie Mus. Nat. Hist. 50: 417-434. OriSON, S. L. 1981. The museum tradition in or-

ACKNOWLEDGMENTS nithology--a responseto Ricklefs.Auk 98: 193- 195. I am grateful to Helen F. James,David W. Stead- ß 1982. A critique of Cracraft's classification man, Richard P. Vari, and Richard L. Zusi for read- of birds. Auk 99: 733-739. ing and commenting on the manuscript. I am like- SIBLEY,C. G., & J. A. AHLQUIST. 1972. A compar- wise indebted to Victor E. Krantz for the photog- ative study of the -white proteins of non- raphy. passerinebirds. Peabody Mus. Nat. Hist. Yale Univ. Bullß 39: 1-276. LITERATURE CITED SIMPSON,S. F., & J. CRACRAFT.1981. The phylo- genetic relationships of the Piciformes ( BALLMANN, P. 1969a. Les oiseaux mioc•nes de La Aves). Auk 98: 481-494. Grive-Saint-Alban (Is•re). Geobios 2: 157-204. STEINBACHER, Gß 1935. Funktionell-anatomische 1969b. Die V6gel aus der altburdigalen Untersuchungenan Vogelffissenmit Wendezeh- SpaltenffJllungvon Wintershof (West) bei Eich- en und Rfickzehen. J. Ornithol. 83: 214-282. st•tt in B'ayern.Zitteliana 1: 5-60. SWIERCZEWSKI,E.V. 1977ß The hindlimb myology BERMAI•,S. L., & g. J. RAIKOW. 1982. The hindlimb and phylogeneticrelationships of the avian or- musculature of the (Coliiformes). Auk 99: 41-57. der Piciformes. Unpublished Ph.D. dissertation, BOCK, W., & W. DEW. MILLER. 1959. The scan- Pittsburgh,Pennsylvania, Univ. Pittsburgh. , & g. J. RAIKOW. 1981. Hind limb mor- soffal foot of the woodpeckers, with comments phology,phylogeny, and classificationof the Pi- on the of perchingand climbing feet ciformes. Auk 98: 466-480. in birds. Amer. Mus. Novitates 1931: 1-45. BRODKORB,P. 1970. An Eocenepuffbird from Wy- oming. Univ. Wyoming Contr. Geol. 9: 13-15.